WikiVet English - User contributions [en]

Colic Diagnosis - General Physical Examination

2013-03-05T22:06:39Z

Ge8680: /* Cardiovascular Parameters */

{{review}}

===General Physical Examination===
[[File:Gingival Mucous Membranes.jpg|thumb|200px|right| Picture of a horse's mouth demonstrating cyanotic gingival mucosa(Courtesy of Potter K, SPANA)]]
A physical examination including the following parameters should be carried out immediately and thoroughly.
* Attitude and External appearance
* Abdominal contour (distention-unilateral vs. bilateral)
* Body Temperature
* Heart Rate and Pulse character, Respiratory rate and effort
* Skin Turgor, Mucous membrane color and moisture, Capillary refil time (CRT)
* Presence of digital pulses

For normal physiology values in horses, click [[Equine Section - WikiNormals|here]].

=====Attitude and External Appearance=====
It is important to assess the degree of pain. It is best do keep the patient in a quiet environment to fully assess them. If the owner or trainer of the horse has administered any treatments then the patients status may not be a true reflection of the clinical condition. If the horse is in severe, unrelenting pain and it is difficult to assess it safely, it is advisable to administer some analgesics, sedation and butyl-scopolamine prior to the examination. It is useful to get the heart rate prior to the administration of these medications due to their transient effects on the resting heart rate.

A horse with severe pain that is unresponsive to analgesics warrants going to surgery as soon as possible if it is a case of a strangulating obstruction. Multiple abrasions around the head and periorbital area indicate that the horse is experiencing severe pain. The duration of clinical signs is important to note as once the strangulated portion of intestine degenerates to a certain point, the pain will subside but the horse becomes increasingly depressed.

Non-infarctive conditions such as impactions and some ileal intussusceptions are demonstrated as intermittently, moderately painful cases.

A depressed horse that is pyrexic and displaying signs of moderate abdominal pain may indicate an inflammatory condition such as an enteritis, colitis of peritonitis.

The examination should also include the mouth for the presence of malocclusion, dental abnormalities, damage to the lips and gums, nasal discharge and excessive salivation. The abdominal contour should be examined for any swellings or recent enlargements which could indicate edema or umbilical, abdominal or scrotal herniations.
[[File:Collapsed horse.jpg|thumb|300px|center| Picture of a collapsed horse with periorbital abrasions and sweating up(Courtesy of Potter K, SPANA)]]

=====Abdominal Distension=====
Any degree of abdominal distension is usually indicative of a condition affecting the large intestines, as distension of the stomach and small intestine would not be large enough to be visible externally.

=====Body Temperature=====
Pyrexia may indicate an inflammatory or infectious condition and should be interpreted with other diagnostic tests such as fecal samples, hematology, biochemistry and blood cultures.

=====Cardiovascular Parameters=====
Tachypnoea and tachychardia can be seen in the horse with colic. This is due to pain, but mainly due to decreased circulating volume, decreased preload, and endotoxemia. The pulse can be palpated in the facial, digital, brachial and great metatarsal arteries. The heart rate should be measured over time, and its response to analgesic therapy ascertained. The pulse should be assessed at different sites. The blood pressure can be assessed with the use of a blood pressure cuff and Doppler around the coccygeal artery. The normal systolic pressure of a an adult horse should be 100 to 125 mm Hg. Horses with colic that have a systolic pressure of less than 80 mm Hg had a poorer prognosis. A pulse that continues to rise in rate to 60 to 70 beats per minute and weaken in quality over 6 to 8 hours in the face of adequate analgesia is considered a surgical indication. Infarctive disease is characterised by an increasing, non-fluctuating heart rate.

Mucous membrane colour and moisture and capillary refil time (CRT) can be assessed to appreciate the severity of haemodynamic compromise. The normal colour is pale pink and the CRT is 1 to 2 seconds. The gingival mucous membranes change from pink and moist to red and dry as the circulating blood volume decreases. The genital and conjunctival mucosa can also be assessed. Reddening of the mucous membranes indicates haemoconcentration and worsens as the patient goes into shock. Reddening reflects worse prognosis, and cyanotic membranes indicate a very poor chance of a positive outcome as it it indicates that the horse is in endotoxic shock. The CRT will be prolonged with dehydration and endotoxaemia.
[[File:Ocular Mucous Membrane.jpg|thumb|200px|center| Picture of a horse's eye with congested conjunctical mucosa(Courtesy of Potter K, SPANA)]]

The skin over the neck or eyelid can be tented to crudely assess the hydration status of the horse. The skin of a normally hydrated horse should return to its initail position almost immediately. A reduced skin tent indicates dehydration.
[[File:Skin Tent.jpg|thumb|200px|center| Picture of a dehydrated horse with a reduced skin tent underneath the intravenous jugular catheter(Courtesy of Potter K, SPANA)]]

===References===
* Edwards B. (2009), Diagnosis and Pathophysiology of Intestinal Obstruction, in Equine Gastroenterology courtesy of the University of Liverpool, pp 7-9
* Meuller E, Moore J. N, (2008) Classification and Pathophysiology of Colic, Gastrointestinal Emergencies and Other Causes of Colic, in Equine Emergencies- Treatments and Procedures, 3rd Edition, Eds Orsini J. A, Divers T.J, Saunders Elsevier, pp 107-109
* Rose R.J, Hodgson D.R (2000) Examination of the Alimentary Tract, Alimentary Tract, Manual of Equine Practice, 2nd Edition, Saunders Elsevier, pp 293

[[Category:Colic_Diagnosis_in_the_Horse|C]]

Colic Diagnosis - General Physical Examination

2013-03-05T22:05:21Z

Ge8680: /* Cardiovascular Parameters */

{{review}}

===General Physical Examination===
[[File:Gingival Mucous Membranes.jpg|thumb|200px|right| Picture of a horse's mouth demonstrating cyanotic gingival mucosa(Courtesy of Potter K, SPANA)]]
A physical examination including the following parameters should be carried out immediately and thoroughly.
* Attitude and External appearance
* Abdominal contour (distention-unilateral vs. bilateral)
* Body Temperature
* Heart Rate and Pulse character, Respiratory rate and effort
* Skin Turgor, Mucous membrane color and moisture, Capillary refil time (CRT)
* Presence of digital pulses

For normal physiology values in horses, click [[Equine Section - WikiNormals|here]].

=====Attitude and External Appearance=====
It is important to assess the degree of pain. It is best do keep the patient in a quiet environment to fully assess them. If the owner or trainer of the horse has administered any treatments then the patients status may not be a true reflection of the clinical condition. If the horse is in severe, unrelenting pain and it is difficult to assess it safely, it is advisable to administer some analgesics, sedation and butyl-scopolamine prior to the examination. It is useful to get the heart rate prior to the administration of these medications due to their transient effects on the resting heart rate.

A horse with severe pain that is unresponsive to analgesics warrants going to surgery as soon as possible if it is a case of a strangulating obstruction. Multiple abrasions around the head and periorbital area indicate that the horse is experiencing severe pain. The duration of clinical signs is important to note as once the strangulated portion of intestine degenerates to a certain point, the pain will subside but the horse becomes increasingly depressed.

Non-infarctive conditions such as impactions and some ileal intussusceptions are demonstrated as intermittently, moderately painful cases.

A depressed horse that is pyrexic and displaying signs of moderate abdominal pain may indicate an inflammatory condition such as an enteritis, colitis of peritonitis.

The examination should also include the mouth for the presence of malocclusion, dental abnormalities, damage to the lips and gums, nasal discharge and excessive salivation. The abdominal contour should be examined for any swellings or recent enlargements which could indicate edema or umbilical, abdominal or scrotal herniations.
[[File:Collapsed horse.jpg|thumb|300px|center| Picture of a collapsed horse with periorbital abrasions and sweating up(Courtesy of Potter K, SPANA)]]

=====Abdominal Distension=====
Any degree of abdominal distension is usually indicative of a condition affecting the large intestines, as distension of the stomach and small intestine would not be large enough to be visible externally.

=====Body Temperature=====
Pyrexia may indicate an inflammatory or infectious condition and should be interpreted with other diagnostic tests such as fecal samples, hematology, biochemistry and blood cultures.

=====Cardiovascular Parameters=====
Tachypnoea and tachychardia can be seen in the horse with colic. This is due to pain, but mainly due to decreased circulating volume, decreased preload, and endotoxemia. The pulse can be palpated in the facial, digital, brachial and great metatarsal arteries. The heart rate should be measured over time, and its response to analgesic therapy ascertained. The pulse should be assessed at different sites. The blood pressure can be assessed with the use of a blood pressure cuff and Doppler around the coccygeal artery. The normal systolic pressure of a an adult horse should be 100 to 125 mm Hg. Horses with colic that have a systolic pressure of less than 80 mm Hg had a poorer prognosis. A pulse that continues to rise in rate to 60 to 70 beats per minute and weaken in quality over 6 to 8 hours in the face of adequate analgesia is considered a surgical indication. Infarctive disease is characterised by an increaseing, non-fluctuating heart rate.

Mucous membrane colour and moisture and capillary refil time (CRT) can be assessed to appreciate the severity of haemodynamic compromise. The normal colour is pale pink and the CRT is 1 to 2 seconds. The gingival mucous membranes change from pink and moist to red and dry as the circulating blood volume decreases. The genital and conjunctival mucosa can also be assessed. Reddening of the mucous membranes indicates haemoconcentration and worsens as the patient goes into shock. Reddening reflects worse prognosis, and cyanotic membranes indicate a very poor chance of a positive outcome as it it indicates that the horse is in endotoxic shock. The CRT will be prolonged with dehydration and endotoxaemia.
[[File:Ocular Mucous Membrane.jpg|thumb|200px|center| Picture of a horse's eye with congested conjunctical mucosa(Courtesy of Potter K, SPANA)]]

The skin over the neck or eyelid can be tented to crudely assess the hydration status of the horse. The skin of a normally hydrated horse should return to its initail position almost immediately. A reduced skin tent indicates dehydration.
[[File:Skin Tent.jpg|thumb|200px|center| Picture of a dehydrated horse with a reduced skin tent underneath the intravenous jugular catheter(Courtesy of Potter K, SPANA)]]

===References===
* Edwards B. (2009), Diagnosis and Pathophysiology of Intestinal Obstruction, in Equine Gastroenterology courtesy of the University of Liverpool, pp 7-9
* Meuller E, Moore J. N, (2008) Classification and Pathophysiology of Colic, Gastrointestinal Emergencies and Other Causes of Colic, in Equine Emergencies- Treatments and Procedures, 3rd Edition, Eds Orsini J. A, Divers T.J, Saunders Elsevier, pp 107-109
* Rose R.J, Hodgson D.R (2000) Examination of the Alimentary Tract, Alimentary Tract, Manual of Equine Practice, 2nd Edition, Saunders Elsevier, pp 293

[[Category:Colic_Diagnosis_in_the_Horse|C]]

Cephalosporins

2012-10-07T21:39:30Z

Ge8680: /* Spectrum of Activity */

{{review}}
{{toplink
|linkpage =WikiDrugs
|linktext =WikiDrugs
|sublink1 = Antibiotics
|subtext1 = Antibiotics
|pagetype = Drugs
}}

[[Image: Cephalosporin.png|thumb|right|250px|The Core Structure of Cephalosporins]]

==Mechanism of Action==

Cephalosporins are '''beta-lactams''' just like [[penicillins]] and work by disrupting the peptidoglycan in the cell wall of bacteria. As such they are '''bacteriocidal''' and time dependent killers.

==Spectrum of Activity==

Unlike penicillins it is hard to make broad generalisations about the spectrum of activity of the cephalosporin sub-groups. The two common points are that they are all stable to Staphylcococal beta lactamase and are effective against most obligate anaerobes.

'''First Generation Cephalosporins''' - Cefalexin, Cefalonium, Cephapirin
* Active against gram positive organisms
* Active aginst many gram negatives. ''Pseudomonas'' species are resistant.

'''Second Generation Cephalosporins''' - Cefuroxime
* Very broad spectrum with very high activity against enterobacteriaeceae.
* Struggle against the most difficult gram negative organisms

'''Third Generation Cephalosporins''' - Cefoperazone, Ceftiofur
* Very active against gram negatives, especially the hardier species, including ''Pseudomonas''
* Less active against gram positives compared to other cephalosporins; Staphylococci and enterococci can be resistant.

'''Fourth Generation Cephalosporins''' - Cefquinome
* Very broad spectrum, only the very hardiest of gram negatives aren't susceptible. It is still active againts ''Pseudomonas''.

==Pharmacokinetic Considerations==

They are organic acids, hydrophilic and will ionise at physiological pH. They generally have poor oral bioavailability as they unstable in acid environments. They have a limited volume of distribution (0.2-0.3l/kg), this means the drug is mainly confined to plasma and interstitial space. As the are hydrophilic they can't enter cells and won't cross the blood brain barrier, unless it is damaged. They have short half-lives of about 0.5 - 1.2 hours. They are readily excreted by the kidneys, via tubular secretion in the proximal convoluted tubule. This results in high concentrations of the drug in urine.

Exceptions are:

* Cefalexin which is stable in acid and so suitable for oral dosing.
* Ceforperazone is excreted in bile rather than in urine.

==Side Effects and Contraindications==

* Like Penicillins they can cause '''fatal colitis''' in hamsters and guinea-pigs.
* They are often painful when given intramuscularly.
* Very high doses has been known to result in nephrotoxicity.
* They can result in bleeding problems because of interference with the formation of vitamin K in the gut (esp Moxalactam).

Small Ruminants Breeds - WikiNormals

2011-07-30T15:36:42Z

Ge8680:

<imagemap>
Image:Ovine Normals Breeds.jpg|200px|Small Ruminants Breeds
rect 0 0 650 301 [[Small Ruminants Breeds - WikiNormals]]
desc none
</imagemap>

{{toplink
|linkpage =WikiNormals
|linktext =WikiNormals

|pagetype =WikiNormals
|sublink1= Small Ruminants Section - WikiNormals
|subtext1= Small Ruminants Section
}}
==Ovine==
<gallery widths="115px" perrow="5">
File:Badgerface ewe, Wales.jpg|'''Badger Face Welsh Mountain'''
Image:ImageNeeded.png|'''Balwen Welsh Mountain'''
Image:ImageNeeded.png|'''Beltex'''
Image:ImageNeeded.png|'''Berrichon Du Cher'''
Image:ImageNeeded.png|'''Beulah Speckled Face'''
Image:ImageNeeded.png|'''Blackface'''
Image:ImageNeeded.png|'''Black Welsh Mountain'''
File:Bleu du Maine in Flanders.jpg|'''Bleu Du Maine'''
Image:ImageNeeded.png|'''Bluefaced Leicester'''
File:LeicesterFronteiriza.jpg|'''Border Leicester'''
Image:ImageNeeded.png|'''Boreray'''
Image:ImageNeeded.png|'''Brecknock Hill Cheviot'''
Image:ImageNeeded.png|'''British Inra 401'''
Image:ImageNeeded.png|'''British Milksheep'''
Image:ImageNeeded.png|'''Cambridge'''
File:Borris the ram shorn.jpg|'''Castlemilk Moorit'''
Image:ImageNeeded.png|'''Charmoise Hill'''
Image:ImageNeeded.png|'''Charollais'''
File:Shearling Cheviot ram.jpg|'''Cheviot'''
Image:ImageNeeded.png|'''Clun Forest'''
Image:ImageNeeded.png|'''Colbred'''
Image:ImageNeeded.png|'''Cotentin'''
Image:ImageNeeded.png|'''Cotswold'''
Image:ImageNeeded.png|'''Dalesbred'''
File:Anybody know a good barber?.jpg|'''Dartmoor (Greyface)'''
Image:ImageNeeded.png|'''Derbyshire Gritstone'''
Image:ImageNeeded.png|'''Devon Closewool'''
Image:ImageNeeded.png|'''Devon And Cornwall Longwool'''
Image:ImageNeeded.png|'''Dorset Down'''
Image:ImageNeeded.png|'''Dorset Horn & Poll Dorset'''
Image:ImageNeeded.png|'''Est A Laine Merino'''
Image:ImageNeeded.png|'''Exmoor Horn'''
Image:ImageNeeded.png|'''Friesland'''
Image:ImageNeeded.png|'''Gotland'''
Image:ImageNeeded.png|'''Hampshire Down'''
File:Hebridean Sheep - Waters' Edge Country Park - geograph.org.uk - 1442307.jpg|'''Hebridean'''
File:Herdwick ewe1.jpg|'''Herdwick'''
Image:ImageNeeded.png|'''Hill Radnor'''
Image:ImageNeeded.png|'''Icelandic'''
Image:ImageNeeded.png|'''Ile De France'''
File:Jacob Ram at Royal Show.jpg|'''Jacob'''
Image:ImageNeeded.png|'''Kerry Hill'''
Image:ImageNeeded.png|'''Leicester Longwool'''
Image:ImageNeeded.png|'''Lincoln Longwool'''
Image:ImageNeeded.png|'''Llanwenog'''
Image:ImageNeeded.png|'''Lleyn'''
Image:ImageNeeded.png|'''Lonk'''
Image:ImageNeeded.png|'''Manx Loaghtan'''
Image:ImageNeeded.png|'''Masham'''
Image:ImageNeeded.png|'''Meatlinc'''
File:Norfolk Horn wether.jpg|'''Norfolk Horn'''
Image:ImageNeeded.png|'''North Country Cheviot'''
Image:ImageNeeded.png|'''North Ronaldsay'''
Image:ImageNeeded.png|'''Oxford Down'''
Image:ImageNeeded.png|'''Portland'''
Image:ImageNeeded.png|'''Romney'''
Image:ImageNeeded.png|'''Rouge De L'ouest'''
Image:ImageNeeded.png|'''Rough Fell'''
Image:ImageNeeded.png|'''Roussin'''
Image:ImageNeeded.png|'''Ryeland'''
Image:ImageNeeded.png|'''Scotch Halfbred'''
Image:ImageNeeded.png|'''Scottish Greyface'''
Image:ImageNeeded.png|'''Shetland'''
Image:ImageNeeded.png|'''Shetland-Cheviot'''
Image:ImageNeeded.png|'''Shropshire'''
Image:ImageNeeded.png|'''Soay'''
Image:ImageNeeded.png|'''Southdown'''
Image:ImageNeeded.png|'''South Wales Mountain'''
File:7 month old Suffolk Ram Lamb.JPG|'''Suffolk'''
File:Ranelands Farm, Swaledale.jpg|'''Swaledale'''
Image:ImageNeeded.png|'''Teeswater'''
File:Texel sheep.jpg|'''Texel'''
Image:ImageNeeded.png|'''Vendeen'''
Image:ImageNeeded.png|'''Welsh Hill Speckled Face'''
Image:ImageNeeded.png|'''Welsh Mountain'''
Image:ImageNeeded.png|'''Wensleydale'''
Image:ImageNeeded.png|'''White Face Dartmoor'''
Image:ImageNeeded.png|'''White Faced Woodland'''
Image:ImageNeeded.png|'''Wiltshire Horn'''
Image:ImageNeeded.png|'''Zwartbles'''
<--Add more breeds here-->

</gallery>
==Capra Hircus==
<gallery widths="115px" perrow="5">
Image:ImageNeeded.png|'''Anglo-Nubian'''
Image:ImageNeeded.png|'''Angora'''
Image:ImageNeeded.png|'''Bagot'''
Image:ImageNeeded.png|'''Boer'''
Image:ImageNeeded.png|'''British Alpine'''
Image:ImageNeeded.png|'''British Saanen'''
Image:ImageNeeded.png|'''British Toggenburg'''
Image:ImageNeeded.png|'''Cashmere'''
Image:ImageNeeded.png|'''Saanen'''
Image:ImageNeeded.png|'''Toggenburg'''
<--Add more breeds here-->

</gallery>

[[Category:Lost]]

Small Ruminants Breeds - WikiNormals

2011-07-30T12:47:38Z

Ge8680:

<imagemap>
Image:Ovine Normals Breeds.jpg|200px|Small Ruminants Breeds
rect 0 0 650 301 [[Small Ruminants Breeds - WikiNormals]]
desc none
</imagemap>

{{toplink
|linkpage =WikiNormals
|linktext =WikiNormals

|pagetype =WikiNormals
|sublink1= Small Ruminants Section - WikiNormals
|subtext1= Small Ruminants Section
}}
==Ovine==
<gallery widths="115px" perrow="5">
Image:ImageNeeded.png|'''Badger Face Welsh Mountain'''
Image:ImageNeeded.png|'''Balwen Welsh Mountain'''
Image:ImageNeeded.png|'''Beltex'''
Image:ImageNeeded.png|'''Berrichon Du Cher'''
Image:ImageNeeded.png|'''Beulah Speckled Face'''
Image:ImageNeeded.png|'''Blackface'''
Image:ImageNeeded.png|'''Black Welsh Mountain'''
Image:ImageNeeded.png|'''Bleu Du Maine'''
Image:ImageNeeded.png|'''Bluefaced Leicester'''
Image:ImageNeeded.png|'''Border Leicester'''
Image:ImageNeeded.png|'''Boreray'''
Image:ImageNeeded.png|'''Brecknock Hill Cheviot'''
Image:ImageNeeded.png|'''British Inra 401'''
Image:ImageNeeded.png|'''British Milksheep'''
Image:ImageNeeded.png|'''Cambridge'''
Image:ImageNeeded.png|'''Castlemilk Moorit'''
Image:ImageNeeded.png|'''Charmoise Hill'''
Image:ImageNeeded.png|'''Charollais'''
Image:ImageNeeded.png|'''Cheviot'''
Image:ImageNeeded.png|'''Clun Forest'''
Image:ImageNeeded.png|'''Colbred'''
Image:ImageNeeded.png|'''Cotentin'''
Image:ImageNeeded.png|'''Cotswold'''
Image:ImageNeeded.png|'''Dalesbred'''
Image:ImageNeeded.png|'''Dartmoor (Greyface)'''
Image:ImageNeeded.png|'''Derbyshire Gritstone'''
Image:ImageNeeded.png|'''Devon Closewool'''
Image:ImageNeeded.png|'''Devon And Cornwall Longwool'''
Image:ImageNeeded.png|'''Dorset Down'''
Image:ImageNeeded.png|'''Dorset Horn & Poll Dorset'''
Image:ImageNeeded.png|'''Est A Laine Merino'''
Image:ImageNeeded.png|'''Exmoor Horn'''
Image:ImageNeeded.png|'''Friesland'''
Image:ImageNeeded.png|'''Gotland'''
Image:ImageNeeded.png|'''Hampshire Down'''
Image:ImageNeeded.png|'''Hebridean'''
Image:ImageNeeded.png|'''Herdwick'''
Image:ImageNeeded.png|'''Hill Radnor'''
Image:ImageNeeded.png|'''Icelandic'''
Image:ImageNeeded.png|'''Ile De France'''
Image:ImageNeeded.png|'''Jacob'''
Image:ImageNeeded.png|'''Kerry Hill'''
Image:ImageNeeded.png|'''Leicester Longwool'''
Image:ImageNeeded.png|'''Lincoln Longwool'''
Image:ImageNeeded.png|'''Llanwenog'''
Image:ImageNeeded.png|'''Lleyn'''
Image:ImageNeeded.png|'''Lonk'''
Image:ImageNeeded.png|'''Manx Loaghtan'''
Image:ImageNeeded.png|'''Masham'''
Image:ImageNeeded.png|'''Meatlinc'''
Image:ImageNeeded.png|'''Norfolk Horn'''
Image:ImageNeeded.png|'''North Country Cheviot'''
Image:ImageNeeded.png|'''North Ronaldsay'''
Image:ImageNeeded.png|'''Oxford Down'''
Image:ImageNeeded.png|'''Portland'''
Image:ImageNeeded.png|'''Romney'''
Image:ImageNeeded.png|'''Rouge De L'ouest'''
Image:ImageNeeded.png|'''Rough Fell'''
Image:ImageNeeded.png|'''Roussin'''
Image:ImageNeeded.png|'''Ryeland'''
Image:ImageNeeded.png|'''Scotch Halfbred'''
Image:ImageNeeded.png|'''Scottish Greyface'''
Image:ImageNeeded.png|'''Shetland'''
Image:ImageNeeded.png|'''Shetland-Cheviot'''
Image:ImageNeeded.png|'''Shropshire'''
Image:ImageNeeded.png|'''Soay'''
Image:ImageNeeded.png|'''Southdown'''
Image:ImageNeeded.png|'''South Wales Mountain'''
Image:ImageNeeded.png|'''Suffolk'''
Image:ImageNeeded.png|'''Swaledale'''
Image:ImageNeeded.png|'''Teeswater'''
Image:ImageNeeded.png|'''Texel'''
Image:ImageNeeded.png|'''Vendeen'''
Image:ImageNeeded.png|'''Welsh Hill Speckled Face'''
Image:ImageNeeded.png|'''Welsh Mountain'''
Image:ImageNeeded.png|'''Wensleydale'''
Image:ImageNeeded.png|'''White Face Dartmoor'''
Image:ImageNeeded.png|'''White Faced Woodland'''
Image:ImageNeeded.png|'''Wiltshire Horn'''
Image:ImageNeeded.png|'''Zwartbles'''
<--Add more breeds here-->

</gallery>
==Capra Hircus==
<gallery widths="115px" perrow="5">
Image:ImageNeeded.png|'''Anglo-Nubian'''
Image:ImageNeeded.png|'''Angora'''
Image:ImageNeeded.png|'''Bagot'''
Image:ImageNeeded.png|'''Boer'''
Image:ImageNeeded.png|'''British Alpine'''
Image:ImageNeeded.png|'''British Saanen'''
Image:ImageNeeded.png|'''British Toggenburg'''
Image:ImageNeeded.png|'''Cashmere'''
Image:ImageNeeded.png|'''Saanen'''
Image:ImageNeeded.png|'''Toggenburg'''
<--Add more breeds here-->

</gallery>

[[Category:Lost]]

Small Ruminants Breeds - WikiNormals

2011-07-30T12:39:06Z

Ge8680:

<imagemap>
Image:Ovine Normals Breeds.jpg|200px|Small Ruminants Breeds
rect 0 0 650 301 [[Small Ruminants Breeds - WikiNormals]]
desc none
</imagemap>

{{toplink
|linkpage =WikiNormals
|linktext =WikiNormals

|pagetype =WikiNormals
|sublink1= Small Ruminants Section - WikiNormals
|subtext1= Small Ruminants Section
}}
==Ovine==
<gallery widths="115px" perrow="6">
Image:ImageNeeded.png|'''Badger Face Welsh Mountain'''
Image:ImageNeeded.png|'''Balwen Welsh Mountain'''
Image:ImageNeeded.png|'''Beltex'''
Image:ImageNeeded.png|'''Berrichon Du Cher'''
Image:ImageNeeded.png|'''Beulah Speckled Face'''
Image:ImageNeeded.png|'''Blackface'''
Image:ImageNeeded.png|'''Black Welsh Mountain'''
Image:ImageNeeded.png|'''Bleu Du Maine'''
Image:ImageNeeded.png|'''Bluefaced Leicester'''
Image:ImageNeeded.png|'''Border Leicester'''
Image:ImageNeeded.png|'''Boreray'''
Image:ImageNeeded.png|'''Brecknock Hill Cheviot'''
Image:ImageNeeded.png|'''British Inra 401'''
Image:ImageNeeded.png|'''British Milksheep'''
Image:ImageNeeded.png|'''Cambridge'''
Image:ImageNeeded.png|'''Castlemilk Moorit'''
Image:ImageNeeded.png|'''Charmoise Hill'''
Image:ImageNeeded.png|'''Charollais'''
Image:ImageNeeded.png|'''Cheviot'''
Image:ImageNeeded.png|'''Clun Forest'''
Image:ImageNeeded.png|'''Colbred'''
Image:ImageNeeded.png|'''Cotentin'''
Image:ImageNeeded.png|'''Cotswold'''
Image:ImageNeeded.png|'''Dalesbred'''
Image:ImageNeeded.png|'''Dartmoor (Greyface)'''
Image:ImageNeeded.png|'''Derbyshire Gritstone'''
Image:ImageNeeded.png|'''Devon Closewool'''
Image:ImageNeeded.png|'''Devon And Cornwall Longwool'''
Image:ImageNeeded.png|'''Dorset Down'''
Image:ImageNeeded.png|'''Dorset Horn & Poll Dorset'''
Image:ImageNeeded.png|'''Est A Laine Merino'''
Image:ImageNeeded.png|'''Exmoor Horn'''
Image:ImageNeeded.png|'''Friesland'''
Image:ImageNeeded.png|'''Gotland'''
Image:ImageNeeded.png|'''Hampshire Down'''
Image:ImageNeeded.png|'''Hebridean'''
Image:ImageNeeded.png|'''Herdwick'''
Image:ImageNeeded.png|'''Hill Radnor'''
Image:ImageNeeded.png|'''Icelandic'''
Image:ImageNeeded.png|'''Ile De France'''
Image:ImageNeeded.png|'''Jacob'''
Image:ImageNeeded.png|'''Kerry Hill'''
Image:ImageNeeded.png|'''Leicester Longwool'''
Image:ImageNeeded.png|'''Lincoln Longwool'''
Image:ImageNeeded.png|'''Llanwenog'''
Image:ImageNeeded.png|'''Lleyn'''
Image:ImageNeeded.png|'''Lonk'''
Image:ImageNeeded.png|'''Manx Loaghtan'''
Image:ImageNeeded.png|'''Masham'''
Image:ImageNeeded.png|'''Meatlinc'''
Image:ImageNeeded.png|'''Norfolk Horn'''
Image:ImageNeeded.png|'''North Country Cheviot'''
Image:ImageNeeded.png|'''North Ronaldsay'''
Image:ImageNeeded.png|'''Oxford Down'''
Image:ImageNeeded.png|'''Portland'''
Image:ImageNeeded.png|'''Romney'''
Image:ImageNeeded.png|'''Rouge De L'ouest'''
Image:ImageNeeded.png|'''Rough Fell'''
Image:ImageNeeded.png|'''Roussin'''
Image:ImageNeeded.png|'''Ryeland'''
Image:ImageNeeded.png|'''Scotch Halfbred'''
Image:ImageNeeded.png|'''Scottish Greyface'''
Image:ImageNeeded.png|'''Shetland'''
Image:ImageNeeded.png|'''Shetland-Cheviot'''
Image:ImageNeeded.png|'''Shropshire'''
Image:ImageNeeded.png|'''Soay'''
Image:ImageNeeded.png|'''Southdown'''
Image:ImageNeeded.png|'''South Wales Mountain'''
Image:ImageNeeded.png|'''Suffolk'''
Image:ImageNeeded.png|'''Swaledale'''
Image:ImageNeeded.png|'''Teeswater'''
Image:ImageNeeded.png|'''Texel'''
Image:ImageNeeded.png|'''Vendeen'''
Image:ImageNeeded.png|'''Welsh Hill Speckled Face'''
Image:ImageNeeded.png|'''Welsh Mountain'''
Image:ImageNeeded.png|'''Wensleydale'''
Image:ImageNeeded.png|'''White Face Dartmoor'''
Image:ImageNeeded.png|'''White Faced Woodland'''
Image:ImageNeeded.png|'''Wiltshire Horn'''
Image:ImageNeeded.png|'''Zwartbles'''
<--Add more breeds here-->

</gallery>
==Capra Hircus==
<gallery widths="115px" perrow="5">
Image:ImageNeeded.png|'''Breed'''
Image:ImageNeeded.png|'''Breed'''
Image:ImageNeeded.png|'''Breed'''
Image:ImageNeeded.png|'''Breed'''
Image:ImageNeeded.png|'''Breed'''
<--Add more breeds here-->

</gallery>

[[Category:Lost]]

UK - Bristol Veterinary School, Bristol

2011-07-09T10:19:18Z

Ge8680:

{{Vetschool
|Introduction=The University of Bristol Veterinary School is part of the University of Bristol's Faculty of Medical and Veterinary Sciences. The school occupies two sites. The Department of Pre-Clinical Veterinary Science, which is located on Southwell Street in West Bristol, is where the preclinical years (1-3) are based. The Department of Clinical Veterinary Science is some 14 miles away in the village of Langford, North Somerset. This site accommodates the clinical years (4-5). It is also home to the Langford Veterinary Service (LVS), which provides first opinion practice for all areas of the profession, as well as referral services for equine and small animals.
|History=The Department of Clinical Veterinary Science in Langford is based in the property and grounds of Langford House, which was originally developed as a farming estate by Simon Hill in 1877. The building, despite having been built in the mid-Victorian era, features distinctly Georgian architecture, as does much of the old city of Bristol. The Langford estate remained in the hill family until it was purchased by the Commissioners of Crown Lands in 1944. In 1951, it was acquired by the University of Bristol to be developed as a veterinary field station, and since then has been the site of clinical training for many generations of veterinary students. The School of Preclinical Veterinary Science is housed in the building of the old Kingsdown Grammar School, on Southwell Street, Bristol.
|Education=As well as the undergraduate Bachelor of Veterinary Science (BVSc) degree, the Vet School also provides numerous other undergraduate courses including Animal Behaviour and Welfare, Veterinary Nursing and Bioveterinary Science, Veterinary Cellular and Molecular Science, and Anatomical Science with Veterinary Anatomy. As well as these, it also accommodates postgraduate courses including PHd research posts and MSc in Meat Science and Technology. It also offers continuing education in the form of the RCVS Certificate in Advanced Veterinary Practice (CertAVP), and various other continuing professional development (CPD) courses.
|Research=The current major strategic aim of Bristol Vet School is to "develop internationally excellent cross-disciplinary research programmes in infectious diseases and food borne zoonoses that will fulfill the aspirations of the Selborne report and contribute to the UK Veterinary Schools collaborative research initiative." Within this initiative, current research is divided into four groups; Animal Behaviour & Welfare, Food Science & Safety, Infection & Immunity, and Matrix Biology.The new Animal Behaviour & Welfare building, designed by architects NVB and opened in January 2009, aims to achieve a BREEAM (Building Research Establishment Environmental Assessment Method) 'excellent' rating for sustainability, design, and energy usage. It looks to provide a focus for research sponsors from both the UK and Europe with an interest in sustainability.
|Clinical=Langford Veterinary Services, a culmination of the first opinion and referral practices at the School of Clinical Veterinary Science, is a dynamic, customer focussed veterinary business, providing an extensive range of specialist capabilities. All clinics are supported by highly specialised clinicians, diagnosticians, anaesthetists and nurses. The comprehensive and multi-disciplined referral service receives cases from both the South West and Wales, as well as further afield within the UK, while the first opinion practices service large areas of the South West, the Farm Animal Practice alone serving over 200 farm clients. The Langford Veterinary Service also offers an abbatoir service, and a behaviour clinic for treatment of pets with abnormal or undesirable behavioural traits.
|Image3=SAH.jpg
|Image2=sn.jpg
|MainImage=langfordHouse.jpg
|School=Bristol School of Veterinary Science
|Established=1951
|Location=Bristol
|Principal=Professor Jo Price BVSc MRCVS PhD
|BVSc Students=575
|Website=http://www.vetschool.bris.ac.uk
|Contact=
'''Langford (Clinical) Department''' 
Langford House 
Langford 
North Somerset 
UK 
BS40 5DU 
+44 (0)117 928 9562 
'''Bristol (Pre-clinical) Department''' 
Faculty of Medical and Veterinary Sciences 
Medical Sciences Building 
University Walk 
Bristol 
UK 
BS8 1TD 
+44 (0)117 33 11532 
}}

[[:Category:Vet Schools|View other vet schools]]

[[Category:Europe]]

UK - Bristol Veterinary School, Bristol

2011-06-17T13:14:25Z

Ge8680:

{{Vetschool
|Introduction=The University of Bristol Veterinary School is part of the University of Bristol's Faculty of Medical and Veterinary Sciences. The school occupies two sites. The Department of Pre-Clinical Veterinary Science, which is located on Southwell Street in West Bristol, is where the preclinical years (1-3) are based. The Department of Clinical Veterinary Science is some 14 miles away in the village of Langford, North Somerset. This site accommodates the clinical years (4-5). It is also home to the Langford Veterinary Service (LVS), which provides first opinion practice for all areas of the profession, as well as referral services for equine and small animals.
|History=The Department of Clinical Veterinary Science in Langford is based in the property and grounds of Langford House, which was originally developed as a farming estate by Simon Hill in 1877. The building, despite having been built in the mid-Victorian era, features distinctly Georgian architecture, as does much of the old city of Bristol. The Langford estate remained in the hill family until it was purchased by the Commissioners of Crown Lands in 1944. In 1951, it was acquired by the University of Bristol to be developed as a veterinary field station, and since then has been the site of clinical training for many generations of veterinary students. The School of Preclinical Veterinary Science is housed in the building of the old Kingsdown Grammar School, on Southwell Street, Bristol.
|Education=As well as the undergraduate Bachelor of Veterinary Science (BVSc) degree, the Vet School also provides numerous other undergraduate courses including Animal Behaviour and Welfare, Veterinary Nursing and Bioveterinary Science, Veterinary Cellular and Molecular Science, and Anatomical Science with Veterinary Anatomy. As well as these, it also accommodates postgraduate courses including PHd research posts and MSc in Meat Science and Technology. It also offers continuing education in the form of the RCVS Certificate in Advanced Veterinary Practice (CertAVP), and various other continuing professional development (CPD) courses.
|Research=The current major strategic aim of Bristol Vet School is to "develop internationally excellent cross-disciplinary research programmes in infectious diseases and food borne zoonoses that will fulfill the aspirations of the Selborne report and contribute to the UK Veterinary Schools collaborative research initiative." Within this initiative, current research is divided into four groups; Animal Behaviour & Welfare, Food Science & Safety, Infection & Immunity, and Matrix Biology.The new Animal Behaviour & Welfare building, designed by architects NVB and opened in January 2009, aims to achieve a BREEAM (Building Research Establishment Environmental Assessment Method) 'excellent' rating for sustainability, design, and energy usage. It looks to provide a focus for research sponsors from both the UK and Europe with an interest in sustainability.
|Clinical=Langford Veterinary Services, a culmination of the first opinion and referral practices at the School of Clinical Veterinary Science, is a dynamic, customer focussed veterinary business, providing an extensive range of specialist capabilities. All clinics are supported by highly specialised clinicians, diagnosticians, anaesthetists and nurses. The comprehensive and multi-disciplined referral service receives cases from both the South West and Wales, as well as further afield within the UK, while the first opinion practices service large areas of the South West, the Farm Animal Practice alone serving over 200 farm clients. The Langford Veterinary Service also offers an abbatoir service, and a behaviour clinic for treatment of pets with abnormal or undesirable behavioural traits.
|Image3=SAH.jpg
|Image2=sn.jpg
|MainImage=lang.jpg
|School=Bristol School of Veterinary Science
|Established=1951
|Location=Bristol
|Principal=Professor Jo Price BVSc MRCVS PhD
|BVSc Students=575
|Website=http://www.vetschool.bris.ac.uk
|Contact=
'''Langford (Clinical) Department''' 
Langford House 
Langford 
North Somerset 
UK 
BS40 5DU 
+44 (0)117 928 9562 
'''Bristol (Pre-clinical) Department''' 
Faculty of Medical and Veterinary Sciences 
Medical Sciences Building 
University Walk 
Bristol 
UK 
BS8 1TD 
+44 (0)117 33 11532 
}}

[[:Category:Vet Schools|View other vet schools]]

[[Category:Europe]]

Oestrous Cycle - Anatomy & Physiology

2011-04-09T12:40:41Z

Ge8680: /* Oestrous Cycle */

{{review}}

=Introduction=

Ovarian cycles are from oestrus to oestrus. Oestrus is the easily identifiable external marker. It should be noted that Oestrus is the noun and oestrous is the adjective.

= Classification of Oestrous Cycles =

== Based on Vaginal Cytology ==

=== Pro-Oestrus ===

* The phase immediately preceding oestrus.
* Lasts 2-5 days, depending on the species.
* Marked increase in reproductive activity.
* Endocrine transition from progesterone to oestrogen dominance under the influence of gonadotrophins LH and FSH.
* Follicular growth and [[Corpus Luteum Regression - Anatomy & Physiology|regression of the corpus luteum]] of the previous cycle (in polyoestrous species).
* Uterus enlarges slightly
* [[Uterus - Anatomy & Physiology#Endometrium|Endometrium]] becomes congested and oedematous, glands show secretory activity.
* [[Vagina and Vestibule - Anatomy & Physiology#Vagina_2|Vaginal]] mucous becomes hyperaemic.
** Increase in cell numbers in the [[Vagina and Vestibule - Anatomy & Physiology#Vagina_2|vaginal]] epithelium.
** Superficial layers become cornified.
* The '''[[Oestrous Cycle - Anatomy & Physiology#Bitch|bitch]]''' shows external evidence:
** [[Vagina and Vestibule - Anatomy & Physiology#Vulva|Vulval]] oedema
** Hyperaemia
** Sanguinous vulval discharge

=== Oestrus ===

* The period where the female will accept the male for [[Copulatory Behaviour - Anatomy & Physiology|copulation]].
* The onset and end of oestrus are the only stages of the oetrous cycle that can be accurately measured. They are therefore used to determine cycle length.
* Female seeks out the male and 'stands' to be mounted.
* [[Uterus - Anatomy & Physiology#Histology|Uterine]], [[Cervix - Anatomy & Physiology#Histology|cervical]] and [[Vagina and Vestibule - Anatomy & Physiology#Vagina_2|vaginal glands]] secrete increased amounts of mucus.
* Vaginal epithelium and [[Uterus - Anatomy & Physiology#Endometrium|uterine endometrium]] becomes hyperaemic and congested.
* [[Cervix - Anatomy & Physiology|Cervix]] is relaxed
* [[Ovulation - Anatomy & Physiology|Ovulation]] occurs during this phase in all domestic species except the cow.
** The cow [[Ovulation - Anatomy & Physiology|ovulates]] ~12 hours after the end of oestrus.
* [[Ovulation - Anatomy & Physiology|Ovulation]] is spontaneous in all domestic species except the cat, rabbit and camelids. In these species it is induced by the act of [[Copulatory Behaviour - Anatomy & Physiology|copulation]].
* During pro-oestrous and oestrus there is [[Ovary - Anatomy & Physiology#Folliculogenesis|follicular growth]] with no functional [[Corpus Luteum - Anatomy & Physiology|corpora lutea]] present on the [[Ovary - Anatomy & Physiology|ovary]] (aka follicular phase).
* The main ovarian hormone production is Oestrogen.

=== Metoestrus ===

* The phase after oestrus
* During early metoestrus, both oestrogen and progesterone levels are relatively low.
* Granulosa cells of the [[Ovulation - Anatomy & Physiology|ovulated]] [[Follicles - Anatomy & Physiology|follicles]] give rise to lutein cells, which are responsible for the [[Corpus Luteum Formation - Anatomy & Physiology|formation of the corpus luteum]] (luteinisation).
* Progesterone secretion is detectable soon after [[Ovulation - Anatomy & Physiology|ovulation]], with significant quantities produced in 2-5 days. This marks a transition from oestrogen to progesterone dominance.
* Reduction in secretion from [[Uterus - Anatomy & Physiology#Histology|uterine]], [[Cervix - Anatomy & Physiology#Histology|cervical]] and [[Vagina and Vestibule - Anatomy & Physiology#Vagina_2|vaginal glands]].

=== Dioestrus ===

* Longest phase of the oestrous cycle, which usually laste 10-14 days in polyoestrous females.
* The [[Corpus Luteum - Anatomy & Physiology|corpus luteum]] is present on the [[Ovary - Anatomy & Physiology|ovary]] and secreting large amounts of progesterone. The duration of this phase is directly related to the time that the corpus luteum remains functional.
* High progesterone levels prompt the uterus to prepare a suitable environment for development of the embryo, and eventual [[Implantation - Anatomy & Physiology|attachment of the conceptus to the endometrium]] (implantation).
* Uterine glands undergo hyperplasia and hypertrophy.
* [[Cervix - Anatomy & Physiology|Cervix]] becomes constricted
* Secretions of the tract are scant and sticky.
* [[Vagina and Vestibule - Anatomy & Physiology#Vagina_2|Vaginal mucosa]] becomes pale.
* Ends with the [[Corpus_Luteum_Regression|regression of the corpus luteum]] (luteolysis).

=== Anoestrus ===

* Genital system is quiescent
* Follicular development is minimal and corpora lutea have regressed and are non-functional.
* Secretions are scanty
* [[Cervix - Anatomy & Physiology - Anatomy & Physiology|Cervix]] is constricted
* Vaginal Mucosa is pale

== Based on Secretory Patterns of the Ovary ==

=== Follicular Phase ===

* Begins after luteolysis, which causes the decline in progesterone.
* Gonadotrophins LH and FSH are produced, which cause ovarian follicles to produce Oestrogen.
* Ends at ovulation.
* Oestrus is designated as day 0.

=== Luteal Phase ===

* Begins after ovulation
* Includes the development of corpora luta, which produce progesterone.
* Includes luteolysis, which is brought about by Prostaglandin F2α.

== Based on Vaginal Cytology ==

=== Proliferative Phase ===

* Oestrogen dominant
* Includes proliferation of the [[Uterus - Anatomy & Physiology#Endometrium|endometrium]].

=== Secretory Phase ===

* Progesterone dominant
* Includes secretions from the uterus, such as 'uterine milk' to sustain the fertilised ovum until implantaion.

=Comparative Oestrous Cycles=

{| style="width:75%; height:200px" border="1"

!'''Species'''
!'''Mare'''
!'''Cow'''
!'''Sow'''
!'''Ewe'''
!'''Bitch'''
!'''Queen'''
|-
| '''Length of Oestrous Cycle (days)'''
| 21
| 21
| 21
| 17
| 93
| Variable
|-
| '''Duration of Oestrus'''
| 4-8 days
| 12-36 hours
| 48-96 hours
| 24-48 hours
| 7-13 days
| 4-10 days
|-
| '''Duration of Follicular Phase (days)'''
| 7 (variable)
| 4
| 7
| 3
| 18
| Variable
|-
| '''Duration of Luteal Phase (days)'''
| 14
| 17
| 14
| 14
| 75
| 40
|
|}

== Mare ==

=== Oestrous Cycle ===

* Seasonal breeder (long day)
* Oestrous cyclicity from spring-autumn. During the winter, the mare is normally anoestrus.
* Winter anoestrus is follwed by a transition to regular cyclic activity. During this time, the duration of oestrus may be irregular or very long.
* Before the first ovulation, behavioural oestrus may not be accompanied by the presence of palpable follicles on the ovary.
* Some long oestrus periods in spring are anovulatory.

* Average cycle length is 20-23 days. The cycles are longest in spring and shortest from June-September.
* Oestrus lasts 6 days.
* Dioestrus lasts 15 days.
* Ovulation occurs on the penultimate day or last day of oestrus.
* The diameter of a ripe follicle ready to ovulate is 3-7cm. The day before ovulation, the tension in the follicle is reduced. Palpation of a large, fluctuating follicle is a reliable sign of impending ovulation.

* The onset of oestrus after foaling is known as the 'foal heat'.
* Occurs on day 5-10 post-parturition.
* Sometimes shorter than normal, lasting 2-4 days.
* The first two post-parturient cycles are a few days longer than normal.

* During Oestrus, a single egg is usually released. Thus, the mare is monotocious.
* Ovulation seems to occur more frequently from the left ovary.
* All ovulations occur from the ovulation fossa.
* Due to the reversed structure of the ovary, corpora lutea may only be seen sometimes at the ovarian hilus. However, because the ovary is curved and mostly covered by fimbrae of the oviduct, corpora lutea cannot be identified by rectal palpation.
* Only fertilized eggs can pass into the uterus.
* Non-fertilized eggs remain in the Utero-Tubal junction for months, where they finally disintegrate.

=== Cyclic Changes in the Ovaries ===

* Just before the onset of oestrus, several follicles enlarge to 1-3cm.
* By the first day of oestrus, one dominant follicle is significantly larger than the others, with a diameter of 2.5-3.5 cm.
* During oestrus, this dominant follicle matures and ruptures once it has attained a diameter of 3-7 cm.
* Several hours before ovulation, the ripe follicle becomes much less tense and can be recognised as an indentation on the surface of the ovary.
* There is usually haemorrhage into the follicle and the coagulum hardens within the next 24 hours.
* After ovulation, the other follicles regress.
* During the first 4-9 days of dioestrus, there are no follicles over 1cm present on the ovary.
* For 3 days after ovulation, the leutinising mass can be felt, but later it normally has the same texture as the ovary.
* The corpus luteum reaches full size at 4-5 days after ovulation but does not protrude from the ovarian surface.
* On section of the ovary, the corpus luteum will appear brown and later yellow. It is triangular or conical in shape, with the narrow end on the ovulaiton fossa. The centre of the corpus luteum normally contains dark brown fibrin.
* The corpus luteum of the cycle (non-pregnant) starts to regress on about the 12th day of the cycle. At the time of [[Corpus_Luteum_Regression|regression]], there is a fall in blood progesterone concentration.

* During winter anoestrus, both ovaries are usually small and bean-shaped. They normally measure:
** 6cm pole-pole
** 4cm from the hilus to the free border
** 3 cm side-side
* During the cycle, the size of the ovary depends on the number and size of the follicles.
* During oestrus, the ovary may contain 2-3 follicles. These can each measure 4-7 cm. These, combined with other less developed follicles, give the ovary a huge size.
* During Dioestrus, there is an active corpus luteum and atretic follicles present. However, these only give the ovary a size a little larger than in Anoestrus.

=== Endocrine Changes During the Oestrous Cycle ===

* Biphasic secretion of FSH with surges every 10-12 days.
** One surge after ovulation and a second in mid-late Dioestrus (~10 days before the next ovulation).
* This increase in FSH secretion is unique to the mare.
** Primes the development of a new generation of follicles, one of which will ovulate during the next oestrus.
* The pattern of LH secretion is also unusual.
** No dramatic LH surge prior to ovulation.
** LH gradually increases and elevated levels then persist for 5-6 days either side of ovulation.
* Oestrogens reach peak values during oestrus.
* Progesterone concentrations follow the changes of the corpus luteum closely.

== Cow ==

=== Oestrous Cycle ===

* Polyoestrous
* The first ovulation in heifers is usually without behavioural oestrus. This is termed 'silent heat'.
* Cyclical activity persists except during pregnancy, for 3-6 weeks post-calving and during high milk yield.
* In heifers, the average length of the oestrous cycle is 20 days (18-22).
* In cows, the average length of the oestrous cycle is 21 days (18-24).
* The average duration of oestrus is ~ 15 hours (2-30 hours).
* The body temperature of dairy cows falls by ~0.5◦C the day before oestrus. It then increases in oestrus before falling by ~0.3◦C at ovulation.
* Vaginal pH also fluctuates throughout the oestrous cycle, but is lowest (7.32) on the day of oestrus.
* Ovulation is spontaneous, occuring ~12 hours after the end of oestrus.
* Within 2 days of service, there is yellow-white vulval discharge of mucus. This contains neutrophil leucocytes from the uterus.
* At ~48 hours post-oestrus, irrespective of service, there is a bright red sanguineous discharge from the uterine caruncles.

=== Cyclic Changes in the Vagina ===

The main variations are in the epithelial cells of the anterior vagina and in the secretory function of the cervical glands.
* Oestrus: Anterior vaginal epithelium becomes greatly thickened due to cell division and the growth of the tall, columnar, mucus-secreting superficial cells.
* Dioestrus: Cells of the cranial vaginal epithelium vary from flat to low columnar. Invasion of the vaginal mucosa by leucocytes is maximal 2-5 days after oestrus.
* Copious secretion of mucus by the cervix and anterior vagina begins 1-2 days before oestrus.
* Secretions diminish to the 4th day after oestrus.
* Mucus is transparent and flows readily.
* Variations in cervical mucus:
** During oestrus and for a few days after, crystals are disposed in a distinct aborisation pattern.
** For the remainder of the cycle this pattern is absent.
** This pattern, and the amount of cervical mucus depends on oestrogen concentration.
* Postoestrous vaginal mucus:
** Floccules of leucocytes
** Blood is frequently present
* Hyperaemia of vaginal and cervical mucosae is progressive during pro-oestrus and oestrus.
* At this time, the protrusion of the cervix into the cranial vagina is relaxed, so that 1-2 fingers can be inserted into the cervical os.
* During metoestrus, there is a rapid reduction in vascularity.
* From day 3-5 postoestrus:
** Mucosa of the cervix is pale and quiescent.
** The external os is constricted.
** Mucus becomes scanty, sticky and pale yellow/brown.
* There are also cyclical changes in the vaginal pH:
** pH falls from 7.0 to 6.72 one day before first signs of behavioural oestrus.
** At the start of oestrus, pH falls again to 6.54.

=== Cyclic Changes in the Uterus ===

* Oestrus:
** Uterus is congested
** [[Uterus - Anatomy & Physiology#Endometrium|Endometrium]] contains oedematous fluid, which causes its surface to glisten.
** Muscularis is contractile, so when palpated per rectum, the uterus feels turgid and the horns feel erect and coiled.
*** Tonicity is present the day before and the day after oestrus, but is at its maximum during heat.
** Marked increase in vascularity
* 24-48 hours postoestrus:
** Uterine caruncles show petechial haemorrhage. This gives rise to the discharge of blood from the vagina.
*** In heifers, there is also often perimetral subserous petechiae.
* Dioestrus:
** [[Uterus - Anatomy & Physiology#Endometrium|Endometrium]] is covered with scanty secretion from the uterine glands.

=== Cyclic Changes in the Ovaries ===

* Usually one follicle ovulates, but twin ovulations occur in 4-5% of cows and triplet ovulations more rarely.
* In dairy cattle 60% of ovulations are from the right ovary, but in beef cattle, they are about the same.
* Size of the ovaries is dependent on the phase of the oestrous cycle.

==== Follicular Growth and Development ====

* There is follicular growth and atresia throughout the oestrous cycle.
* There are normally two waves of follicular growth, but 3 waves also commonly occur:
** One begins on day 3-4
** The second begins on day 12-14
* A normal follicle of 9-13mm is present between day 5-11 before becoming atretic.
* In the second wave, an ovulatory follicle develops, measuring 9-13mm between day 15-20.
* Ovulatory follicle is selected ~3 days prior to ovulation.
* Follicular growth is under the influence of FSH.
* One follicle normally obtains dominance and subsequently ovulates.
* Dominance does not involve inhibin. It is probably due to an intra-ovarian mechanism which does not suppress FSH secretion. Other hormones such as IGF-1 (Insulin-like growth factor-1) may also be involved in follicular growth patterns.
* During dioestrus, there are several large follicles on the ovary. These range in size 0.7-1.5cm in diameter. These follicles do not alter the contours of the ovaries, but cause variation in size.
* During Pro-oestrus and oestrus, the dominant follicle enlarged and ovulation occurs once it is at least 1.9cm.
* The ripening follicle is detectable by rectal palpation during heat.
** It can be felt as a soft, bulging area on the surface of one ovary.
* Ovulation can occur from anywhere on the ovarian surface.
* The shape of the ovary when the corpus luteum develops will depend on the site of ovulation.
* The point of ovulation is usually an avascular area of the follicular wall. Therefore, haemorrage of the follicle is not seen with ovulation in the cow. However, after ovulation there is congestion around the point of follicular rupture and sometimes there is a small blood clot in the centre of the new corpus luteum.
* When the follicle ruptures, the ovum is expelled through a small breach in the surface.
* Most of the antral fluid escapes and the follicle collapses.
* The ovary feels flattened and soft on palpation.
* The surface from which ovulation has occurred is wrinkled and may be blood-stained.

==== Corpus Luteum of the Oestrous Cycle ====

* The corpus luteum develops by hypertrophy and luteinization of the follicular granulosa cells, this occurs rapidly.
* By 48 hours after ovulation, the corpus luteum is ~1.4cm in diameter. It feels soft and yields on palpation.
* It is dull cream in colour and the luteinized cells can be seen in loose pleats.
* It attains its maximum size by day 7-8 of dioestrus.
* Luteinized pleats are now compact.
* The body is a homogenous mass that is yellow/orange in colour.
* The shape varies, most are oval but they can be square or rectangular.
* Sometimes the centre is occupied by a cavity which is occupied by yellow fluid. This is known as a cyctic corpus luteum, but is rarely pathogenic and usually completely normal.
* If a cavity is present, it must be distinguished from a luteinisation of the walls of the follicle without ovulation (abnormal).
** If it is a corpus luteum with a cavity, there will be a pin-head depression in the centre of the projection from the surface of the ovary. This depression indicates ovulation has occured.

==== Projection of the Corpus Luteum from the Surface of the Ovary====

* As the corpus luteum enlarges, it pushes itself out of the ovary and so stretches the ovarian surface as it does so.
* By the time it reaches maximum development it often forms a disctinct projection from the surface of the ovary.
* Usually, this is a distinct bulge about 1cm in diameter with a clear-cut constriction where it joins the general contour of the ovary.
* Sometimes, it is nipple like.
* Another type of projection is indistinct and diffuse, occupying the greater part of the ovary.
* The type of protrusion depends on the extent of the ovarian surface that was occupied by the follicle just before ovulation.

==== Regressing Corpus Luteum ====

* The corpus luteum remains its maximum size until the onset of pro-oestrus (~24 hours before heat).
* When the cow comes into heat, the corpus luteum undergoes rapid reduction in size and changes colour and appearance.
* By the middle of oestrus, its diameter is reduced to 1.5cm and its protrusion from the surface of the ovary is less distinct. Also, its colour changes to bright yellow. (It is after this discovery in the cow that the corpus luteum was given its name. Corpus luteum is latin for 'yellow body').
* Its consistency is dense and it becomes invaded with scar tissue.
* By the second day of dioestrus, it is reduced to ~1cm and its outline is becoming irregular.
* The colour then changes from yellow to brown.
* By the middle of dioestrus, it has shrunk to 0.5cm and its protrusion from the ovarian surface is a bit larger than a pin-head.
* As it ages, its colour goes from red to scarlet.
* Small remnants can persist for several months.
* For more general information on regression of the corpus luteum, click [[Corpus_Luteum_Regression|here]]

==== Size of Ovaries ====

* Depends on the phase of the oestrous cycle and whether it contains an active corpus luteum.
* The presence of follicles does not alter the size of the ovary to anything like the extent of the corpus luteum.
* In the majority of heifers and young cows examined between day 6-18 of dioestrus, one ovary will be larger than the other.
* The larger ovary will be approximately:
** 3.5cm pole-pole
** 3cm from the attached side to the free border
** 2.8cm from side to side
** The corpus luteum will project from some point on the surface.
* The smaller ovary will be approximately:
** 2.5cm pole-pole
** 1.5cm from the attached side to the free border
** 1.2 cm from side to side
* During the 4-5 days after oestrus, the developing corpus luteum has not attained sufficient bulk to influence the size of the ovary significantly and the regressing corpus luteum has lost significant bulk.
* During oestrus there will also be little difference in size.
** If the ovary undergoing enlargement of a dominant follicle also contains a regressing corpus luteum, it will be a little larger than the other ovary but not strikingly so.

==== Ovaries in a Multiparous Cow ====

* Larger
* Partly due to progressive deposition of scar tissue from prolonged function.
* Can be due to large numbers of small, but visible follicles.
* Often, the ovary that does not contain a corpus luteum measures:
** 4cm pole-pole
** 3cm from the fixed edge to the free border
** 2cm from side to side
* In mid-dioestrus it is still possible to detect the corpus luteum because, aside from its protrusion, the ovary appears plump. The ovary that does not contain a corpus luteum is flattened from side to side.
* Corpora lutea (active and regressing) and follicles approaching maturity are the same as those in the heifer.
* In addition, however, there are old scarred corpora lutea of previous pregnancies.
** Generally white (corpus albicans - latin for white body), pin-head sized projections on the surface of the ovary.
** Contain mainly scar tissue
** Irregular outline
** Maximum of 0.5 cm
* The corpus luteum of pregnancy does not atrophy as quickly after parturition as the corpus luteum of the cycle. It becomes invaded by scar tissue and remains throughout the cow's life.
* The fully developed corpus luteum is present by day 7 and persists unchanged until the onset of pro-oestrus at day 19-20.

==== Appearance of the Ovaries on Ultrasound ====

* Normal structures that can be identified:
** Ovarian stroma: Mottled echotexture
** Antral follicles: Anechoic (black) structures of variable size with a clear definition between the follicular wall and the antral cavity. They will not always be a regular, spherical shape.
** Corpora lutea: Well defined border and a mottled echogenic appearance. They are less echogenic than the ovarian stroma. The fluid-filled lacuna can be identified as a dark, non-echogenic area in the centre.
** Ovarian blood vessels: Black,non echogenic structures which are easily confused with antral follicles. Movevement of the transducer can be used to differentiate the two, as this shows their elongated structure.
* In addition, pathological structures like ovarian cysts can be seen.

=== Endocrine Changes during the Oestrous Cycle ===

* Hormones are secreted in a pulsatile manner and fluctuate considerably.
* Just before onset of behavioural oestrus, there is a sharp rise in plasma oestrogens, particularly oestradiol.
** Peak values occur at the beginning of oestrus
** Levels decline to basal concentrations at ovulation
* During the rest of the cycle, there are fluctuations but there is a discrete peak around day 6 of the cycle.
** Related to the first wave of follicular growth
* Pre-oestrus rise in oestrogens stimulates the LH surge from the anterior pituitary.
** This is necessary for follicular maturation, ovulation and maturation of the corpus luteum.
* A second, less discrete peak occurs 24 hours after the LH surge.
* Changes in progesterone concentrations mimic changes in the corpus luteum.
* Progesterone levels peak 7-8 days after ovulation and decline quickly from day 18.
* When progesterone levels fall to low basal levels, the negative feedback on the pituitary gland is removed. This allows a sudden release of gonadotrophins.

== Ewe ==

=== Oestrous Cycle ===

* Short day breeders (oestrous cycles commence in response to decrease in day length).
* In Britain, sheep cycle from October-February, during which time there are 8-10 recurrent oestrous cycles.
* Ewe lambs and yearling ewes have shorter breeding seasons than older ewes.
* The length of the oestrous cycle is about 17 days.
* Duration of oestrus in most British breeds is ~30 hours and is at least 10 hours in immature ewes.
* In merino sheep, behavioural oestrus (heat) may last 48 hours.
* Ovulation occurs towards the end of oestrus.

=== Cyclic Changes in the Ovaries ===

* Ovaries are smaller than those of the cow and their shape is more spherical.
* During anoestrus they measure approximately:
** 1.3 cm pole-pole
** 1.1. cm from the fixed edge to the free margin
** 0.8 cm from side to side
* Transrectal ultrasound is difficult, because the ovaries are difficult to access. Therefore, folliculogenesis is much harder to visualise than in the cow.
* The ewe is similar to the cow, with 3-4 follicular waves in each oestrous cycle.
** If there are 3 follicular waves, two will occur during the luteal phase and one during the follicular phase.
* Even during anoestrus, dominant follicles will reach the same size as those present during cyclical activity.
* At the onset of oestrus, one or more follicles reach a size of 1cm.
** Follicular walls are thin and transparent.
* Rupture of the follicle at ovulation is preceded by the elevation of a small papilla above the general surface.
* Ovulation occurs through rupture of this papilla ~24 hours after the onset of heat.
* There is rapid development of the corpus luteum.
** Development is linear from day 2-12 after ovulation.
* By day 5 of dioestrus, the corpus luteum is 0.6cm in diameter.
* It then attains a maximum size of 0.9cm diameter and has a central cavity.
* Over the period of dioestrus, the colour changes from blood red to pale pink. The size stays constant until the onset of the next oestrus.
* At the onset of the next oestrus:
** Regression of the corpus luteum of the previous cycle is rapid
** Colour changes to yellow and then brownish-yellow.
* The luteolytic mechanism is similar to in the cow.
** At the end of dioestrus, under the influence of oestradiol and progesterone, there is an increase in the number of uterine oxytocin receptors.
** At the same time, the corpus luteum produces oxytocin, which stimulates PGF2α. PGF2α then acts to stimulate the release of oxytocin in a feedback loop mechanism.
* The first corpora lutea formed after the first ovulation at the start of the breeding season have a shorter lifespan than subsequent ones.
* In twin ovulations, the two corpora lutea can occupy the same or opposite ovaries.
* During pregnancy:
** The corpus luteum is 0.7-0.9 cm in diameter.
** It is pale pink in colour
** The central cavity that is seen in cyclic corpora lutea has disappeared and is filled with white tissue.
* Ovulation with corpus luteum formation but without heat may occur in the anoestrus period. This is known as spurious ovulation.
* The number of ova shed at each oestrus is dependent on genetic and nutritional factors.

=== Endocrine Changes during the Oestrous Cycle ===

* Just before the onset of oestrus, there is a rise in oestrogens, particularly oestradiol 17β.
* This is follwed by an LH surge, which peaks at ~14 hours before ovulation.
* At the same time as LH peaks, there is a rise in FSH.
* There is also a second peak in FSH two days after ovulation.
* Progesterone concentrations closely follow changes in the corpora lutea.
** Maximum progesterone concentrations are lower than those of the cow.
* Prolactin fluctuates throughout the oestrous cycle.
** Concentrations rise during oestrus and ovulation
** This pattern reflects the role of prolactin in formation of the corpus luteum.

== Nanny Goat ==

=== Oestrous Cycle ===

* Breeding season in Britain is August-February with greatest activity in October, November and December. However, closer to the equator, does will cycle all year round.
* Polyoestrous
* Interoestrous interval of 20-21 days, but this is irregular at the start of the breeding season.
* Duration of oestrus is 30-40 hours.
* Ovulation occurs 12-36 hours after the onset of oestrus.

=== Cyclic Changes in the Ovaries ===

* Ovaries vary in shape, depending on the stuctures present.
** The longest dimention is ~2.2cm.
* The largest follicles reach a maximum diameter of ~1.2cm.
* When these follicles protrude from the surface of the ovary, they often have a bluish tinge.
* There are four follicular waves of growth, with ovulation occuring during the fourth wave.
* Corpora lutea are pink in colour

=== Endocrine Changes during the Oestrous Cycle ===

* Endocrine changes are the same as in the ewe.

== Sow ==

=== Oestrous Cycle ===

* The domestic sow is generally polyoestrous, but the wild pig is a seasonal breeder with the main breeding season occuring in autumn with another peak in April.
* There is some influence of photoperiod on reproduction in the domestic sow.
** Anoestrus occurs more commonly in summer and less commonly in February and March.
** Ovulation rate is lower in summer.
** Artificially reducing the day length from May-August will decrease the interval from weaning to oestrus from 23.6 days on average to 5.7 days.
* The oestrous cycle normally lasts 21 days, interrupted only by pregnancy and lactation.
** During lactation, the physical stimuli of suckling will suppress cyclic activity.
* Oestrus normally lasts ~53 hours.
* Ovulation occurs 38-42 hours after the onset of oestrus.
* Many sows show an anovulatory oestrus 2 days after farrowing.
* When weaning occurs at 5-6 weeks, oestrus occurs within 4-6 days.
* Earlier weaning results in a slightly longer interval before subsequent oestrus.

=== Cyclic Changes in the Ovaries ===

* The ovaries of a mature, cyclic sow are large and look like mullberries.
** Surface lobulations are due to elevations of large follicles and corpora lutea.
* When mature, follicles reach a diameter of 0.8-1cm.
* When mature, corpora lutea reach a diameter of 1-1.3 cm.
* It is difficult to study follicular dynamics in a sow because it is hard to identify a single follicle due to the large number present.
* Except during the follicular phase, there is continuous proliferation and atresia of follicles.
* There is normally a pool of about 50 follicles 2-5mm in diameter at any one time.
* Between day 14-16 of the cycle,there is follicular recruitment under the influence of gonadotrophins.
** This is possible due to a decline in progesterone, and subsequent withdrawal of negative feedback.
* A large number of these recruited follicles are destined for ovuation.
* At day 21-22 it is possible to identify the pre-ovulatory population.
* The growth of pre-ovulatory follicles during this follicular phase is associated with rapid atresia of small follicles. There is also a block to replacement of atretic follicles within the proliferating pool, so there must be some ovarian control mechanism. What exactly this mechanism is is currently unknown, but various substances have been proposed, including:
** Steroids
** Growth factors
** Growth factor binding proteins
** 'Follicle regulatory protein'
* The ripe follicle is a 'se-shell pink' colour. It has a fine network of surface blood vessels and one point which is very transparent. This transparent point indicates the site of imminent ovulation.
* Haemorrhagic follicles are common.
* After ovulation, a considerable number of follicles ~ 0.4cm remain on the ovary. Some of these enlarge gradually to 0.9cm by day 18.
* Immediately after ovulation, the ruptured follicle is seen as a congested depression on the ovary.
* Accumulation of blood clot soon gives the ruptured follicle a conical shape.
* By day 3 after ovulation, its cavity is filled with a dark red blood clot.
* By day 6, the blood clot is replaced by a connective tissue plug, or slightly yellow fliud.
** Clots may persist up to day 12.
** Fluid may persist up to day 18.
* Corpora lutea attain maximum size at 12-15 days post-ovulation.
* After this, they gradually regress to the next oestrus.
* They are dark red up to day 3.
* They then change colour and remain 'wine red' up to day 15.
* As the corpus luteum regresses between days 15-18, the colour rapidly changes to yellow, creamy yellow or buff.
* The mechanism of luteolysis is not fully understood in the sow.
** Corpora lutea are unresponsive to PGF2α until 12-23 days after ovulation.
** During luteolysis, corpora lutea are invaded by macrophages.
** Macrophages produce Tumour Necrosis Factor (TNF).
** TNF and PGF2α probably work together to cause luteolysis.
** TNF also inhibits oestradiol production, thus eliminating the luteotrophic source.
* There is rapid regression of corpora lutea at the next oestrus, but throughout the next dioestrus the corpora lutea remain as distinct entities.
* After this they rapidly regress to grey pin-head foci on the ovary.
* During the luteal phase of the cycle, oestrogens are luteotrophic. This may prolong the lifespan of the corpora lutea for several weeks. The result of this is pseudopregnancy.

=== Endocrine Changes during the Oestrous Cycle ===

* Oestrogens start to rise at the time of corpora lutea regression.
* Oestrogens reach a peak about 48 hours before the onset of oestrus.
* The ovulatory LH surge occurs at the start of oestrus, 8-15 hours after the peak in oestrogen.
* LH concentrations remain low and fluctuate throughout the rest of the cycle.
* FSH value vary considerably, but there are two surges.
** One surge is concurrent with the LH peak.
** A larger surge occurs on day 23 of the cycle.
* Progesterone concentrations closely follow changes of the corpora lutea.
** In the first 8 days post-ovulation, there is good correlation between progesterone concentrations and the number of corpora lutea present.
** By day 12 post-ovulation, the correlation is less obvious.
* There are two surges of prolactin.
** One surge occurs at the same time as the LH and oestrogen surge.
** A second surge occurs during oestrus.

== Bitch ==

=== Oestrous Cycle ===

* Monoestrous, with no seasonal influence.
* A single very long cycle, follwed by a long period of anoestrus.
* Cycle about 3 times every 2 years.
* The luteal phase is about the same length as gestation (~60 days), so pregnancy does not affect the length of the oestrous cycle. Thus, no luteolytic mechanism is required.

==== Pro-oestrus ====

* Characterised by vulval oedema, swelling and sanguinous discharge.
** May not always be visible because some bitches will continually lick the perineum.
* Bitch is attractive to males, but will not accept them.
* Duration is ~9 days

==== Oestrus ====

* Accepts the male
* Vulva becomes less oedematous
* Vulval discharge lessens and becomes more clear.
* Duration is ~9 days
* Ovulation usually occurs 1-2 days after the onset of oestrus.
** Some follicles continue to ovulate 14 days later.

==== Metoestrus ====

* Starts when the bitch will no longer accept the dog.
* There is dispute over the duration of this phase, with two main theories:
** Ends when corpora lutea have regressed at 70-80 days.
** Ends when endometrial repair is complete at 130-140 days.

==== Anoestrus ====

* Transitions from metoestrus to anoestrus with no external signs.
* This is also true after parturition.
* Lasts about 3 months before return to pro-oestrus.

=== Cyclic Changes in the Uterus ===

* The [[Uterus - Anatomy & Physiology#Endometrium|endometrium]] shows considerable change during the oestrous cycle.
* In pro-oestrus and oestrus, endometrial glands are loosely coiled with obvious lumina and a deep epithelial lining.
* During metoestrus, the glands become larger. Lumina become smaller and the basal layer of the [[Uterus - Anatomy & Physiology#Endometrium|endometrium]] becomes more tortuous.
* As the bitch reaches anoestrus, there is a reduction in the number of glands and the amount that they coil.
* In metoestrus (~98 days after the onset of oestrus), there is desquamation of the [[Uterus - Anatomy & Physiology#Endometrium|endometrial]] epithelium.
* By day 120-130, the [[Uterus - Anatomy & Physiology#Endometrium|endometrium]] is restored by proliferation of cells from crypts of the endometrial glands.

=== Cyclic Changes in the Ovaries ===

==== Anoestrus ====

* In anoestrus, the ovaries are oval and slightly flattened.
* In a medium sized breed, they measure approximately:
** 1.4cm pole-pole
** 0.8 cm from the attached end to the free border
* No follicles can be seen.
* On section, tiny remnants of the corpora lutea of previous cycles are visible as yellow/brown spots.

==== Pro-oestrus ====

* Developing follicles are about 0.5cm in diameter.
* They enlarge until ovulation, where their size is 0.6-1cm.

==== Oestrus ====

* By the time of ovulation, the ovary is enlarged.
* The size of the ovary depends on the number of ripe follicles present.
* The shape of the ovary becomes irregular due to the projection of follicles from its surface.
* The follicle wall is thick, so it is hard to distinguish between follicles and corpora lutea.
* Prior to ovulation, the surface of follicles shows a slightly raised papule. This is about the size of a pin-head. Also, the epithelium covering this papule is brown, whereas the rest of the follicle is flesh-coloured.
* A unique feature of the bitch follicle is the thickness of its wall.
** Due to hypertrophy and folding of granulosa cells which is visible to the naked eye.
** This is evidence of pre-ovulatory luteinization.
* Spontaneous ovulation usually occurs 1-2 days after oestrus onset.
* Most follicles rupture over a period of 48 hours.
* The oocyte can be fertilized for up to 108 hours after ovulation.

==== Metoestrus ====

* At first, the corpus luteum contains a central cavity.
* By day 10 after ovulation, the cavity becomes filled by compact luteinised cells.
* At this time, the corpus luteum reaches its full size, measuring 0.6-1.0 cm.
* Corpora lutea comprise the greater mass of the ovary.
* Generally, equal amounts of corpora lutea are found on each ovary.
** The number of foetuses in the uterine horns frequently differ from the number of corpora lutea on the ovaries of their respective sides.
** Embryonic migration to the uterine horn of the opposite side is common.
* On section:
** Corpus luteum is yellow-pink
** It remains unchanged in the non-pregnant bitch until about day 30 after ovulation.
** It then slowly atrophies
** During pregnancy, corpora lutea persist at their maximum size thoughout the pregnancy, but regress rapidly after parturition.

=== Appearance of the Ovaries on Ultrasound ===

* Developing antral follicles can be seen at the beginning of pro-oestrus.
** Appear circular and anechoic
* In oestrus, antral follicles are increased in size, reaching a maximum diameter of 4-13mm on day 13 (day 0 is the onset of pro-oestrus).
* From day 10 onwards, walls of the follicles become thickened due to pre-ovulatory luteinisation.
* No evidence of follicular collapse associated with ovulation.
* 25-30 days after the onset of pro-oestrus, the ovaries are difficult to identify.

=== Endocrine Changes during the Oestrous Cycle ===

* The luteal phase is prolonged compared to other species, this is shown by persisting levels of progesterone in the bloodstream.
* Progesterone levels begin to rise 60-70 hours before ovulation has occured. This is evidence of pre-ovulatory luteinisation of mature follicles.
* The pre-ovulatory rise in progesterone may signal the bitch to accept the male.
* Oestrogens rise rapidly before the onset of standing oestrus.
* The LH surge rapidly follows and lasts longer than in other species.
* Ovulation occurs 24-96 hours after the LH surge.
* FSH levels peak at the same time as the LH surge.
* As progesterone levels fall towards the end of metoestrus or pregnancy, prolactin increases.
* Prolactin is a major luteotrophic hormone in the bitch.

=== Pseudopregnancy ===

* Almost all bitches show some evidence of pseudopregnancy during metoestrus.
** Covert pseudopregnancy: where the bitch is in metoestrus, but shows little or no signs.
** Overt pseudopregnancy: where the bitch shows signs ranging from slight mammary development and lactogenesis to mock-parturition with nesting, loss of appetite, straining, emotional attachment to inanimate objects and heavy lactation.
* There is no difference in progesterone concentrations in bitches with or without pseudopregnancy.
* Prolactin is probably responsible for initiating the changes.

== Queen ==

=== Oestrous Cycle ===

* Seasonally polyoestrous
* Long day breeders with a period of anoestrus beginning in late autumn.
* Increasing daylight is the most important factor for inducing the resumption of reproductive activity. The first oestrus will usually occur soon after the shortest day of the year.
* If constant 14 hours of daylight is provided, the queen will continue to cycle all year round.
* Some non-pedigrees have regular oestrous cycles lasting about 3 weeks, but others show no regular pattern.
* Duration of oestrus is 7-10 days regardless of mating.

* Oestrogen concentrations increase dramatically at the time of oestrus and may double over 24 hours.
* The principle oestrogen is Oestradiol 17β.
* The rise in Oestradiol 17β corresponds with behavioural oestrus, there are no external signs of pro-oestrus.

=== Mating and Ovulation ===

* The queen is an induced ovulator, so [[Cat Copulatory_Behaviour - Anatomy & Physiology|mating]] is important in triggering ovulation.
* There are receptors in the vulva, which are stimualated by [[Cat Copulatory_Behaviour - Anatomy & Physiology|copulation]].
* This results in release of LH fromt he anterior pituitary gland.
* Only 50% of queens ovulate after a single mating, because multiple ovulations are usually required for adequate LH release.
* The ovulatory LH surge begins within minutes of coitus.
* LH peaks within 2 hours, then returns to basal levels within 8 hours.
* Further matings before the peak in LH will result in further LH release.
* After multiple matings over 4 hours or more, further matings will not result in any further LH release.
** Due to depletion of the pituitary pool of LH, or the pituitary becoming refractory to further GnRH stimulation.
* Once significant quantities of LH are reached, all ripe follicles will rupture (all or nothing response).
* Occasionally, ovulation will occur in the absence of contact with an entire tom.
** Receptors similar to those in the vulva are found in the lumbar area.
** These can be stimulated if the queen is mounted by other females or castrated cats.

=== Pseudopregnancy ===

* Sterile matings induce ovulation and result in pseudopregnancy.
* Progesterone concentrations are similar to those of pregnancy for the first 3 weeks.
* After this, progesterone levels gradually fall and reach baseline at 7 weeks.
* Oestrus will occur shortly afterwards.
* Nesting behaviour and lactation are rarely seen, but hyperaemia of the nipples is as evident as in pregnancy.
* Appetite may increase, and fat may distribute to create an increased abdominal size.

= Links =

* [[Oestrous Cycle Pharmacological Manipulation - Anatomy & Physiology|Pharmacological Manipulation of Oestrous Cycles]]
* [[Oestrus Behaviour - Anatomy & Physiology| Oestrus Behaviour and Methods of Oestrus Detection]]

[[Category:Female Reproduction]]

Infectious Agents - Overview

2011-01-14T15:06:04Z

Ge8680:

==Introduction==
Infectious agents are microorganisms found in nature that are harmful to animals and plants. Most microorganisms found in nature are not harmful, however some microorganisms can cause disease and are therefore referred to as pathogenic.
 
 
Microorganisms are categorised into distinct types. The main categories of veterinary interest are bacteria, fungi, protozoa, viruses and prions, although other microorganisms also exist such as algae.
 

==[[Bacteria]]==

Bacteria are unicellular prokaryotes, usually with rigid cell walls. They are much smaller than eukaryotic cells, although they can
easily be viewed with traditional light microscopy.
 
They have various shapes or morphologies such as rods, cocci, helical and branching and motile bacteria possess flagella. Bacteria contain a single circular chromosome containing DNA and reproduce by a process called binary fission which is an asexual process. Some bacteria also contain small extra-chromosomal DNA, referred to as plasmids, which have genes that are able to confer specific properties to bacteria such as antibiotic resistance.
 

There are two main groups (or domains) of bacteria; Archaebacteria and Eubacteria. Only Eubacteria are pathogenic in domestic
species.
 

==[[Fungi]]==

Fungi are non-photosynthesising eukaryotes including
yeasts, moulds and mushrooms which are either unicellular or multi-cellular. Moulds and mushrooms are multi-cellular and
produce filamentous microscopic structures whilst yeasts are unicellular and
have a spherical or ovoid shape. Unicellular fungi multiply by budding.
 

Cells found in moulds are cylindrical and attached end to
end forming branched structures called hyphae.
 

Some types of fungi are classed as pathogenic due to their ability
to secrete mycotoxins that are able to cause disease.
 

==[[Viruses]]==
The most notable difference between bacteria, fungi and
viruses is that viruses are not cells. Viruses consist of nucleic acid, either
DNA or RNA which is enclosed in a protective protein coat called a capsid.
Viruses have various shapes ranging from spherical to elongated.
 

As viruses are not cells, they do not possess the ability to
undertake metabolism and independant reproduction. Therefore viruses can only multiply
within living cells by making use of the cells own structures and enzymes.
Prokaryotic and eukaryotic cells are susceptible to infection by viruses.
 
Viruses are very small and not visible under light
microscopy. Scanning electron microscopes using a magnification of 100,000x are
used to demonstrate viruses in clinical specimens.

[[Category:Infectious Agents]]

Strongylus vulgaris

2010-01-15T20:18:17Z

Ge8680:

{{unfinished}}

{{toplink
|backcolour =
|linkpage =Parasites
|linktext =PARASITES
|pagetype=Bugs
|sublink1=Strongyloidea
|subtext1=STRONGYLOIDEA
}}
 

''Strongylus vulgaris'' is a parasite of horses.

==Appearance==
*Dark red
*Well developed buccal capsule in male

==Life cycle==
*Eggs shed in faeces onto pasture
*Develop into L3 larvae
*Ingested by horse
*Penetrate intestine mucosa
*Moult in 7 days to L4 in sub-mucosa
*L4 migrate to cranial mesenteric artery
*Develop over months
*Moult to L5
*Migrate to caecum and colon
*Form nodules around the larvae
*Nodules rupture into the lumen of the intestine
*Adults live in the caecum and colon

==Pathogenesis==
By larvae:
*Disruption to endothelium of blood vessel
* May cause [[Intestines Vascular Disturbances - Patholgoy#Arterial thromboembolism |arterial thromboembolism]] in the horse.
*May cause intestinal infarcts, see [[Thrombosis - Pathology#Intestinal Infarcts|General Pathology]]
By adults:
*Accidental damage to blood vessels as a result of feeding on intestinal mucosa

Strongyloidea

2010-01-15T19:09:56Z

Ge8680: /* General Appearance */

{{unfinished}}

{{toplink
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|linkpage =Parasites
|linktext =PARASITES
|pagetype=Bugs
|sublink1=Nematodes
|subtext1=NEMATODES
}}
 

== General Appearance ==
[[Image:Strongyloides stercoralis 2.jpg|thumb|right|150px|''Strongyloides stercoralis'' - Courtesy of the Laboratory of Parasitology, University of Pennsylvania School of Veterinary Medicine]]
[[Image:Strongyloides stercoralis.jpg|thumb|right|150px|''Strongyloides stercoralis'' - Joaquim Castellà Veterinary Parasitology Universitat Autònoma de Barcelona]]
[[Image:Strongyloides larvae.jpg|thumb|right|150px|''Strongyloides'' larvae - Joaquim Castellà Veterinary Parasitology Universitat Autònoma de Barcelona]]
[[Image:Strongyloides.jpg|thumb|right|150px|''Strongyloides'' - Joaquim Castellà Veterinary Parasitology Universitat Autònoma de Barcelona]]
*Bursate
*Large buccal capsule
*Relatively short (typically 1-5cm) but stout
*Heads often have characteristic features - teeth or cutting plates

== General Life-Cycle ==
*Like that of the trichostrongyloids (eggs are also 'typical strongyle eggs'), but:
**L3 → L4 → adult (typically occurs in the large intestine)
**Larvae penetrate the mucosal wall and elicit nodule formation
**Larvae of some species migrate around the body
**Prepatent period varies between species from 3 weeks to over 6 months

[[Strongylus vulgaris]]

[[Peritoneal Cavity Inflammatory - Pathology#In sheep|Peritonitis in sheep]] by penetration of intestines by larvae of ''Oesophagostomum columbianum''

''Strongylus edentatus'' and ''Strongylus equinus'' migrate through [[Peritoneal Cavity Parasitic - Pathology]]

''Stephanuris dentatus'' causes peritonitis in pigs [[Peritoneal Cavity Parasitic - Pathology]] and may cause cysts in the [[Pancreas Parasitic - Pathology|pancreas]]

''Syngamus laryngeus'' in [[Respiratory Parasitic Infections - Pathology#Syngamus laryngeus|larynx]] of cattle

Fleas

2010-01-12T14:35:13Z

Ge8680: /* Ctenocephalides felis */

{{review}}

{{toplink
|backcolour =
|linkpage =Insecta
|linktext =INSECTA
|pagetype=Bugs
|sublink1=Parasites
|subtext1=PARASITES
}}
 
[[Image: flea.jpg|thumb|right|250px|Robert Hooke's famous flea from Micrographia]]
==Siphonaptera Introduction==
[[Image:Arthropod classifiation.jpg|thumb|right|150px|Arthropod Classification - copyright nabrown RVC]]
Fleas are wingless insects that are laterally flattened so can move rapidly through hair and fur. Their hind legs are adapted for jumping. They are of major significance to veterinary practice and are seen on a daily basis at most general practices.

Adult fleas are blood sucking ectoparasites which can cause pruritis, annoyance, loss of condition and anaemia if present in large numbers. [[Skin Immunologic - Pathology#Flea bite hypersensitivity|Flea allergic dermatitis]] can also occur where the animal becomes allergic to the antigens in the flea saliva triggering a hypersensitivity reaction when the flea bites.

Fleas can also act as intermediate hosts for the tapeworm [[Dipylidium|''Dipylidium'']] and as an important vector for diseases such as cat scratch disease, the bubonic plague and [[Myxomatosis|myxomatosis]].

The terms '''ctenidia''' and '''combs''' can be used interchangably for spines on the head/thorax. Spines on the cheeks are referred to as '''genal''' and spines on the thorax are called '''pronotal''' combs. The presence and location of the chitinous spines are important in differentiating between the different flea species. The chitinous anal struts are also used for identification and help the flea larvae with vigorous motility.

==Species of veterinary importance==

===''Ctenocephalides felis''===
[[Image:Cat flea.jpg|thumb|right|150px|Cat Flea - Andy Brookes BS - Wikimedia Commons]]
*Most common flea on both cats and dogs

*Most important flea in veterinary medicine

*Commonly called the 'cat flea'

*Can bite humans and other animals

*Both genal and pronotal commbs present

*Similar length genal combs

*The first genal spine is 0.75 times the length of the second

*Sloping nose

*6 notches bearing setae on the dorsal border of the hind tibia

===''Ctenocephalides canis''===

*Less common

*Commonly called the 'dog flea'

*Host specific

*Both genal and pronotal commbs present

*Irregular length genal spines

*The first genal spine is 0.5 times the length of the second

*Rounded nose

===''Ceratophyllus gallinae''===

*Commonly called the 'poultry flea'

*Bites humans and other animals

*Pronotal combs only

===''Pulex irritans''===

*Commonly called the 'human flea'

*No combs

*Head rounded anteriorly

===''Spilopsyllus cuniculi''===

*Commonly called the 'rabbit flea'

*Both genal and pronotal combs present

*Genal comb obviously oblique

*Behaviour synchronised with the reproductive cycle of the rabbit
**Adults spend most of their time off the host taking occasional blood feeds
**Shortly before the doe gives birth the adult fleas attach to the ears of the rabbit and feed producing lots of faeces
**After parturition the adult fleas move onto the kittens where they feed, mate and lay eggs
**The new adult fleas emerge from the pupa before the kittens leave the nest

===Other important flea species===

*Fleas of wildlife can sometimes infect domestic animals

*Other species of importance are found in America
**E.g. ''Tunga penetrans'' or 'Jiggers' which burrow into the skin of man (also called the 'sand flea' or 'chigoe flea')

*''Nosopsyllus fasciatus''
**Affects rodents
**18-20 spines in pronotal ctenidium

*''Echisnophaga gallinacea''
**Affects poultry
**Frons (forehead) angled anteriorly
**Also called the 'sticktight' flea

*''Archaeopsylla erinacei''
**Affects hedgehogs
**1-3 short spines on genal ctendium
**1 short spine on pronotal ctenidium

==Life-cycle==
[[Image:Flea larvae.jpg|thumb|right|150px|Flea Larvae - Wikimedia Commons]]
A thorough understanding of the flea life-cycle is important in order to be able to advise owners of adequate treatments to control flea infections on their animals and within the home environment.

*The time for the egg to develop into the adult flea takes '''3-4 weeks''' in summer

*Duration of the life cycle is dependent on environmental temperature

'''1. Adults'''

*Uses changes in light intensity, warmth and carbon dioxide to locate host

*Once on host, the flea will usually remain
**With animals in close contact there may be a small degree of transfer between hosts
**The majority of adult fleas are acquired from the '''environment'''

*The adult flea takes frequent blood meals. 97% of fleas will feed within 1 hour of finding a host and feed for about 10-25 minutes.

*'''Flea dirt''' (faeces) are produced in large quantities

*The life span of the flea is determined by the grooming activity of the host
**Usually the adult flea lives for between '''7 and 10 days'''

'''2. Eggs'''

*The adult lays eggs 1-2 days after locating a host

*Approximately '''15 eggs''' are layed in the coat per day

*Eggs are ivory white, oval and approxiamtely 0.5mm long

*The eggs drop to the ground within hours
**In reality this usually happens when the animal jumps of the sofa or makes sudden movements. Flea eggs will therefore cluster in these '''hot spots''' around the house. These areas should be paid particular attention when treating the environment in the case of a flea infestation.

'''3. Larvae'''

*Larvae are small, about 2-5mm in length

*Larvae are yellow/white (look like maggots) and are covered in bristles

*They have chitinous mouthparts and anal struts which can be used for identification

*Larvae are negatively phototropic so try to move away from light sources
**E.g. under furniture, into thick mats or carpet

*Larvae feed on skin debris from other animals, flea dirt and other organic debris

*High humidity is needed for survival

*Freezing temperatures will kill larvae

'''4. Pupae'''

*The larvae pupate forming pupae of 5mm in length

*A silken cocoon surrounds the pupae
**Slightly sticky so small particles adhere to it
**These quickly become camouflaged in the environment

*Methoprene, the juvenile development hormone coordinates the growth of the immature stages
**Activates genetic switches
**Determines the sequence of tissue and organ development

*Newly developed adults do not leave the cocoon straight away
**The '''pupal window''' is the time that it takes for the adult to emerge
**Temperature determines when the adult fleas emerge
**Some fleas may wait several months before emerging

*Newly emerged unfed adults can survive days without feeding but once they have fed, if they fall off the host they can only survive hours

==Habitats==

*Only approximately '''5%''' of the flea population will be on the animal at any one time (and usually it is a much smaller percentage)

*The rest of the population are in the '''environment'''
**E.g. Eggs, larvae, pupae and unfed adults

*Fleas accumulate in certain '''hot spots''' where the animal spends the majority of its time
**E.g. Warm, shady, humid ares
**E.g. Outdoors in warmer climates or inside in temperate climates

*Very large numbers of eggs are found in areas where cats land after jumping as they have been dislodged
**E.g. Beside sofas

==Control==
[[Image:Flea Dirt.jpg|thumb|right|150px|Flea Dirt - Wikimedia Commons]]
[[Image:Flea Bites.jpg|right|Thumb|150px|Flea bites on a human - Wikimedia Commons]]
*Single or occasional treatments will only give temporary relief from fleas as the majority of the population is '''in the environment'''

*Appropriate action must be taken to stop re-infestation

*The animal must be rid of its resident flea population

*The animal should be protected against subsequent re-infestation
**From within the home
**From outside the home

*The environmental reservoir population should be eliminated
**Animal treatment to deplete reservoir
***Adulticides
***Adulticides with larvicidal effects
***Insect growth regulators (IGR's)
**Direct chemical treatment of domestic environment
***Insecticides
***Insect growth regulators
***Inorganic chemicals
***Entomophagous nematodes (These are parasitic nematodes which predate other parasite eggs)

*To prevent resistance occurring, control methods should not rely solely on chemical methods
**Hygiene such as regular vacuuming and washing of the animal's bedding should also occur for the most effective treatment

*For more information on the chemicals used for flea treatment click [[Ectoparasiticides|here]]

==[[Insecta Flashcards - WikiBugs#Fleas|Fleas Flashcards]]==

==Links==
''Internal''
*[[Skin Immunologic - Pathology#Flea bite hypersensitivity|Flea allergic dermatitis (FAD)]]

*Fleas act as intermediate hosts for [[Dipylidium|'''''Dipylidium'' tapeworms''']]

*Fleas act as vectors for [[Poxviruses#Myxoma virus|myxomatosis]] in rabbits

''External''
*[http://en.wikipedia.org/wiki/Flea Wikipedia- Fleas]

Cyclophyllidea

2010-01-11T17:49:31Z

Ge8680: /* Introduction */

{{toplink
|backcolour =
|linkpage =Parasites
|linktext =PARASITES
|pagetype=Bugs
|sublink1=Cestodes
|subtext1=CESTODES
}}
 
[[Image:Dipylidium caninum 2.jpg|right|150px|thumb|''Dipylidium caninum'' - Courtesy of the Laboratory of Parasitology, University of Pennsylvania School of Veterinary Medicine]]
[[Taeniidae]]

[[Dipylidium]]

[[Davainea]]

[[Anoplocephalidae]]

== Introduction ==
*Cyclophyllidean tapeworms have four circular suckers around the scolex (head). Some species also have hooks on the suckers, and these species are said to be ‘armed’. They also consist of a short unsegmented neck and a chain of segments.

*Most cyclophyllidean species live in the small intestine. New segments bud off from behind the scolex. These do not have an alimentary tract, but absorb nutrients across the body surface. This is covered by a tegument which is like that as for trematodes, but has a microthrix (minute finger-like projections) to increase surface area. Below the tegument are muscle cells and the parenchyma – a syncitium of cells, which fills the space between the organs. The nervous system consists of ganglia in the scolex, from which nerves enter the strobila. The excretory system is composed of flame cells leading to efferent canals, which run through the strobila to discharge at the terminal segment.
[[Image:Taenia proglottid.jpg|thumb|right|150px|Taenia proglottid - Courtesy of the Laboratory of Parasitology, University of Pennsylvania School of Veterinary Medicine]]
*Each segment develops male and female organs, but they usually cross-fertilise. The genital pores are lateral. The proglottids become sexually mature as they pass down the strobila. As the segment matures, its internal structure largely disappears and the gravid proglottid eventually only contains remnants of the branched uterus packed with eggs. The ‘gravid’ (that is to say, pregnant) segments at the end of the chain may contain greater than 100,000 eggs. In general, one or two segments drop off daily to exit the animal by their own mobility or to be swept out with the faeces. The gravid segments are shed intact from the strobila.

*Outside the body, the eggs are freed by disintegration of the segment, or are shed through the genital pore. Each egg is immediately infective and contains a tapeworm larva with six hooks (the oncosphere), surrounded by a thick, dark ‘shell’ made of numerous blocks (giving a striated appearance when viewed under the microscope). A true shell, which is a delicate membrane, is often lost while still in the uterus.

== Life-Cycle ==
Indirect with one or more intermediate hosts. When the egg is ingested by the intermediate host, the gastric and intestinal secretions digest the thick shell and activate the 6-hooked oncosphere. Using its hooks, it tears through the mucosa of the host to reach the blood or lymph system, or in the case of invertebrates, the body cavity. Once it has reached its predilection site, the oncosphere loses its hooks and develops, depending on the species, into one of the following larval stages, known as a metacestode. There are six types of metacestode (in increasing order of complexity:

1) '''Cysticercus''': a fluid-filled bladder with one inverted scolex

2) '''Cysticercoid''': pinhead size; only found in invertebrates; like the cysticercus, but the bladder is reduced to a potential space and the scolex is not inverted

3) '''Strobilocercus''': restricted to the cat tapeworm Taenia taeniaeformis; like a cysticercus, but the single scolex is attached to the bladder by a chain of segments

4) '''Coenurus''': like a cysticercus, but has multiple inverted scolices

5) '''Hydatid cyst''': the metacestode of Echinococcus granulosus; this fluid-filled bladder can grow to the size of a football; it is lined with germinal epithelium that buds off brood capsules internally; inverted scolices form inside these; hydatid sand is the name given to the brood capsules and scolices in the hydatid fluid; the host attempts to wall off the hydatid cyst with fibrous tissue; between this and the germinal membrane is an amorphous layer

6) '''Alveolar cyst''': the metacestode of Echinococcus multilocularis; this is like the hydatid cyst, but daughter cysts bud off the external, as well as the internal, surface of the germinal layer, with the result that the metacestode expands by infiltrating through the tissue, rather like a tumour.

When the metacestode is ingested by the final host, the scolex attaches to the mucosa, the remainder of the structure is digested, and a chain of proglottids (segments) begins to grow from the base of the scolex.

Infection of the final-host involves at least three epidemiological relationships:

1) '''predator-prey''', e.g. cat eating infected mouse

2) '''accidental''', e.g. horse eating infected pasture mites

3) '''irritation''', e.g. infected flea on animal = exaggerated grooming of animal = swallowed

Seasonality of Reproduction - Anatomy & Physiology

2010-01-07T19:24:27Z

Ge8680: /* Long day breeders */

{{review}}

{{toplink
|backcolour =EED2EE
|linkpage =Reproductive System - Anatomy & Physiology
|linktext =Reproductive System
|maplink = Reproductive System (Content Map) - Anatomy & Physiology
|pagetype =Anatomy
|sublink1=Reproductive System - Anatomy & Physiology#Female Reproductive Tract
|subtext1=FEMALE REPRODUCTIVE TRACT
}}
 

==Introduction==
Unlike polyoestrus animals such as the cow or sow which can reproduce all year round some species such as the mare, ewe, goat, rabbit, hamster and doe have an '''anoestrus''' phase to their reproductive cycling. This means that for part of the year they are not experiencing oestrous cyclicity and so are not reproductively active. Such animals can be long or short day polyoestrus breeders. Seasonality of reproduction is due to the effect of light levels on the brain. Reproductive seasonality maximises the chance of offspring survival by timing parturition to coincide with spring when nutritional and climate conditions are optimum for lactation and for growth of the offspring. It is important to be able to distinguish between seasonal anoestrus and pathological infertility. Both males and females exhibit reproductive seasonality. However, the female is more strongly influenced by season.

==Mechanism of seasonality==
During the day lights levels are detected by the [[Eye - Anatomy & Physiology#Optics|retina]] which sends impulses to the [[Hypothalamus_-_Anatomy_%26_Physiology#Nuclei|suprachiasmatic nucleus]] of the [[Hypothalamus_-_Anatomy_%26_Physiology|hypothalamus]] and then to the superior cervical ganglion. Postganglionic nerve fibres synapse with inhibitory nerve fibres within the pineal gland. These fibres cause inhibition of the pinealocyte cells of the [[Pineal_Gland_-_Anatomy_%26_Physiology|pineal gland]] preventing synthesis of the hormone [[Endocrine System - Melatonin - Anatomy & Physiology|melatonin]]. At night there is reduced retinal firing and so reduced inhibition of pinealocytes by postganglionic superior cervical gangion fibres and so melatonin is synthesised and released. Melatonin stimulates the synthesis and release of GnRH from the hypothalamus leading to pulses of luteinising hormone release from the [[Pituitary_Gland_-_Anatomy_%26_Physiology|pituitary gland]]. High frequency, low amplitude LH pulses lead to breeding activity. Where as low frequency, high amplitude LH pulses lead to anoestrus and inactive gonads.

==Long day breeders==
*Hamsters
*The mare
*The mares breeding period is from April-June, these months having increasingly long hours of daylight.
*Reproductive cycling occurs with increased photoperiod (increasing light levels).

==Short day breeders==
*Ewe, Doe, Goat
*Their breeding season is at the end of summer and beginning of autumn.
*Respond to decreased photoperiod.

==Manipulation of Seasonal breeders==
Apart from [[Oestrous_Cycle_-Pharmacological_Manipulation_of_Oestrous_Cycles_-_Anatomy_%26_Physiology|pharmalogical manipulation]] of the oestrous cycle, photoperiod, nutrition and temperature may also play a part in the controlling entry into the breeding season in some species.

===Reasons for controlling breeding seasons===
'''The Mare'''
*To shorten the Anoestrus period after foaling.
*In order to synchronize a group of mares so that they may all be mated at the same time or to make [[Reproductive_Technologies_-Multiple_Ovulation_and_Embryo_Transfer-_Anatomy_%26_Physiology|Embryo Transfer]] possible.
*Control of entry into the breeding season is particually important in producing foals for the racing industry. Racehorses run from the age of two years old, with the age of the horse being measured from the 1st of January. Producing horses born as close to the 1st of January as possible gives them a performance advantage when racing.

'''The Ewe'''
*In order to produce lambs for the easter markets ewes have to be mated earlier in the year.

===Photoperiod control===
In the mare exposure to 16 hours light/day from mid november can bring the first ovulation of the breeding season forward from early april to early february, advancing pregnancy by up to two months.

File:Suffolk Ram.JPG

2009-12-31T14:55:49Z

Ge8680: 7 month old Suffolk ram

7 month old Suffolk ram

Bovine Breeds - WikiNormals

2009-12-31T14:00:08Z

Ge8680:

{{toplink
|linkpage =WikiNormals
|linktext =WikiNormals
|maplink = WikiNormals Content Map
|pagetype =WikiNormals
|sublink1= Bovine Section - WikiNormals
|subtext1= Bovine Section
}}
 

===Overview===

The following breeds have been classified according to The Cattle Site, an international database for cattle breeds. Clearly far more breeds exist than have been included below although these are not likely to be encountered in Europe. For further information regarding a specific breed please see http://thecattlesite.com/breeds/.

==Dairy Breeds==
 

===UK Breeds===
<gallery widths="115px" perrow="6">
Image:ayrshire.jpg| '''Ayrshire''' WikiCommons
Image:Brown Swiss Breed.png|'''Brown Swiss'''© Nottingham Uni 2009
Image:Shorthorn.jpg|'''Dairy Shorthorn''' WikiCommons
Image:Milking_devon.jpg|'''Devon (Milking)''' WikiCommons
Image:Friesian_cow.JPG|'''Friesian''' WikiCommons
Image:Guernsey.jpg|'''Guernsey''' WikiCommons
Image:Holstein.JPG|'''Holstein''' © Nottingham Uni 2009
Image:Irish_moiled.jpg|'''Irish Moiled''' WikiCommons
Image:Jersey.jpg|'''Jersey''' WikiCommons
Image:Kerry.jpeg|'''Kerry''' WikiCommons
<--Add more breeds here-->

</gallery>

===Continental Breeds===
<gallery widths="115px" perrow="6">

Image:Busa.jpg|'''Busa''' thecattlesite.com
Image:Canadienne.jpg|'''Canadienne''' WikiCommons
Image:Dutch_belted.jpg|'''Dutch Belted''' WikiCommons
Image:Estonianred.jpg|'''Estonian Red''' ansi.okstate.edu
Image:Girolando.jpg|'''Girolando''' WikiCommons
Image:Illawarra.jpg|'''Illawarra''' ansi.okstate.edu
Image:Lineback.jpg|'''Lineback''' WikiCommons
Image:Meuse_Rhine_Issel.jpg|'''Meuse Rhine Issel''' rakaunuifarm.com
Image:Montbéliarde.jpg|'''Montbéliarde''' WikiCommons
Image:Normande.jpg|'''Normande''' WikiCommons
Image:Norwegian_Red.JPG|'''Norwegian Red''' WikiCommons
Image:Randall.jpg|'''Randall''' WikiCommons
Image:Sahiwal.JPG|'''Sahiwal''' kanglade.com
</gallery>

==Beef Breeds==
===UK Breeds===
<gallery widths="115px" perrow="6">
Image:Angus.jpg|'''Aberdeen Angus''' WikiCommons
Image:Beef_shorthorn.jpg|'''Beef Shorthorn''' WikiCommons
Image:Belted_galloway.jpg|'''Belted Galloway''' WikiCommons
Image:British_white.jpg|'''British White''' WikiCommons
Image:Red_Devon.jpg|'''Devon''' WikiCommons
Image:Dexter.jpg|'''Dexter''' WikiCommons
Image:Longhorn.jpg|'''English Longhorn''' WikiCommons
Image:Galloway.JPG|'''Galloway''' WikiCommons
Image:Gloucester.jpg|'''Gloucester''' thecattlesite.com
Image:Hereford_bull.jpg|'''Hereford''' WikiCommons
Image:Highland_cattle.jpg|'''Highland''' WikiCommons
Image:Luing.jpg|'''Luing''' WikiCommons
Image:Red-angus.jpg|'''Red Angus''' ''(And Black)'' WikiCommons
Image:Red_Poll.jpg|'''Red Poll''' WikiCommons
Image:Shetland_cattle.JPG|'''Shetland''' WikiCommons
Image:South_devon.jpg|'''South Devon''' WikiCommons
Image:Sussex_cattle.jpg|'''Sussex''' thecattlesite.com
Image:Welsh_black.jpg|'''Welsh Black''' WikiCommons
Image:Whitebred.jpg|'''Whitebred Shorthorn''' thecattlesite.com
<--Add more breeds here-->

</gallery>

===Continental Breeds: Europe/Asia/Africa/Americas/Australia===
<gallery widths="115px" perrow="6">
Image:Africander.jpg|'''Africander/Afrikaner (Southern Africa)''' ansi.okstate.edu
Image:Aubrac.jpg|'''Aubrac''' WikiCommons
Image:Barzona.jpg|'''Barzona''' ansi.okstate.edu
Image:Bazadaise.jpg|'''Bazadaise''' WikiCommons
Image:Beefalo.jpg|'''Beefalo''' thecattlesite.com
Image:Beefmaster.jpg|'''Beefmaster''' thecattlesite.com
Image:Belgian_blue.jpg|'''Belgian Blue''' WikiCommons
Image:Belmont_Red.jpg|'''Belmont Red''' WikiCommons
Image:Blonde.jpg|'''Blonde d'Aguitaine''' thecattlesite.com
Image:Bonsmara.jpg|'''Bonsmara (Southern Africa)''' thecattlesite.com
Image:Boran.jpg|'''Boran''' thecattlesite.com
Image:Braford.jpg|'''Braford''' WikiCommons
Image:Brahman.jpg|'''Brahman''' WikiCommons
Image:Brahmousin.jpg|'''Brahmousin''' thecattlesite.com
Image:Brangus.JPG|'''Brangus''' WikiCommons
Image:Buelingo.jpg|'''Buelingo''' thecattlesite.com
Image:Canchim.jpg|'''Canchim''' WikiCommons
Image:Caracu.jpg|'''Caracu''' thecattlesite.com
Image:Charolais.jpg|'''Charolais''' WikiCommons
Image:Chianina.jpg|'''Chianina''' WikiCommons
Image:Corriente.jpg|'''Corriente''' WikiCommons
Image:Drak.jpg|'''Drakensberger (Southern Africa)''' thecattlesite.com
Image:Droughtmaster.jpg|'''Droughtmaster''' WikiCommons
Image:Gelbvieh.jpg|'''Gelbvien''' WikiCommons
Image:Limousin.gif|'''Limousin''' WikiCommons
Image:Lincolnred.jpg|'''Lincoln Red''' WikiCommons
Image:Lowline.jpg|'''Lowline''' WikiCommons
Image:maineanjou.jpg|'''Maine Anjou''' WikiCommons
Image:Marchigiana.jpg|'''Marchigiana''' thecattlesite.com
Image:Minhereford.jpg|'''Miniature Hereford''' WikiCommons
Image:Mirandesa.jpg|'''Mirandesa''' thecattlesite.com
Image:Murray_Grey.JPG|'''Murray Grey''' Wikicommons
Image:Nelore.jpg|'''Nelore''' Wikicommons
Image:Nguni.jpg|'''Nguni (Africa)''' thecattlesite.com
Image:Parthenais.jpg|'''Parthenais''' bovin.qc.ca
Image:Piemontese.jpg|'''Piemontese''' WikiCommons
Image:Pinzgauer.jpg|'''Pinzgauer''' pinzgauer.ca
Image:Retinta.jpg|'''Retinta''' Wikicommons
Image:Romagnola.jpg|'''Romagnola''' cattlenetwork.net
Image:Salers.jpg|'''Salers''' WikiCommons
Image:Sanganer.jpg|'''Sanganer''' thecattlesite.com
Image:Santa_cruz.jpg|'''Santa Cruz''' king-ranch.com
Image:Santa_Gertrudis.JPG|'''Santa Gertrudis''' WikiCommons
Image:Senepol.jpg|'''Senepol''' thecattlesite.com
Image:Simbrah.jpg|'''Simbrah''' thecattlesite.com
Image:Simmental.JPG|'''Simental''' WikiCommons
Image:Speckle_Park.jpg|'''Speckle Park''' thecattlesite.com
Image:Tarentaise.jpg|'''Tarentaise''' WikiCommons
Image:Texas_Longhorn.jpg|'''Texas Longhorn''' WikiCommons
Image:Tuli.jpg|'''Tuli''' WikiCommons
Image:Wagyu.jpg|'''Wagyu''' WikiCommons
Image:Watusi.jpg|'''Watusi''' WikiCommons
Image:Zebu.jpg|'''Zebu''' WikiCommons
<--Add more breeds here-->

</gallery>