WikiVet English - User contributions [en]

Anaesthesia

2009-04-09T18:51:33Z

Alsiola:

{{unfinished}}

*[[Principles of Anaesthesia]].
*Principles Of Analgesia
**[[Pain|Pain Pathways]]
**Systemic Analgesia
**Local Analgesia
***Local Infiltration
***Epidural
***Paravertebral
***Nerve Blocks
***Intravenous Regional Anaesthesia
*Fluid Therapy
**Principles of Fluid Therapy
**Crystalloids
**Colloids
*[[Anaesthetic Equipment]]
**[[Anaesthetic Machines]]
**[[Vaporisers]]
**[[Breathing Systems]]
*[[Sedatives and Tranquilisers]]
*Anaesthetic Drugs
**Injectable Agents
***[[Phenothiazines]]
***[[Alpha-2 Agonists]]
***[[Opioids]]
***[[Benzodiazepines]]
***Barbiturates
***Dissociative Agents
***[[Steroids]]
**Inhalation Agents
***Halothane
***Enflurane
***Isoflurane
***Sevoflurane
***Desflurane
***Nitrous Oxide
**[[Local Anaesthetics]]
***[[Local Anaesthetics#Lidocaine|Lidocaine]]
***[[Local Anaesthetics#Mepivicaine|Mepivicaine]]
***[[Local Anaesthetics#Bupivicaine|Bupivicaine]]
**Neuromuscular Blockers
***Depolarising
***Non-depolarising
**Interventional Agents
***Dobutamine
***Dopamine
***Ephedrine
***Phenylephrine
***Vasopressin
*Inducing Anaesthesia
*[[Monitoring Anaesthesia]]
**[[Manual Techniques]]
**[[Blood Pressure]]
**[[Respiratory Gas Analysis]]
**[[Pulse Oximetry]]
**[[Temperature]]
**[[ECG]]
**[[Blood Gas Analysis]]
*Recovery From Anaesthesia
*Complications Of Anaesthesia
*Species Specific Considerations
**Feline
**Canine
**Equine
**Bovine
**Camelid
**Small Furry
**Fish
*Special Cases
**Cardiovascular
**Respiratory
**etc.
**Pregnancy

[[General Anaesthetics]]

Equine Respiratory Diseases

2009-04-07T00:09:04Z

Alsiola: /* Lungs */

{{horse}}

=Presenting Signs=
* [[Cough - Equine|Cough]]
* [[Nasal Discharge]]
* [[Tachypnoea]]
* [[Respiratory Noise]]
* [[Neonatal Respiratory Disease]]

=Disease Processes=
==The Nasal Cavity and Paranasal Sinuses==
* [[Infectious Sinusitis]]
* [[Neoplasia]]
* [[Ethmoid Haematoma]]
* [[Paranasal Sinus Cyst]]
* [[Epidermal Inclusion Cyst]]
==Pharynx and Larynx==
* [[Laryngeal Paralysis]]
* [[Dorsal Displacement Of The Soft Palate]]
* [[Pharyngeal Lymphoid Hyperplasia]]
==Guttural Pouches==
* [[Guttutal Pouch Empyema]]
* [[Guttural Pouch Tympany]]
* [[Guttural Pouch Mycosis]]
==Trachea==
* [[Tracheitis]]
* [[Collapsing Trachea]]
==Lungs==
* [[Inflammatory Airway Disease]]
* [[Pneumonia]]
* [[Pleuropneumonia]]
* [[Pleural Effusions]]
* [[Pulmonary Oedema]]
* [[Neoplasia]]
* [[Abscesses]]

Equine Respiratory Diseases

2009-04-07T00:07:57Z

Alsiola: restructure

{{horse}}

=Presenting Signs=
* [[Cough - Equine|Cough]]
* [[Nasal Discharge]]
* [[Tachypnoea]]
* [[Respiratory Noise]]
* [[Neonatal Respiratory Disease]]

=Disease Processes=
==The Nasal Cavity and Paranasal Sinuses==
* [[Infectious Sinusitis]]
* [[Neoplasia]]
* [[Ethmoid Haematoma]]
* [[Paranasal Sinus Cyst]]
* [[Epidermal Inclusion Cyst]]
==Pharynx and Larynx==
* [[Laryngeal Paralysis]]
* [[Dorsal Displacement Of The Soft Palate]]
* [[Pharyngeal Lymphoid Hyperplasia]]
==Guttural Pouches==
* [[Guttutal Pouch Empyema]]
* [[Guttural Pouch Tympany]]
* [[Guttural Pouch Mycosis]]
==Trachea==
* [[Tracheitis]]
* [[Collapsing Trachea]]
==Lungs==
* [[Pneumonia]]
* [[Pleuropneumonia]]
* [[Pleural Effusions]]
* [[Pulmonary Oedema]]
* [[Neoplasia]]
* [[Abscesses]]

Talk:Equine Respiratory Diseases

2009-04-06T23:58:26Z

Alsiola: New page: This is a somewhat confused page, containing clinical signs (e.g. The Coughing Horse), groups of diseases (e.g. Guttural Pouch Disease), and specific disease entities (e.g. Pulmonary Absce...

This is a somewhat confused page, containing clinical signs (e.g. The Coughing Horse), groups of diseases (e.g. Guttural Pouch Disease), and specific disease entities (e.g. Pulmonary Abscesses). I think a more structured approach is warranted, with a combination of the above. For example, there should be a page for "The Coughing Horse", which describes differential diagnoses, and outlines a potential work up. This should exist for each particular presenting sign. There should also be specific disease entities, linked to by the presenting sign pages, and potentially also listed here under categories. I don't really see the need for an actual page on groups of diseases by anatomic location, unless it is simply to list the potential disease processes. This function is better served by categories on the main page. I'm going to make some changes, so if anyone objects let me know why here! [[User:Alsiola|alsiola]] 23:58, 6 April 2009 (UTC)

Anaesthesia

2009-04-06T20:08:19Z

Alsiola:

{{unfinished}}

*Principles Of Anaesthesia
*Principles Of Analgesia
**Pain Pathways
**Systemic Analgesia
**Local Analgesia
***Local Infiltration
***Epidural
***Paravertebral
***Nerve Blocks
***Intravenous Regional Anaesthesia
*Fluid Therapy
**Principles of Fluid Therapy
**Crystalloids
**Colloids
*Anaesthetic Equipment
**Anaesthetic Machines
**Vaporisers
**Breathing Systems
*Anaesthetic Drugs
**Injectable Agents
***Phenothiazines
***Alpha-2 antagonists
***Opioids
***Benzodiazapenes
***Barbiturates
***Dissociative Agents
***Steroids
**Inhalation Agents
***Halothane
***Enflurane
***Isoflurane
***Sevoflurane
***Desflurane
***Nitrous Oxide
**Local Anaesthetics
***Lidocaine
***Mepivicaine
***Bupivicaine
**Neuromuscular Blockers
***Depolarising
***Non-depolarising
**Interventional Agents
***Dobutamine
***Dopamine
***Ephedrine
***Phenylephrine
***Vasopressin
*Inducing Anaesthesia
*Monitoring Anaesthesia
**Manual Techniques
**Blood Pressure
**Respiratory Gas Analysis
**Pulse Oximetry
**Temperature
**ECG
**Blood Gas Analysis
*Recovery From Anaesthesia
*Complications Of Anaesthesia
*Species Specific Considerations
**Feline
**Canine
**Equine
**Bovine
**Camelid
**Small Furry
**Fish
*Special Cases
**Cardiovascular
**Respiratory
**etc.
**Pregnancy

[[Sedatives and Tranquilisers]]

[[Local Anaethetics]]

[[General Anaesthetics]]

Corneal Ulcer - Horse

2009-04-06T20:05:19Z

Alsiola:

{{unfinished}}
{{dog}}{{cat}}{{horse}}

=Equine Corneal Ulcers=
==Introduction==
Corneal ulceration is a very common disease of the equine eye and can have sight threatening consequences. Aggressive treatment is always indicated, as even apparently mild ulcers can progress quickly, causing serious complications.

==Aetiology==
A distinct cause for initial ulceration is not commonly found, although in many cases it can be assumed to be traumatic in origin. The horse’s eye is especially vulnerable to trauma due to its prominent position, compared with other species. Exposure keratitis can occur in the horse, most commonly secondary to facial nerve paralysis. Hospitalised animals have been shown to have a decreased corneal reflex, and this corresponds to an increased incidence of ulcers in the hospitalised population. Foreign bodies embedded in the palpebral conjunctiva, or the nictitating membrane can cause persistent irritation and ulceration. Often the shape/distribution of the lesion is suggestive of this aetiology, but even in the absence of a characteristic lesion their presence should be considered and sought out.

Bacterial (+/- fungal) infection occurs readily after initial ulceration, as disruption of the corneal epithelium allows attachment and colonisation of the underlying tissues by normal corneal commensals. Commonly isolated bacteria include Staphylococcus spp., Streptococcus spp. and Pseudomonas spp., and empirical anti-microbial therapy should be effective against these bacteria.

==Clinical Signs==

* Ocular Pain
** Blepharospasm
** Increased lacrimation
** Photophobia
* Corneal Oedema (1⁰/2⁰)
* Scleral injection
* Conjunctivitis

==Diagnostics==
Differential diagnoses for the painful equine eye:

* Ulceration
* Uveitis
* Blepharitis
* Conjunctivitis
* Glaucoma
* Dachrocystitis

A full ocular exam should be performed on every painful eye you are presented with.

Fluoroscein staining is usually diagnostic for corneal ulcers, although staining with Rose Bengal is also recommended as it can pick up early viral/fungal lesions, which will appear as multifocal disturbances to the tear film.

Culture and sensitivity is recommended for rapidly progressive or deep corneal ulcers. Cotton swabbing is often inadequate, and corneal scraping, for example, with the blunt side of a scalpel blade is usually required. This can be greatly facilitated by the use of local nerve blocks and topical anaesthesia.

There is almost invariably a secondary uveitis present with corneal ulceration, and signs of this may also be seen: miosis, corneal oedema, aqueous flare, hypopyon, IOP changes.

==Treatment==
Medical therapy should be based upon the severity of disease initially, and then by the response to therapy – if it ain’t broke don’t fix it, but don’t flog the metaphorical dead horse! The aims of our initial therapy are:

* Antibiosis
* Analgesia
* Anti-inflammatory
* Mydriatic

The initial choice of antibiotic depends upon personal choice, experience and availability, but could include chloramphenicol, chlortetracycline, bacitracin-neomycin-polymyxin (BNP), ciprofloxacin, ofloxacin and tobramycin. Topical gentamicin formulations are also available, but in the opinion of some, should be reserved for cases with stromal melting. Frequency of application can vary from q1h to q8h, depending on both the severity of the lesion, and the formulation used (ointment vs. drops).

Much of the pain associated with corneal ulceration is due to the secondary uveitis and miosis, and effective relief can often be gained with topical atropine(1%), leading to mydriasis. Dosing is generally q4h initially, and then as required to maintain dilation. Mydriasis is also important to avoid some of the complications associated with uveitis, such as synechiae formation and glaucoma. Pain is also associated with inflammatory response occurring in the adjacent sclera and conjunctiva, and systemic analgesia in the form of NSAIDs is usually indicated, for example, flunixin meglumin 1.1mg/kg, BID. Topical NSAIDs are available (diclofenac, flurbiprofen) and effective, but have been shown to increase corneal healing time.

In horses that are difficult to treat, or in cases that require very frequent treatment, then placement of a sub-palpebral lavage system can be very useful. As an adjunct to therapy, physical protection of the eye may be required, in the form of a mask. Some horses will rub their eyes in response to pain, and this can cause further corneal damage. Box rest is also vital, as over-exertion has been linked to intra-ocular haemorrhage and increased severity of uveitis.

Success in your therapeutic regime can be judged by a reduction in pain, and a decrease in size of the ulcer. Healing generally occurs rapidly at first, followed by a slowing after 5-7 days. As a rough guide, a non-infected ulcer can be expected to heal at approximately 0.6mm/day.

==Complications==
===It’s not healing!===
*Is there a persistent source of irritation?
**Foreign body
**Self traumatisation
**Iatrogenic.
*Is it infected?
**Review antibiotic therapy
**C+S if not already performed.
*Immunosuppression?
**Cushing’s
**Steroid therapy.
*Compliance?
**Is what you’ve prescribed getting onto the eye!
*None of the above?
**Abnormal epithelium may have formed, keratectomy may be appropriate.

===It’s starting to melt!===

Melting ulcers reflect inappropriate collagenolysis of the corneal stroma, by matrix-metalloproteinases (MMPs). Bacterial pathogens (especially Pseudomonas and β-haemolytic Streptococcus) induce the corneal epithelial cells and resident leucocytes to upregulate pro-inflammatory, and MMP-activating cytokines (IL-1,-6 and -8). These bacteria can also produce their own proteinases. The combination of exogenous, and upregulated endogenous, proteinases leads to a rapid breakdown of collagen, with the characteristic melting appearance. Untreated this can lead to perforation within 12 hours (so act hard and fast!). There are several therapeutic options for inhibiting MMPs:

* Autogenous serum – administer topically as often as possible. Keep refrigerated and change every 8 days.
* EDTA - 0.05% q1h
* Acetylcysteine – 5-10% q1h
* Tetracyclines – Doxycycline especially has been shown to have anti-MMP effects
* Tetanus antitoxin – can be delivered sub-conjunctivally. Contains macroglobulins with anti-collagenase effects.

A combination of the above may be necessary early in the disease course. Effective antibiosis is also paramount, and gentamicin is a good empirical choice (although there are some reports of gentamicin-resistant Pseudomonas species). Obviously, treating an eye this frequently in practice will be difficult, so referral is probably the best option.

MMPs can be further activated iatrogenically, by treatment (topical or systemic) with corticosteroids. Steroids also reduce the immune defences of the eye, so just in case you forgot...

Don’t use steroids on corneal ulcers!!!

===It’s about to rupture/it just ruptured!===

The appearance of a descematocoele should alert you to the danger of the eye rupturing. Put a do-nut bandage over the eye, and give some broad spectrum antibiosis in case it ruptures on the way to the referral centre! Enrofloxacin is probably a good choice as it has good ocular penetration.

Corneal Ulcer - Horse

2009-04-06T20:04:06Z

Alsiola:

User:Alsiola

2009-04-06T19:37:29Z

Alsiola: New page: Well hello. My name is Alex, I'm a final year student at Liverpool. Logged on here to write a few articles as a revision process. My main interests are anything equine, eyes or anaesthes...

Well hello. My name is Alex, I'm a final year student at Liverpool. Logged on here to write a few articles as a revision process. My main interests are anything equine, eyes or anaesthesia. Anyone wants a hand on any pages, then let me know.

Talk:Anaesthesia

2009-04-06T19:35:48Z

Alsiola: New page: I have taken the liberty of creating a framework for the Anaesthesia section, which was sadly lacking. If anyone sees any omissions, or frivolous additions, then please edit away. Likewi...

I have taken the liberty of creating a framework for the Anaesthesia section, which was sadly lacking. If anyone sees any omissions, or frivolous additions, then please edit away. Likewise if you think a totally different structure is more appropriate, then go for it. I'm going to start working through some articles (it'd good revision!), please come and help me![[User:Alsiola|Alsiola]] 19:35, 6 April 2009 (UTC)

Anaesthesia

2009-04-06T19:33:51Z

Alsiola:

{{unfinished}}

*Principles Of Anaesthesia
*Principles Of Analgesia
**Pain Pathways
**Systemic Analgesia
**Local Analgesia
***Local Infiltration
***Epidural
***Paravertebral
***Nerve Blocks
***Intravenous Regional Anaesthesia
*Fluid Therapy
**Principles of Fluid Therapy
**Crystalloids
**Colloids
*Anaesthetic Equipment
**Anaesthetic Machines
**Vaporisers
**Breathing Systems
*Anaesthetic Drugs
**Injectable Agents
***Phenothiazines
***Alpha-2 antagonists
***Opioids
***Benzodiazapenes
***etc.
**Inhalation Agents
***Halothane
***Enflurane
***Isoflurane
***Sevoflurane
***Desflurane
***Nitrous Oxide
**Local Anaesthetics
***Lidocaine
***Mepivicaine
***Bupivicaine
**Neuromuscular Blockers
***Depolarising
***Non-depolarising
**Interventional Agents
***Dobutamine
***Dopamine
***Ephedrine
***Phenylephrine
***Vasopressin
*Inducing Anaesthesia
*Monitoring Anaesthesia
**Manual Techniques
**Blood Pressure
**Respiratory Gas Analysis
**Pulse Oximetry
**Temperature
**ECG
**Blood Gas Analysis
*Recovery From Anaesthesia
*Complications Of Anaesthesia
*Species Specific Considerations
**Feline
**Canine
**Equine
**Bovine
**Camelid
**Small Furry
**Fish
*Special Cases
**Cardiovascular
**Respiratory
**etc.
**Pregnancy

[[Sedatives and Tranquilisers]]

[[Local Anaethetics]]

[[General Anaesthetics]]

Colic

2009-04-06T19:14:26Z

Alsiola: /* Post-operative Survival */

{{unfinished}}
{{horse}}

'''Colic in [[horse]]s''' is defined as [[abdominal pain]], and can be caused by a wide variety of conditions. Many of these conditions are life threatening, and therefore it is essential to diagnose and treat cases of colic as quickly as possible. The most common causes of colic are [[Gastrointestinal tract|gastrointestinal]] conditions, although it can also be caused by other abdominal conditions. In the latter case, it is often called false colic. Treatment of colic is largely dependent upon identifying the underlying reason for the pain, and treating this cause appropriately. Most commonly this is done [[medicine|medically]], but in a small percentage of cases, [[surgery|surgical intervention]] is needed. Among [[domesticated]] horses, colic is a major cause of premature death. The incidence of colic in the general horse population has been estimated between 10 and 20 percent on an annual basis. It is important that any person who owns or works with horses be able to recognize the signs of colic, so that a [[veterinarian]] may be called promptly.

==Pathophysiology==
This can be divided broadly into simple obstructions, strangulating obstructions, and non-strangulating [[infarctions]].

===Simple Obstruction===
This is characterised by a physical obstruction of the intestine, which can be due to impacted food material, [[stricture]] formation, or foreign bodies. The primary pathophysiological abnormality caused by this obstruction is related to the trapping of fluid within the intestine oral to the obstruction. This is due to the large amount of fluid produced in the upper gastro-intestinal tract (around 125L daily), and the fact that this is primarily re-absorbed in parts of the intestine downstream from the obstruction.
The first problem with this degree of fluid loss from circulation is one of decreased plasma volume, leading to a reduced [[cardiac output]], and [[acid-base imbalance|acid-base disturbances]].

There also occur serious effects on the intestine itself, which becomes distended due to the trapped fluid, and by gas production from bacteria. It is this distension, and subsequent activation of [[Stretch receptor|stretch receptors]] within the intestinal wall, that leads to the associated pain. With progressive distension of the intestinal wall, there is occlusion of blood vessels, firstly veins, then arteries. The difference in time to onset of occlusion is due to the relatively more rigid walls of arteries compared with veins. This impairment of blood supply leads firstly to [[hyperaemia]] and congestion, and ultimately to [[ischaemic]] [[necrosis]] and [[cellular death]]. The poor blood supply also has effects on the vascular endothelium, leading to an increased permeability. This results initially in leakage of [[plasma]], and eventually blood into the intestinal lumen. In the opposite fashion, [[gram-negative]] bacteria and [[endotoxin]]s can enter the bloodstream, leading to further systemic effects.

===Strangulating Infarction===
Strangulating infarctions have all the same pathological features as a simple obstruction, but the bloody supply is immediately affected. Both arteries and veins may be effected immediately, or progressively as in simple obstruction. Common causes of strangulating obstruction are pedunculated lipomas, and displacement of intestine through a hole, such as a [[hernia]], a mesenteric rent, or the [[epiploic foramen]].

===Non-strangulating Infarction===
In a non-strangulating infarction, blood supply to a section of intestine is occluded, without any obstruction to ingesta present within the intestinal lumen. The most common cause is infection with ''Strongylus vulgaris'' larvae, which develop within the (primarily cranial) [[mesenteric artery]].

==Classification==
===Medical Conditions===
====Stomach====
=====Food engorgement=====
This is a life threatening condition, with a great risk of gastric rupture, and also of secondary [[laminitis]]. It is caused by excess food intake, for example, a horse that has broken into a food store.

=====Gastric/pyloric spasm=====
This commonly affects racehorses, immediately after racing, and is known colloquially as 'racehorse colic'. Typically, the animal will have had access to cold water, but this is not always the case. Although the signs of colic seen may be very violent, this condition is not associated with any risk of gastric rupture. [[Spasmolytic]] drugs are ineffective in treatment, however, naso-gastric intubation is immediately curative.
=====Inappropriate feed/poor [[mastication]]=====
Either of these may lead to a condition where the stomach is unable to efficiently empty. A common example is feeding of unsoaked [[sugar beet]], which then expands within the stomach.

=====Neurological [[atony]]=====
A [[chronic]] motility dysfunction, leading to a slow filling of the stomach with [[ingesta]]. Inhibition of gastric outflow is not normally a feature, and therefore gastric rupture is not a risk. A mild colic may be seen, but far more common is poor condition and reduced performance. [[Warmblood]] horses are more commonly affected than other breeds, leading to the suggestion that there may be a genetic component to the disorder.

=====[[Ulceration]]=====
[[Image:Benign_gastric_ulcer_1.jpg?|thumb|right|A benign gastric ulcer]]
Equine Gastric Ulcer Syndrome (EGUS) is a common cause of mild to moderate colic, and is more prevalent than had been appreciated. In racehorses, the prevalence is as high as 90%. In other performance horses, prevalence ranges from 40-60%. In foals, prevalence is approximately 25%, and probably higher in those being hospitalized for other reasons.

In adult horses, ulceration commonly occurs in the non-glandular portion of the stomach, unlike in humans, where [[peptic ulcers]] are far more common. While the bacterium ''Helicobacter pylori'' is a common cause of ulcers in humans, equine gastric ulcers are not typically infectious in origin. It is thought that EGUS is often stress-related, such as after travelling or confinement, and gastric ulceration is a known potential side-effect of treatment with [[non-steroidal anti-inflammatory drugs|non-steroidal anti-inflammatory drugs]]. A diet consisting of a high proportion of concentrates is also considered a risk factor. In affected horses, pain is often associated with eating, and the horse typically takes one or two bites of food, then no more. A definitive diagnosis requires [[endoscopy]]. Treatment is usually effected using [[H2 antagonist|H2 receptor antagonists]], such as [[Cimetidine]], or [[proton pump inhibitors]], such as [[Omeprazole]].

=====[[Neoplasia]]=====
A [[malignant]] [[squamous]] [[carcinoma]] can effect the [[cardia]] and upper squamous regions of the stomach, resulting in a persistent mild colic, commonly seen soon after feeding. Weight loss and general ill health are usually seen, and the prognosis is very poor, due to the high risk of [[metastasis]].
====Small Intestine====
=====Spasmodic colic=====
Spasmodic colic accounts for a large proportion of colic cases seen in first-opinion practice, however, little is known about its causes. It generally produces a mild colic, due to increased [[peristaltis|peristaltic]] activity in the gastro-intestinal tract. Cases are usually easily resolved by treating with a [[spasmolytic]] such as [[Buscopan]], and a mild [[analgesic]] such as [[phenylbutazone]].
=====[[Grass sickness]]=====
Equine grass sickness, or equine [[dysautonomia]] causes a paralysis of the gastro-intestinal tract, by disruption of the [[autonomic nervous system]]. This leads to a pooling of ingesta throughout all parts of the gastro-intestinal tract. The condition may occur acutely, or progress chronically over several weeks, but all cases will eventually die. A definitive diagnosis is obtained by taking an ileal [[biopsy]], and inspecting the intrinsic [[myenteric plexus]]. There is no effective treatment, although in the short to medium term, horses can be successfully managed by informed and attentive owners.

====Caecum====
=====Flatulent colic=====
Flatulent, or gas colic, occurs when caecal gases are produced faster than they can be removed by the caecum and colon, leading to a distension of the caecum. A diagnosis is strongly confirmed by a right sided abdominal distension, and [[auscultation]]/percussion of tympanitic sounds. Treatment involves withdrawal of fluid, and intra-venous fluid therapy. The distension can be relieved by [[trocharisation]] of the caecal head, via the right sub-lumbar fossa, which is ideally performed using ultrasound guidance.

====Large Colon====
=====Pelvic flexure impaction=====
A relatively common form of colic, that is often associated with a recent change in diet, management or exercise levels. Pain is moderate, and often persists despite adequate [[analgesia]], a sign more commonly associated with colic of a surgical nature. However, rectal examination provides a definitive diagnosis, with a large, doughy structure occupying much of the pelvis. Treatment involves encouraging fluid output into the large colon, to help soften the impaction, firstly by ensuring adequate hydration with intra-venous fluids, and sometimes by administration of [[sodium chloride]] and sodium sulphate orally, to create an [[osmotic]] gradient. Large volumes of water, sometimes with Magnesium Sulfate with or without liquid paraffin ([[Mineral oil]]) are also given by naso-gastric tube, to help soften the impaction and encourage its movement.

=====Left dorsal displacement=====
Left dorsal displacement, or nephrosplenic entrapment, is a frequent cause of colic, where the left dorsal and ventral colon become displaced, and then trapped by the [[spleen]] laterally, the [[kidney]] medially, and the [[nephrosplenic ligament]] ventrally. It can be diagnosed by rectal examination. The first line of treatment is intra-venous [[phenylephrine]] injection, which acts to contract the spleen, so helping release the trapped colon. This is often combined with gentle exercise to encourage movement of the abdominal contents. Circling on the left rein is considered particularly helpful, as it increases the potential space between the spleen and the body wall, allowing more room for the colon to return to its normal location. If this fails, then general anaesthesia is needed. Replacement of the colon is then attempted by rolling of the horse. If this also fails then surgery is needed to correct the displacement.

====Small Colon====
=====Pelvic masses=====
A persistent mild colic may be found when intra-pelvic masses impinge upon the gastro-intestinal tract. Most commonly these are haematomas. Peri-anal lesions, such as [[melanomas]] may also produce these signs.

=====Neurological deficits=====
A complete or partial paralysis of the small colon and rectum may occur with [[polyneuritis equi]], resulting in a lack of faecal expulsion, and consequent obstruction. A diagnosis is made via a neurological examination. Treatment is palliative only, although the condition can be managed for many years by manual emptying of the rectum.

===Surgical Conditions===
====Small Intestine====
=====Impaction=====
Association with ascarid infection<ref>Cribb NC, Cote NM, Bouré LP, Peregrine AS. (2006). ''Acute small intestinal obstruction associated with Parascaris equorum infection in young horses: 25 cases (1985-2004).''. New Zealand Veterinary Journal</ref>

=====Intussusception=====
This is a condition in which one part of the intestine "telescopes" inside another. Usually this obstructs the blood flow to the inner part, and so forms a strangulating obstruction. Intussusception can occur within the small intestine, and also between small intestine and caecum (ileo-caecal intussusception). The latter is predisposed by Anoplocephala perfoliata tapeworm infection. When working up an acute abdominal case, it must be borne in mind that this form of colic is serious and necessitates surgery, however, peritoneal fluid changes will not usually be seen, as will often be found in a surgical colic. This is because the strangulated portion of gut (the inside of the "telescope"), is contained within an intact piece of intestine, so leaking fluid and protein is contained from the peritoneal cavity.

=====Herniation/entrapment=====
*Inguinal canal
*Umbilical hernia
*Epiploic foramen
*Mesenteric rents/tears
*Diaphragmatic hernia
*Mesodiverticular bands
*Gastrosplenic ligament

=====Pedunculated lipoma=====
=====Volvulus (nodosus)=====
=====Rotation of mesenteric root=====
====Caecum====
=====Caeco-caecal intussusception=====
=====Torsion=====
=====Impaction=====
====Large Colon====
=====Torsion=====
=====Left dorsal displacement=====
=====Right dorsal displacement=====

=====Sand impaction=====

=====Enterolith=====

====Small Colon====
=====Faecolith=====

=====Enterolith=====

=====Strangulating lipoma=====

====Any location====
=====Foreign body=====
===False colic===
Signs of colic may be caused by abdominal pain not associated with the gastro-intestinal tract, for example, pain associated with uterine or [[testis|testicular]] torsion, or originating from the [[kidney]]s, [[liver]], [[ovary|ovaries]], spleen, [[pleuritis]], or pleuropneumonia. Other diseases which sometimes cause symptoms which appear similar to colic include [[laminitis]] and [[Equine Exertional Rhabdomyolysis|exertional rhabdomyolysis]].

==Diagnosis==
Many different diagnostic tests can be used to diagnose the cause of equine colic, which may have greater or lesser value in certain situations. The most important distinction to make is whether the condition should be managed medically or surgically. If surgery is indicated, then it must be performed with utmost haste, as delay is a dire prognostic indicator.

===History===
A thorough history is always taken, including age, sex, recent activity, diet, any recent dietary changes, and routine anthelmintic treatment. However, the most important factor is time elapsed since onset of clinical signs, as this has a profound impact on prognosis, and the type of treatment that will be undertaken.

===Cardiovascular Parameters===
Heart rate rises with progression of colic, in part due to pain, but mainly due to decreased circulating volume, decreased [[preload]], and [[endotoxemia]]. The rate should be measured over time, and its response to analgesic therapy ascertained. A pulse that continues to rise in the face of adequate analgesia is considered a surgical indication.
[[Mucous membrane]] colour can be assessed to appreciate the severity of haemodynamic compromise. Reddening of membranes reflects worse prognosis, and [[cyanotic]] membranes indicate a very poor chance of a positive outcome.

Laboratory tests can be performed to assess the cardiovascular status of the patient. [[Packed Cell Volume]] (PCV) is a measure of hydration status, with a value 45% being considered significant. Increasing values over repeated examination are also considered significant. The total protein (TP) of blood may also be measured, as an aid in estimating the amount of protein loss into the intestine. Its value must be interpreted along with the PCV, to take into account the hydration status. Blood lactate levels are useful in determining severity of disease, and as a prognostic indicator; levels between 1-2mmol/L are considered normal, while levels above 5.7mmol/L are considered significant. "Colic scores" that combine several parameters can be relatively accurate prognostic indicators, although most laboratory tests have limited use in terms of specific diagnosis.

===Rectal Examination===
Repeated rectal examinations are a cornerstone of colic diagnosis, as many large intestinal conditions can be definitively diagnosed by this method alone. Other non-specific findings, such as dilated small intestinal loops, may also be detected, and can play a major part in determining if surgery is necessary.

===Naso-gastric Intubation===
Passing a Naso-Gastric Tube (NGT) is useful both diagnostically and therapeutically. Fluid is refluxed from the stomach, and any more than 2 litres of fluid is considered to be significant. Increased fluid is generally a result of backing up of fluid through the intestinal tract, due to a downstream obstruction. This finding is important as it represents a relatively advanced stage of colic, and is often a surgical indication. Therapeutically, gastric decompression is important, since horses are unable to vomit. If fluid build up occurs, gastric rupture may occur, which is inevitably fatal.

===Abdominocentesis===
The extraction of fluid from the peritoneum can be useful in assessing the state of the intestines. A [[sanguinous]] fluid can be caused by an [[infarction]], which indicates surgery is necessary. However, sanguinous fluid can also be caused by external trauma (e.g. rib fractures), middle uterine artery rupture in post-foaling mares, or by inadvertent bleeding caused by the procedure itself. A cloudy fluid is suggestive of an increased number of white blood cells, which indicates the disease is relatively advanced. The protein level of abdominal fluid can be analysed, and may also give information as to the integrity of intestinal blood vessels. Elevated lactate levels in the sample can also give an indication of the degree of compromise to bowel, particularly as a peritoneal:peripheral lactate ratio. Peritoneal fluid that contains food material can indicate rupture of the gastro-intestinal tract, although care should be taken that intestine has not been punctured inadvertently.
A normal peritoneal fluid sample does not rule out a strangulating lesion. For example, in the case of a diaphragmatic hernia, the strangulating gut is contained within the thoracic cavity, so will not affect fluid within the abdominal cavity. A similar situation is true of intussuception, where the strangulating gut is contained with another piece of non-strangulating gut.

===Abdominal Distension===
Any degree of abdominal distension is usually indicative of a condition affecting the large intestines, as distension of structures upstream of here would not be large enough to be visible externally.

===Auscultation===
Auscultation of the abdomen, usually performed in a four quadrant approach, can be a useful tool. Auscultation of the ventral abdomen can also be useful in regions where sand impaction is common. Increased gut sounds are not usually found with major changes, and may be indicative of spasmodic colic, or impending diarrhea. A decreased amount of sound, or no sound, may be suggestive of serious changes. Trapped gas, particularly in the caecum, can often be heard by "pinging", where a flick of the finger against the skin over the affected area causes a sharp sound audible through the stethoscope. This sound is sometimes compared to the ringing sound made by a rubber ball hitting a solid surface.

===Faecal Examination===
The amount of faeces produced, and its character can be helpful, although as changes often occur relatively distant to the anus, changes may not be seen for some time. In areas where sand colic is known to be common, or if the history suggests it may be a possibility, faeces can be examined for the presence of sand, often by immersion in water, or simply by its texture. The presence of diarrhoea is common in sand colic, and can be seen in horses with enteroliths. Otherwise, diarrhoea is usually indicative of a non-surgical condition, although it can be associated with life threatening conditions such as [[salmonellosis]].

===Abdominal Ultrasound===
Ultrasonographic evaluation of the abdomen is extremely useful in characterizing certain components of the disease process. The amount and character of free abdominal fluid can be determined, as well as the determination of a specific place for safe, high-yield abdominocentesis. The appearance of small intestine, including distension, wall thickness and motility (or lack thereof, often seen as sedimentatioon of digesta) can be extremely important in the decision for surgical or medical therapy. The large colon and cecum can be evaluated for wall thickness (particularly useful in cases of right dorsal colitis), fluidy contents (colitis/diarrhea), and sometimes displacement. The presence of mesenteric vessels associated with the large colon is generally associated with displacement. The normal anti-mesenteric vessels of the cecum can be used to trace its course. Ventral displacement of the spleen with obscuring of the left kidney is associated with nephro-splenic displacement. Visualization of sacculated large bowel immediately ventral to the liver or spleen, or non-sacculated large bowel in the ventral abdomen suggests displacement. The stomach can be evaluated for distension and abnormalities of the wall. Abdominal ultrasound is useful in detecting diaphragmatic or inguinal herniation. Abnormalities of the liver or kidneys, both potential causes of false colic, are often detectable with ultrasound.

==Clinical signs==
*Pawing and/or scraping
*Stretching
*Frequent attempts to urinate
*Flank watching
*Pacing
*Repeated [[flehmen]] response
*Repeated lying down and rising
*Rolling
*Groaning
*[[Bruxism]]
*Excess salivation
*Inappetance
*Decreased faecal output
*Increased pulse rate
*Dark mucous membranes

==Medical Treatment==

==Surgical Treatment==

==Post-surgical Management==

==Prevention==

==Epidemiology==

===Incidence===
Colic occurs relatively frequently in horses, with an incidence estimated at 0.1-0.2 episodes per horse-year. In context, this would mean an average holding of 100 horses could reasonably expect to see 10-20 cases every year.

===Classification===
Approximately 90% of colic episodes can be succesfully managed using medical treatments, with the remainder requiring surgery. Assuming surgical and medical cases of colic are accurately distinguished, survival rates of 95% and 80% are considered normal for medical and surgical colic, respectively.

===Post-operative Survival===
Studies have shown that there is an increased risk of death with certain factors:
*Abnormal [[hematocrit|Packed Cell Volume]] (PCV) on presentation
*Increased length of intestine resected
*Increased duration of surgery
*Elevated peripheral lactate
*Elevated peritoneal fluid lactate

==See Also==
*[[equine anatomy#Digestive system|Equine gastrointestinal anatomy]]
*[[Equine nutrition]]

==Further Reading==

==References==
{{reflist}}

Colic

2009-04-06T19:13:23Z

Alsiola: /* Intussusception */

{{unfinished}}
{{horse}}

'''Colic in [[horse]]s''' is defined as [[abdominal pain]], and can be caused by a wide variety of conditions. Many of these conditions are life threatening, and therefore it is essential to diagnose and treat cases of colic as quickly as possible. The most common causes of colic are [[Gastrointestinal tract|gastrointestinal]] conditions, although it can also be caused by other abdominal conditions. In the latter case, it is often called false colic. Treatment of colic is largely dependent upon identifying the underlying reason for the pain, and treating this cause appropriately. Most commonly this is done [[medicine|medically]], but in a small percentage of cases, [[surgery|surgical intervention]] is needed. Among [[domesticated]] horses, colic is a major cause of premature death. The incidence of colic in the general horse population has been estimated between 10 and 20 percent on an annual basis. It is important that any person who owns or works with horses be able to recognize the signs of colic, so that a [[veterinarian]] may be called promptly.

==Pathophysiology==
This can be divided broadly into simple obstructions, strangulating obstructions, and non-strangulating [[infarctions]].

===Simple Obstruction===
This is characterised by a physical obstruction of the intestine, which can be due to impacted food material, [[stricture]] formation, or foreign bodies. The primary pathophysiological abnormality caused by this obstruction is related to the trapping of fluid within the intestine oral to the obstruction. This is due to the large amount of fluid produced in the upper gastro-intestinal tract (around 125L daily), and the fact that this is primarily re-absorbed in parts of the intestine downstream from the obstruction.
The first problem with this degree of fluid loss from circulation is one of decreased plasma volume, leading to a reduced [[cardiac output]], and [[acid-base imbalance|acid-base disturbances]].

There also occur serious effects on the intestine itself, which becomes distended due to the trapped fluid, and by gas production from bacteria. It is this distension, and subsequent activation of [[Stretch receptor|stretch receptors]] within the intestinal wall, that leads to the associated pain. With progressive distension of the intestinal wall, there is occlusion of blood vessels, firstly veins, then arteries. The difference in time to onset of occlusion is due to the relatively more rigid walls of arteries compared with veins. This impairment of blood supply leads firstly to [[hyperaemia]] and congestion, and ultimately to [[ischaemic]] [[necrosis]] and [[cellular death]]. The poor blood supply also has effects on the vascular endothelium, leading to an increased permeability. This results initially in leakage of [[plasma]], and eventually blood into the intestinal lumen. In the opposite fashion, [[gram-negative]] bacteria and [[endotoxin]]s can enter the bloodstream, leading to further systemic effects.

===Strangulating Infarction===
Strangulating infarctions have all the same pathological features as a simple obstruction, but the bloody supply is immediately affected. Both arteries and veins may be effected immediately, or progressively as in simple obstruction. Common causes of strangulating obstruction are pedunculated lipomas, and displacement of intestine through a hole, such as a [[hernia]], a mesenteric rent, or the [[epiploic foramen]].

===Non-strangulating Infarction===
In a non-strangulating infarction, blood supply to a section of intestine is occluded, without any obstruction to ingesta present within the intestinal lumen. The most common cause is infection with ''Strongylus vulgaris'' larvae, which develop within the (primarily cranial) [[mesenteric artery]].

==Classification==
===Medical Conditions===
====Stomach====
=====Food engorgement=====
This is a life threatening condition, with a great risk of gastric rupture, and also of secondary [[laminitis]]. It is caused by excess food intake, for example, a horse that has broken into a food store.

=====Gastric/pyloric spasm=====
This commonly affects racehorses, immediately after racing, and is known colloquially as 'racehorse colic'. Typically, the animal will have had access to cold water, but this is not always the case. Although the signs of colic seen may be very violent, this condition is not associated with any risk of gastric rupture. [[Spasmolytic]] drugs are ineffective in treatment, however, naso-gastric intubation is immediately curative.
=====Inappropriate feed/poor [[mastication]]=====
Either of these may lead to a condition where the stomach is unable to efficiently empty. A common example is feeding of unsoaked [[sugar beet]], which then expands within the stomach.

=====Neurological [[atony]]=====
A [[chronic]] motility dysfunction, leading to a slow filling of the stomach with [[ingesta]]. Inhibition of gastric outflow is not normally a feature, and therefore gastric rupture is not a risk. A mild colic may be seen, but far more common is poor condition and reduced performance. [[Warmblood]] horses are more commonly affected than other breeds, leading to the suggestion that there may be a genetic component to the disorder.

=====[[Ulceration]]=====
[[Image:Benign_gastric_ulcer_1.jpg?|thumb|right|A benign gastric ulcer]]
Equine Gastric Ulcer Syndrome (EGUS) is a common cause of mild to moderate colic, and is more prevalent than had been appreciated. In racehorses, the prevalence is as high as 90%. In other performance horses, prevalence ranges from 40-60%. In foals, prevalence is approximately 25%, and probably higher in those being hospitalized for other reasons.

In adult horses, ulceration commonly occurs in the non-glandular portion of the stomach, unlike in humans, where [[peptic ulcers]] are far more common. While the bacterium ''Helicobacter pylori'' is a common cause of ulcers in humans, equine gastric ulcers are not typically infectious in origin. It is thought that EGUS is often stress-related, such as after travelling or confinement, and gastric ulceration is a known potential side-effect of treatment with [[non-steroidal anti-inflammatory drugs|non-steroidal anti-inflammatory drugs]]. A diet consisting of a high proportion of concentrates is also considered a risk factor. In affected horses, pain is often associated with eating, and the horse typically takes one or two bites of food, then no more. A definitive diagnosis requires [[endoscopy]]. Treatment is usually effected using [[H2 antagonist|H2 receptor antagonists]], such as [[Cimetidine]], or [[proton pump inhibitors]], such as [[Omeprazole]].

=====[[Neoplasia]]=====
A [[malignant]] [[squamous]] [[carcinoma]] can effect the [[cardia]] and upper squamous regions of the stomach, resulting in a persistent mild colic, commonly seen soon after feeding. Weight loss and general ill health are usually seen, and the prognosis is very poor, due to the high risk of [[metastasis]].
====Small Intestine====
=====Spasmodic colic=====
Spasmodic colic accounts for a large proportion of colic cases seen in first-opinion practice, however, little is known about its causes. It generally produces a mild colic, due to increased [[peristaltis|peristaltic]] activity in the gastro-intestinal tract. Cases are usually easily resolved by treating with a [[spasmolytic]] such as [[Buscopan]], and a mild [[analgesic]] such as [[phenylbutazone]].
=====[[Grass sickness]]=====
Equine grass sickness, or equine [[dysautonomia]] causes a paralysis of the gastro-intestinal tract, by disruption of the [[autonomic nervous system]]. This leads to a pooling of ingesta throughout all parts of the gastro-intestinal tract. The condition may occur acutely, or progress chronically over several weeks, but all cases will eventually die. A definitive diagnosis is obtained by taking an ileal [[biopsy]], and inspecting the intrinsic [[myenteric plexus]]. There is no effective treatment, although in the short to medium term, horses can be successfully managed by informed and attentive owners.

====Caecum====
=====Flatulent colic=====
Flatulent, or gas colic, occurs when caecal gases are produced faster than they can be removed by the caecum and colon, leading to a distension of the caecum. A diagnosis is strongly confirmed by a right sided abdominal distension, and [[auscultation]]/percussion of tympanitic sounds. Treatment involves withdrawal of fluid, and intra-venous fluid therapy. The distension can be relieved by [[trocharisation]] of the caecal head, via the right sub-lumbar fossa, which is ideally performed using ultrasound guidance.

====Large Colon====
=====Pelvic flexure impaction=====
A relatively common form of colic, that is often associated with a recent change in diet, management or exercise levels. Pain is moderate, and often persists despite adequate [[analgesia]], a sign more commonly associated with colic of a surgical nature. However, rectal examination provides a definitive diagnosis, with a large, doughy structure occupying much of the pelvis. Treatment involves encouraging fluid output into the large colon, to help soften the impaction, firstly by ensuring adequate hydration with intra-venous fluids, and sometimes by administration of [[sodium chloride]] and sodium sulphate orally, to create an [[osmotic]] gradient. Large volumes of water, sometimes with Magnesium Sulfate with or without liquid paraffin ([[Mineral oil]]) are also given by naso-gastric tube, to help soften the impaction and encourage its movement.

=====Left dorsal displacement=====
Left dorsal displacement, or nephrosplenic entrapment, is a frequent cause of colic, where the left dorsal and ventral colon become displaced, and then trapped by the [[spleen]] laterally, the [[kidney]] medially, and the [[nephrosplenic ligament]] ventrally. It can be diagnosed by rectal examination. The first line of treatment is intra-venous [[phenylephrine]] injection, which acts to contract the spleen, so helping release the trapped colon. This is often combined with gentle exercise to encourage movement of the abdominal contents. Circling on the left rein is considered particularly helpful, as it increases the potential space between the spleen and the body wall, allowing more room for the colon to return to its normal location. If this fails, then general anaesthesia is needed. Replacement of the colon is then attempted by rolling of the horse. If this also fails then surgery is needed to correct the displacement.

====Small Colon====
=====Pelvic masses=====
A persistent mild colic may be found when intra-pelvic masses impinge upon the gastro-intestinal tract. Most commonly these are haematomas. Peri-anal lesions, such as [[melanomas]] may also produce these signs.

=====Neurological deficits=====
A complete or partial paralysis of the small colon and rectum may occur with [[polyneuritis equi]], resulting in a lack of faecal expulsion, and consequent obstruction. A diagnosis is made via a neurological examination. Treatment is palliative only, although the condition can be managed for many years by manual emptying of the rectum.

===Surgical Conditions===
====Small Intestine====
=====Impaction=====
Association with ascarid infection<ref>Cribb NC, Cote NM, Bouré LP, Peregrine AS. (2006). ''Acute small intestinal obstruction associated with Parascaris equorum infection in young horses: 25 cases (1985-2004).''. New Zealand Veterinary Journal</ref>

=====Intussusception=====
This is a condition in which one part of the intestine "telescopes" inside another. Usually this obstructs the blood flow to the inner part, and so forms a strangulating obstruction. Intussusception can occur within the small intestine, and also between small intestine and caecum (ileo-caecal intussusception). The latter is predisposed by Anoplocephala perfoliata tapeworm infection. When working up an acute abdominal case, it must be borne in mind that this form of colic is serious and necessitates surgery, however, peritoneal fluid changes will not usually be seen, as will often be found in a surgical colic. This is because the strangulated portion of gut (the inside of the "telescope"), is contained within an intact piece of intestine, so leaking fluid and protein is contained from the peritoneal cavity.

=====Herniation/entrapment=====
*Inguinal canal
*Umbilical hernia
*Epiploic foramen
*Mesenteric rents/tears
*Diaphragmatic hernia
*Mesodiverticular bands
*Gastrosplenic ligament

=====Pedunculated lipoma=====
=====Volvulus (nodosus)=====
=====Rotation of mesenteric root=====
====Caecum====
=====Caeco-caecal intussusception=====
=====Torsion=====
=====Impaction=====
====Large Colon====
=====Torsion=====
=====Left dorsal displacement=====
=====Right dorsal displacement=====

=====Sand impaction=====

=====Enterolith=====

====Small Colon====
=====Faecolith=====

=====Enterolith=====

=====Strangulating lipoma=====

====Any location====
=====Foreign body=====
===False colic===
Signs of colic may be caused by abdominal pain not associated with the gastro-intestinal tract, for example, pain associated with uterine or [[testis|testicular]] torsion, or originating from the [[kidney]]s, [[liver]], [[ovary|ovaries]], spleen, [[pleuritis]], or pleuropneumonia. Other diseases which sometimes cause symptoms which appear similar to colic include [[laminitis]] and [[Equine Exertional Rhabdomyolysis|exertional rhabdomyolysis]].

==Diagnosis==
Many different diagnostic tests can be used to diagnose the cause of equine colic, which may have greater or lesser value in certain situations. The most important distinction to make is whether the condition should be managed medically or surgically. If surgery is indicated, then it must be performed with utmost haste, as delay is a dire prognostic indicator.

===History===
A thorough history is always taken, including age, sex, recent activity, diet, any recent dietary changes, and routine anthelmintic treatment. However, the most important factor is time elapsed since onset of clinical signs, as this has a profound impact on prognosis, and the type of treatment that will be undertaken.

===Cardiovascular Parameters===
Heart rate rises with progression of colic, in part due to pain, but mainly due to decreased circulating volume, decreased [[preload]], and [[endotoxemia]]. The rate should be measured over time, and its response to analgesic therapy ascertained. A pulse that continues to rise in the face of adequate analgesia is considered a surgical indication.
[[Mucous membrane]] colour can be assessed to appreciate the severity of haemodynamic compromise. Reddening of membranes reflects worse prognosis, and [[cyanotic]] membranes indicate a very poor chance of a positive outcome.

Laboratory tests can be performed to assess the cardiovascular status of the patient. [[Packed Cell Volume]] (PCV) is a measure of hydration status, with a value 45% being considered significant. Increasing values over repeated examination are also considered significant. The total protein (TP) of blood may also be measured, as an aid in estimating the amount of protein loss into the intestine. Its value must be interpreted along with the PCV, to take into account the hydration status. Blood lactate levels are useful in determining severity of disease, and as a prognostic indicator; levels between 1-2mmol/L are considered normal, while levels above 5.7mmol/L are considered significant. "Colic scores" that combine several parameters can be relatively accurate prognostic indicators, although most laboratory tests have limited use in terms of specific diagnosis.

===Rectal Examination===
Repeated rectal examinations are a cornerstone of colic diagnosis, as many large intestinal conditions can be definitively diagnosed by this method alone. Other non-specific findings, such as dilated small intestinal loops, may also be detected, and can play a major part in determining if surgery is necessary.

===Naso-gastric Intubation===
Passing a Naso-Gastric Tube (NGT) is useful both diagnostically and therapeutically. Fluid is refluxed from the stomach, and any more than 2 litres of fluid is considered to be significant. Increased fluid is generally a result of backing up of fluid through the intestinal tract, due to a downstream obstruction. This finding is important as it represents a relatively advanced stage of colic, and is often a surgical indication. Therapeutically, gastric decompression is important, since horses are unable to vomit. If fluid build up occurs, gastric rupture may occur, which is inevitably fatal.

===Abdominocentesis===
The extraction of fluid from the peritoneum can be useful in assessing the state of the intestines. A [[sanguinous]] fluid can be caused by an [[infarction]], which indicates surgery is necessary. However, sanguinous fluid can also be caused by external trauma (e.g. rib fractures), middle uterine artery rupture in post-foaling mares, or by inadvertent bleeding caused by the procedure itself. A cloudy fluid is suggestive of an increased number of white blood cells, which indicates the disease is relatively advanced. The protein level of abdominal fluid can be analysed, and may also give information as to the integrity of intestinal blood vessels. Elevated lactate levels in the sample can also give an indication of the degree of compromise to bowel, particularly as a peritoneal:peripheral lactate ratio. Peritoneal fluid that contains food material can indicate rupture of the gastro-intestinal tract, although care should be taken that intestine has not been punctured inadvertently.
A normal peritoneal fluid sample does not rule out a strangulating lesion. For example, in the case of a diaphragmatic hernia, the strangulating gut is contained within the thoracic cavity, so will not affect fluid within the abdominal cavity. A similar situation is true of intussuception, where the strangulating gut is contained with another piece of non-strangulating gut.

===Abdominal Distension===
Any degree of abdominal distension is usually indicative of a condition affecting the large intestines, as distension of structures upstream of here would not be large enough to be visible externally.

===Auscultation===
Auscultation of the abdomen, usually performed in a four quadrant approach, can be a useful tool. Auscultation of the ventral abdomen can also be useful in regions where sand impaction is common. Increased gut sounds are not usually found with major changes, and may be indicative of spasmodic colic, or impending diarrhea. A decreased amount of sound, or no sound, may be suggestive of serious changes. Trapped gas, particularly in the caecum, can often be heard by "pinging", where a flick of the finger against the skin over the affected area causes a sharp sound audible through the stethoscope. This sound is sometimes compared to the ringing sound made by a rubber ball hitting a solid surface.

===Faecal Examination===
The amount of faeces produced, and its character can be helpful, although as changes often occur relatively distant to the anus, changes may not be seen for some time. In areas where sand colic is known to be common, or if the history suggests it may be a possibility, faeces can be examined for the presence of sand, often by immersion in water, or simply by its texture. The presence of diarrhoea is common in sand colic, and can be seen in horses with enteroliths. Otherwise, diarrhoea is usually indicative of a non-surgical condition, although it can be associated with life threatening conditions such as [[salmonellosis]].

===Abdominal Ultrasound===
Ultrasonographic evaluation of the abdomen is extremely useful in characterizing certain components of the disease process. The amount and character of free abdominal fluid can be determined, as well as the determination of a specific place for safe, high-yield abdominocentesis. The appearance of small intestine, including distension, wall thickness and motility (or lack thereof, often seen as sedimentatioon of digesta) can be extremely important in the decision for surgical or medical therapy. The large colon and cecum can be evaluated for wall thickness (particularly useful in cases of right dorsal colitis), fluidy contents (colitis/diarrhea), and sometimes displacement. The presence of mesenteric vessels associated with the large colon is generally associated with displacement. The normal anti-mesenteric vessels of the cecum can be used to trace its course. Ventral displacement of the spleen with obscuring of the left kidney is associated with nephro-splenic displacement. Visualization of sacculated large bowel immediately ventral to the liver or spleen, or non-sacculated large bowel in the ventral abdomen suggests displacement. The stomach can be evaluated for distension and abnormalities of the wall. Abdominal ultrasound is useful in detecting diaphragmatic or inguinal herniation. Abnormalities of the liver or kidneys, both potential causes of false colic, are often detectable with ultrasound.

==Clinical signs==
*Pawing and/or scraping
*Stretching
*Frequent attempts to urinate
*Flank watching
*Pacing
*Repeated [[flehmen]] response
*Repeated lying down and rising
*Rolling
*Groaning
*[[Bruxism]]
*Excess salivation
*Inappetance
*Decreased faecal output
*Increased pulse rate
*Dark mucous membranes

==Medical Treatment==

==Surgical Treatment==

==Post-surgical Management==

==Prevention==

==Epidemiology==

===Incidence===
Colic occurs relatively frequently in horses, with an incidence estimated at 0.1-0.2 episodes per horse-year. In context, this would mean an average holding of 100 horses could reasonably expect to see 10-20 cases every year.

===Classification===
Approximately 90% of colic episodes can be succesfully managed using medical treatments, with the remainder requiring surgery. Assuming surgical and medical cases of colic are accurately distinguished, survival rates of 95% and 80% are considered normal for medical and surgical colic, respectively.

===Post-operative Survival===
Studies have shown that there is an increased risk of death with certain factors:
*Abnormal [[hematocrit|Packed Cell Volume]] (PCV) on presentation
*Increased length of intestine resected
*Increased duration of surgery
*Elevated peripheral lactate

==See Also==
*[[equine anatomy#Digestive system|Equine gastrointestinal anatomy]]
*[[Equine nutrition]]

==Further Reading==

==References==
{{reflist}}

Colic

2009-04-06T19:08:31Z

Alsiola:

{{unfinished}}
{{horse}}

'''Colic in [[horse]]s''' is defined as [[abdominal pain]], and can be caused by a wide variety of conditions. Many of these conditions are life threatening, and therefore it is essential to diagnose and treat cases of colic as quickly as possible. The most common causes of colic are [[Gastrointestinal tract|gastrointestinal]] conditions, although it can also be caused by other abdominal conditions. In the latter case, it is often called false colic. Treatment of colic is largely dependent upon identifying the underlying reason for the pain, and treating this cause appropriately. Most commonly this is done [[medicine|medically]], but in a small percentage of cases, [[surgery|surgical intervention]] is needed. Among [[domesticated]] horses, colic is a major cause of premature death. The incidence of colic in the general horse population has been estimated between 10 and 20 percent on an annual basis. It is important that any person who owns or works with horses be able to recognize the signs of colic, so that a [[veterinarian]] may be called promptly.

==Pathophysiology==
This can be divided broadly into simple obstructions, strangulating obstructions, and non-strangulating [[infarctions]].

===Simple Obstruction===
This is characterised by a physical obstruction of the intestine, which can be due to impacted food material, [[stricture]] formation, or foreign bodies. The primary pathophysiological abnormality caused by this obstruction is related to the trapping of fluid within the intestine oral to the obstruction. This is due to the large amount of fluid produced in the upper gastro-intestinal tract (around 125L daily), and the fact that this is primarily re-absorbed in parts of the intestine downstream from the obstruction.
The first problem with this degree of fluid loss from circulation is one of decreased plasma volume, leading to a reduced [[cardiac output]], and [[acid-base imbalance|acid-base disturbances]].

There also occur serious effects on the intestine itself, which becomes distended due to the trapped fluid, and by gas production from bacteria. It is this distension, and subsequent activation of [[Stretch receptor|stretch receptors]] within the intestinal wall, that leads to the associated pain. With progressive distension of the intestinal wall, there is occlusion of blood vessels, firstly veins, then arteries. The difference in time to onset of occlusion is due to the relatively more rigid walls of arteries compared with veins. This impairment of blood supply leads firstly to [[hyperaemia]] and congestion, and ultimately to [[ischaemic]] [[necrosis]] and [[cellular death]]. The poor blood supply also has effects on the vascular endothelium, leading to an increased permeability. This results initially in leakage of [[plasma]], and eventually blood into the intestinal lumen. In the opposite fashion, [[gram-negative]] bacteria and [[endotoxin]]s can enter the bloodstream, leading to further systemic effects.

===Strangulating Infarction===
Strangulating infarctions have all the same pathological features as a simple obstruction, but the bloody supply is immediately affected. Both arteries and veins may be effected immediately, or progressively as in simple obstruction. Common causes of strangulating obstruction are pedunculated lipomas, and displacement of intestine through a hole, such as a [[hernia]], a mesenteric rent, or the [[epiploic foramen]].

===Non-strangulating Infarction===
In a non-strangulating infarction, blood supply to a section of intestine is occluded, without any obstruction to ingesta present within the intestinal lumen. The most common cause is infection with ''Strongylus vulgaris'' larvae, which develop within the (primarily cranial) [[mesenteric artery]].

==Classification==
===Medical Conditions===
====Stomach====
=====Food engorgement=====
This is a life threatening condition, with a great risk of gastric rupture, and also of secondary [[laminitis]]. It is caused by excess food intake, for example, a horse that has broken into a food store.

=====Gastric/pyloric spasm=====
This commonly affects racehorses, immediately after racing, and is known colloquially as 'racehorse colic'. Typically, the animal will have had access to cold water, but this is not always the case. Although the signs of colic seen may be very violent, this condition is not associated with any risk of gastric rupture. [[Spasmolytic]] drugs are ineffective in treatment, however, naso-gastric intubation is immediately curative.
=====Inappropriate feed/poor [[mastication]]=====
Either of these may lead to a condition where the stomach is unable to efficiently empty. A common example is feeding of unsoaked [[sugar beet]], which then expands within the stomach.

=====Neurological [[atony]]=====
A [[chronic]] motility dysfunction, leading to a slow filling of the stomach with [[ingesta]]. Inhibition of gastric outflow is not normally a feature, and therefore gastric rupture is not a risk. A mild colic may be seen, but far more common is poor condition and reduced performance. [[Warmblood]] horses are more commonly affected than other breeds, leading to the suggestion that there may be a genetic component to the disorder.

=====[[Ulceration]]=====
[[Image:Benign_gastric_ulcer_1.jpg?|thumb|right|A benign gastric ulcer]]
Equine Gastric Ulcer Syndrome (EGUS) is a common cause of mild to moderate colic, and is more prevalent than had been appreciated. In racehorses, the prevalence is as high as 90%. In other performance horses, prevalence ranges from 40-60%. In foals, prevalence is approximately 25%, and probably higher in those being hospitalized for other reasons.

In adult horses, ulceration commonly occurs in the non-glandular portion of the stomach, unlike in humans, where [[peptic ulcers]] are far more common. While the bacterium ''Helicobacter pylori'' is a common cause of ulcers in humans, equine gastric ulcers are not typically infectious in origin. It is thought that EGUS is often stress-related, such as after travelling or confinement, and gastric ulceration is a known potential side-effect of treatment with [[non-steroidal anti-inflammatory drugs|non-steroidal anti-inflammatory drugs]]. A diet consisting of a high proportion of concentrates is also considered a risk factor. In affected horses, pain is often associated with eating, and the horse typically takes one or two bites of food, then no more. A definitive diagnosis requires [[endoscopy]]. Treatment is usually effected using [[H2 antagonist|H2 receptor antagonists]], such as [[Cimetidine]], or [[proton pump inhibitors]], such as [[Omeprazole]].

=====[[Neoplasia]]=====
A [[malignant]] [[squamous]] [[carcinoma]] can effect the [[cardia]] and upper squamous regions of the stomach, resulting in a persistent mild colic, commonly seen soon after feeding. Weight loss and general ill health are usually seen, and the prognosis is very poor, due to the high risk of [[metastasis]].
====Small Intestine====
=====Spasmodic colic=====
Spasmodic colic accounts for a large proportion of colic cases seen in first-opinion practice, however, little is known about its causes. It generally produces a mild colic, due to increased [[peristaltis|peristaltic]] activity in the gastro-intestinal tract. Cases are usually easily resolved by treating with a [[spasmolytic]] such as [[Buscopan]], and a mild [[analgesic]] such as [[phenylbutazone]].
=====[[Grass sickness]]=====
Equine grass sickness, or equine [[dysautonomia]] causes a paralysis of the gastro-intestinal tract, by disruption of the [[autonomic nervous system]]. This leads to a pooling of ingesta throughout all parts of the gastro-intestinal tract. The condition may occur acutely, or progress chronically over several weeks, but all cases will eventually die. A definitive diagnosis is obtained by taking an ileal [[biopsy]], and inspecting the intrinsic [[myenteric plexus]]. There is no effective treatment, although in the short to medium term, horses can be successfully managed by informed and attentive owners.

====Caecum====
=====Flatulent colic=====
Flatulent, or gas colic, occurs when caecal gases are produced faster than they can be removed by the caecum and colon, leading to a distension of the caecum. A diagnosis is strongly confirmed by a right sided abdominal distension, and [[auscultation]]/percussion of tympanitic sounds. Treatment involves withdrawal of fluid, and intra-venous fluid therapy. The distension can be relieved by [[trocharisation]] of the caecal head, via the right sub-lumbar fossa, which is ideally performed using ultrasound guidance.

====Large Colon====
=====Pelvic flexure impaction=====
A relatively common form of colic, that is often associated with a recent change in diet, management or exercise levels. Pain is moderate, and often persists despite adequate [[analgesia]], a sign more commonly associated with colic of a surgical nature. However, rectal examination provides a definitive diagnosis, with a large, doughy structure occupying much of the pelvis. Treatment involves encouraging fluid output into the large colon, to help soften the impaction, firstly by ensuring adequate hydration with intra-venous fluids, and sometimes by administration of [[sodium chloride]] and sodium sulphate orally, to create an [[osmotic]] gradient. Large volumes of water, sometimes with Magnesium Sulfate with or without liquid paraffin ([[Mineral oil]]) are also given by naso-gastric tube, to help soften the impaction and encourage its movement.

=====Left dorsal displacement=====
Left dorsal displacement, or nephrosplenic entrapment, is a frequent cause of colic, where the left dorsal and ventral colon become displaced, and then trapped by the [[spleen]] laterally, the [[kidney]] medially, and the [[nephrosplenic ligament]] ventrally. It can be diagnosed by rectal examination. The first line of treatment is intra-venous [[phenylephrine]] injection, which acts to contract the spleen, so helping release the trapped colon. This is often combined with gentle exercise to encourage movement of the abdominal contents. Circling on the left rein is considered particularly helpful, as it increases the potential space between the spleen and the body wall, allowing more room for the colon to return to its normal location. If this fails, then general anaesthesia is needed. Replacement of the colon is then attempted by rolling of the horse. If this also fails then surgery is needed to correct the displacement.

====Small Colon====
=====Pelvic masses=====
A persistent mild colic may be found when intra-pelvic masses impinge upon the gastro-intestinal tract. Most commonly these are haematomas. Peri-anal lesions, such as [[melanomas]] may also produce these signs.

=====Neurological deficits=====
A complete or partial paralysis of the small colon and rectum may occur with [[polyneuritis equi]], resulting in a lack of faecal expulsion, and consequent obstruction. A diagnosis is made via a neurological examination. Treatment is palliative only, although the condition can be managed for many years by manual emptying of the rectum.

===Surgical Conditions===
====Small Intestine====
=====Impaction=====
Association with ascarid infection<ref>Cribb NC, Cote NM, Bouré LP, Peregrine AS. (2006). ''Acute small intestinal obstruction associated with Parascaris equorum infection in young horses: 25 cases (1985-2004).''. New Zealand Veterinary Journal</ref>

=====Intussusception=====
=====Herniation/entrapment=====
*Inguinal canal
*Umbilical hernia
*Epiploic foramen
*Mesenteric rents/tears
*Diaphragmatic hernia
*Mesodiverticular bands
*Gastrosplenic ligament

=====Pedunculated lipoma=====
=====Volvulus (nodosus)=====
=====Rotation of mesenteric root=====
====Caecum====
=====Caeco-caecal intussusception=====
=====Torsion=====
=====Impaction=====
====Large Colon====
=====Torsion=====
=====Left dorsal displacement=====
=====Right dorsal displacement=====

=====Sand impaction=====

=====Enterolith=====

====Small Colon====
=====Faecolith=====

=====Enterolith=====

=====Strangulating lipoma=====

====Any location====
=====Foreign body=====
===False colic===
Signs of colic may be caused by abdominal pain not associated with the gastro-intestinal tract, for example, pain associated with uterine or [[testis|testicular]] torsion, or originating from the [[kidney]]s, [[liver]], [[ovary|ovaries]], spleen, [[pleuritis]], or pleuropneumonia. Other diseases which sometimes cause symptoms which appear similar to colic include [[laminitis]] and [[Equine Exertional Rhabdomyolysis|exertional rhabdomyolysis]].

==Diagnosis==
Many different diagnostic tests can be used to diagnose the cause of equine colic, which may have greater or lesser value in certain situations. The most important distinction to make is whether the condition should be managed medically or surgically. If surgery is indicated, then it must be performed with utmost haste, as delay is a dire prognostic indicator.

===History===
A thorough history is always taken, including age, sex, recent activity, diet, any recent dietary changes, and routine anthelmintic treatment. However, the most important factor is time elapsed since onset of clinical signs, as this has a profound impact on prognosis, and the type of treatment that will be undertaken.

===Cardiovascular Parameters===
Heart rate rises with progression of colic, in part due to pain, but mainly due to decreased circulating volume, decreased [[preload]], and [[endotoxemia]]. The rate should be measured over time, and its response to analgesic therapy ascertained. A pulse that continues to rise in the face of adequate analgesia is considered a surgical indication.
[[Mucous membrane]] colour can be assessed to appreciate the severity of haemodynamic compromise. Reddening of membranes reflects worse prognosis, and [[cyanotic]] membranes indicate a very poor chance of a positive outcome.

Laboratory tests can be performed to assess the cardiovascular status of the patient. [[Packed Cell Volume]] (PCV) is a measure of hydration status, with a value 45% being considered significant. Increasing values over repeated examination are also considered significant. The total protein (TP) of blood may also be measured, as an aid in estimating the amount of protein loss into the intestine. Its value must be interpreted along with the PCV, to take into account the hydration status. Blood lactate levels are useful in determining severity of disease, and as a prognostic indicator; levels between 1-2mmol/L are considered normal, while levels above 5.7mmol/L are considered significant. "Colic scores" that combine several parameters can be relatively accurate prognostic indicators, although most laboratory tests have limited use in terms of specific diagnosis.

===Rectal Examination===
Repeated rectal examinations are a cornerstone of colic diagnosis, as many large intestinal conditions can be definitively diagnosed by this method alone. Other non-specific findings, such as dilated small intestinal loops, may also be detected, and can play a major part in determining if surgery is necessary.

===Naso-gastric Intubation===
Passing a Naso-Gastric Tube (NGT) is useful both diagnostically and therapeutically. Fluid is refluxed from the stomach, and any more than 2 litres of fluid is considered to be significant. Increased fluid is generally a result of backing up of fluid through the intestinal tract, due to a downstream obstruction. This finding is important as it represents a relatively advanced stage of colic, and is often a surgical indication. Therapeutically, gastric decompression is important, since horses are unable to vomit. If fluid build up occurs, gastric rupture may occur, which is inevitably fatal.

===Abdominocentesis===
The extraction of fluid from the peritoneum can be useful in assessing the state of the intestines. A [[sanguinous]] fluid can be caused by an [[infarction]], which indicates surgery is necessary. However, sanguinous fluid can also be caused by external trauma (e.g. rib fractures), middle uterine artery rupture in post-foaling mares, or by inadvertent bleeding caused by the procedure itself. A cloudy fluid is suggestive of an increased number of white blood cells, which indicates the disease is relatively advanced. The protein level of abdominal fluid can be analysed, and may also give information as to the integrity of intestinal blood vessels. Elevated lactate levels in the sample can also give an indication of the degree of compromise to bowel, particularly as a peritoneal:peripheral lactate ratio. Peritoneal fluid that contains food material can indicate rupture of the gastro-intestinal tract, although care should be taken that intestine has not been punctured inadvertently.
A normal peritoneal fluid sample does not rule out a strangulating lesion. For example, in the case of a diaphragmatic hernia, the strangulating gut is contained within the thoracic cavity, so will not affect fluid within the abdominal cavity. A similar situation is true of intussuception, where the strangulating gut is contained with another piece of non-strangulating gut.

===Abdominal Distension===
Any degree of abdominal distension is usually indicative of a condition affecting the large intestines, as distension of structures upstream of here would not be large enough to be visible externally.

===Auscultation===
Auscultation of the abdomen, usually performed in a four quadrant approach, can be a useful tool. Auscultation of the ventral abdomen can also be useful in regions where sand impaction is common. Increased gut sounds are not usually found with major changes, and may be indicative of spasmodic colic, or impending diarrhea. A decreased amount of sound, or no sound, may be suggestive of serious changes. Trapped gas, particularly in the caecum, can often be heard by "pinging", where a flick of the finger against the skin over the affected area causes a sharp sound audible through the stethoscope. This sound is sometimes compared to the ringing sound made by a rubber ball hitting a solid surface.

===Faecal Examination===
The amount of faeces produced, and its character can be helpful, although as changes often occur relatively distant to the anus, changes may not be seen for some time. In areas where sand colic is known to be common, or if the history suggests it may be a possibility, faeces can be examined for the presence of sand, often by immersion in water, or simply by its texture. The presence of diarrhoea is common in sand colic, and can be seen in horses with enteroliths. Otherwise, diarrhoea is usually indicative of a non-surgical condition, although it can be associated with life threatening conditions such as [[salmonellosis]].

===Abdominal Ultrasound===
Ultrasonographic evaluation of the abdomen is extremely useful in characterizing certain components of the disease process. The amount and character of free abdominal fluid can be determined, as well as the determination of a specific place for safe, high-yield abdominocentesis. The appearance of small intestine, including distension, wall thickness and motility (or lack thereof, often seen as sedimentatioon of digesta) can be extremely important in the decision for surgical or medical therapy. The large colon and cecum can be evaluated for wall thickness (particularly useful in cases of right dorsal colitis), fluidy contents (colitis/diarrhea), and sometimes displacement. The presence of mesenteric vessels associated with the large colon is generally associated with displacement. The normal anti-mesenteric vessels of the cecum can be used to trace its course. Ventral displacement of the spleen with obscuring of the left kidney is associated with nephro-splenic displacement. Visualization of sacculated large bowel immediately ventral to the liver or spleen, or non-sacculated large bowel in the ventral abdomen suggests displacement. The stomach can be evaluated for distension and abnormalities of the wall. Abdominal ultrasound is useful in detecting diaphragmatic or inguinal herniation. Abnormalities of the liver or kidneys, both potential causes of false colic, are often detectable with ultrasound.

==Clinical signs==
*Pawing and/or scraping
*Stretching
*Frequent attempts to urinate
*Flank watching
*Pacing
*Repeated [[flehmen]] response
*Repeated lying down and rising
*Rolling
*Groaning
*[[Bruxism]]
*Excess salivation
*Inappetance
*Decreased faecal output
*Increased pulse rate
*Dark mucous membranes

==Medical Treatment==

==Surgical Treatment==

==Post-surgical Management==

==Prevention==

==Epidemiology==

===Incidence===
Colic occurs relatively frequently in horses, with an incidence estimated at 0.1-0.2 episodes per horse-year. In context, this would mean an average holding of 100 horses could reasonably expect to see 10-20 cases every year.

===Classification===
Approximately 90% of colic episodes can be succesfully managed using medical treatments, with the remainder requiring surgery. Assuming surgical and medical cases of colic are accurately distinguished, survival rates of 95% and 80% are considered normal for medical and surgical colic, respectively.

===Post-operative Survival===
Studies have shown that there is an increased risk of death with certain factors:
*Abnormal [[hematocrit|Packed Cell Volume]] (PCV) on presentation
*Increased length of intestine resected
*Increased duration of surgery
*Elevated peripheral lactate

==See Also==
*[[equine anatomy#Digestive system|Equine gastrointestinal anatomy]]
*[[Equine nutrition]]

==Further Reading==

==References==
{{reflist}}

Benzodiazepines

2009-04-03T08:36:39Z

Alsiola: /* Side Effects and Contraindications */

Benzodiazepines are primarily anxiolytics, but do have sedative effects in man and sick animals. They also cause muscle relaxation and are anticonvulsants.

==Mechanism of Action==

GABA is an inhibitory neurotransmitter that opens post-synaptic Cl- channel to hyperpolarise the membrane and reduce the chance of action potential conduction occuring. Benzodiazepines modulate the GABA/Cl- channel complexes to enhance the effects of GABA. Benzodiazepines therefore have no intrinsic activity.

==Side Effects and Contraindications==

Benzodiazepines give mild respiratory and cardiovascular suppression. They are however synergistic with central depressants such as barbiturates, antihistamines and alcohol. When administered to healthy animals, they can often act to increase levels of excitement, due to a disinhibition phenomenon.

==Drugs in this Group==

===Diazepam===

Diazepam (Valium) gives a variable degree of sedation. It is a muscle relaxant and therefore should not be used as a sedative in horses. It is also an anticonvulsant, and is used to control status epilepticus. Diazepam also stimulates appetite.

Diazepam may be given orally or intravenously. Intravenous administration gives a rapid onset of action. The drug is dissolved in propylene glycol, which may cause thrombophlebitis, pain on injection and cardiac arrhythmias.

As there are few cardiovascular side effect, diazepam is good for use as a premedicant. It can also be used with [[NMDA Antagonists|ketamine]] to induce and maintain anaethesia in the horse and in compromised small animals.

===Midazolam===

Midazolam is similar to diazepam. It can be give i/m, i/v or orally, and is rapidly metabolised.

==Benzodiazepine Antagonists==

Benzodiazepine antagonists have no intrinsic efficacy, but prevent agonist interaction with receptors. Examples include flumazenil, which is used in man following benzodiazepine overdose.

==Inverse Agonists==

Inverse agonists act at the GABA receptor to close Cl- channels. They promote convulsions.

Talk:Colic

2009-04-03T08:34:03Z

Alsiola: New page: Thought I would get something started on this page. This was something I was working on for wikipedia's colic article, but never got round to finishing. Incomplete and unreferenced, but ...

Thought I would get something started on this page. This was something I was working on for wikipedia's colic article, but never got round to finishing. Incomplete and unreferenced, but hopefully a good start. [[User:Alsiola|Alsiola]] 08:34, 3 April 2009 (UTC)

Colic

2009-04-03T08:32:27Z

Alsiola:

{{unfinished}}
{{horse}}

'''Colic in [[horse]]s''' is defined as [[abdominal pain]], and can be caused by a wide variety of conditions. Many of these conditions are life threatening, and therefore it is essential to diagnose and treat cases of colic as quickly as possible. The most common causes of colic are [[Gastrointestinal tract|gastrointestinal]] conditions, although it can also be caused by other abdominal conditions. In the latter case, it is often called false colic. Treatment of colic is largely dependent upon identifying the underlying reason for the pain, and treating this cause appropriately. Most commonly this is done [[medicine|medically]]{{cn}}, but in a small percentage of cases, [[surgery|surgical intervention]] is needed.{{cn}} Among [[domesticated]] horses, colic is a major cause of premature death.{{cn}} The incidence of colic in the general horse population has been estimated between 10 and 20 percent on an annual basis{{cn}}. It is important that any person who owns or works with horses be able to recognize the signs of colic, so that a [[veterinarian]] may be called promptly.

==Pathophysiology==
This can be divided broadly into simple obstructions, strangulating obstructions, and non-strangulating [[infarctions]].

===Simple Obstruction===
This is characterised by a physical obstruction of the intestine, which can be due to impacted food material, [[stricture]] formation, or foreign bodies. The primary pathophysiological abnormality caused by this obstruction is related to the trapping of fluid within the intestine oral to the obstruction. This is due to the large amount of fluid produced in the upper gastro-intestinal tract (around 125L daily), and the fact that this is primarily re-absorbed in parts of the intestine downstream from the obstruction.
The first problem with this degree of fluid loss from circulation is one of decreased plasma volume, leading to a reduced [[cardiac output]], and [[acid-base imbalance|acid-base disturbances]].

There also occur serious effects on the intestine itself, which becomes distended due to the trapped fluid, and by gas production from bacteria. It is this distension, and subsequent activation of [[Stretch receptor|stretch receptors]] within the intestinal wall, that leads to the associated pain. With progressive distension of the intestinal wall, there is occlusion of blood vessels, firstly veins, then arteries. The difference in time to onset of occlusion is due to the relatively more rigid walls of arteries compared with veins. This impairment of blood supply leads firstly to [[hyperaemia]] and congestion, and ultimately to [[ischaemic]] [[necrosis]] and [[cellular death]]. The poor blood supply also has effects on the vascular endothelium, leading to an increased permeability. This results initially in leakage of [[plasma]], and eventually blood into the intestinal lumen. In the opposite fashion, [[gram-negative]] bacteria and [[endotoxin]]s can enter the bloodstream, leading to further systemic effects.

===Strangulating Infarction===
Strangulating infarctions have all the same pathological features as a simple obstruction, but the bloody supply is immediately affected. Both arteries and veins may be effected immediately, or progressively as in simple obstruction. Common causes of strangulating obstruction are pedunculated lipomas, and displacement of intestine through a hole, such as a [[hernia]], a mesenteric rent, or the [[epiploic foramen]].

===Non-strangulating Infarction===
In a non-strangulating infarction, blood supply to a section of intestine is occluded, without any obstruction to ingesta present within the intestinal lumen. The most common cause is infection with ''Strongylus vulgaris'' larvae, which develop within the (primarily cranial) [[mesenteric artery]].

==Classification==
===Medical Conditions===
====Stomach====
=====Food engorgement=====
This is a life threatening condition, with a great risk of gastric rupture, and also of secondary [[laminitis]]. It is caused by excess food intake, for example, a horse that has broken into a food store.{{cn}}

=====Gastric/pyloric spasm=====
This commonly affects racehorses, immediately after racing, and is known colloquially as 'racehorse colic'. Typically, the animal will have had access to cold water, but this is not always the case. Although the signs of colic seen may be very violent, this condition is not associated with any risk of gastric rupture. [[Spasmolytic]] drugs are ineffective in treatment, however, naso-gastric intubation is immediately curative.{{cn}}
=====Inappropriate feed/poor [[mastication]]=====
Either of these may lead to a condition where the stomach is unable to efficiently empty. A common example is feeding of unsoaked [[sugar beet]], which then expands within the stomach.{{cn}}

=====Neurological [[atony]]=====
A [[chronic]] motility dysfunction, leading to a slow filling of the stomach with [[ingesta]]. Inhibition of gastric outflow is not normally a feature, and therefore gastric rupture is not a risk. A mild colic may be seen, but far more common is poor condition and reduced performance. [[Warmblood]] horses are more commonly affected than other breeds{{cn}}, leading to the suggestion that there may be a genetic component to the disorder. {{cn}}

=====[[Ulceration]]=====
[[Image:Benign_gastric_ulcer_1.jpg‎|thumb|right|A benign gastric ulcer]]
Equine Gastric Ulcer Syndrome (EGUS) is a common cause of mild to moderate colic, and is more prevalent than had been appreciated. In racehorses, the prevalence is as high as 90%. In other performance horses, prevalence ranges from 40-60%. In foals, prevalence is approximately 25%, and probably higher in those being hospitalized for other reasons.{{cn}}

In adult horses, ulceration commonly occurs in the non-glandular portion of the stomach, unlike in humans, where [[peptic ulcers]] are far more common. While the bacterium ''Helicobacter pylori'' is a common cause of ulcers in humans, equine gastric ulcers are not typically infectious in origin. It is thought that EGUS is often stress-related, such as after travelling or confinement, and gastric ulceration is a known potential side-effect of treatment with [[non-steroidal anti-inflammatory drugs|non-steroidal anti-inflammatory drugs]]. A diet consisting of a high proportion of concentrates is also considered a risk factor. In affected horses, pain is often associated with eating, and the horse typically takes one or two bites of food, then no more. A definitive diagnosis requires [[endoscopy]]. Treatment is usually effected using [[H2 antagonist|H2 receptor antagonists]], such as [[Cimetidine]], or [[proton pump inhibitors]], such as [[Omeprazole]].{{cn}}

=====[[Neoplasia]]=====
A [[malignant]] [[squamous]] [[carcinoma]] can effect the [[cardia]] and upper squamous regions of the stomach, resulting in a persistent mild colic, commonly seen soon after feeding. Weight loss and general ill health are usually seen, and the prognosis is very poor, due to the high risk of [[metastasis]].
====Small Intestine====
=====Spasmodic colic=====
Spasmodic colic accounts for a large proportion of colic cases seen in first-opinion practice, however, little is known about its causes. It generally produces a mild colic, due to increased [[peristaltis|peristaltic]] activity in the gastro-intestinal tract. Cases are usually easily resolved by treating with a [[spasmolytic]] such as [[Buscopan]], and a mild [[analgesic]] such as [[phenylbutazone]].
=====[[Grass sickness]]=====
Equine grass sickness, or equine [[dysautonomia]] causes a paralysis of the gastro-intestinal tract, by disruption of the [[autonomic nervous system]]. This leads to a pooling of ingesta throughout all parts of the gastro-intestinal tract. The condition may occur acutely, or progress chronically over several weeks, but all cases will eventually die. A definitive diagnosis is obtained by taking an ileal [[biopsy]], and inspecting the intrinsic [[myenteric plexus]]. There is no effective treatment, although in the short to medium term, horses can be successfully managed by informed and attentive owners.

====Caecum====
=====Flatulent colic=====
Flatulent, or gas colic, occurs when caecal gases are produced faster than they can be removed by the caecum and colon, leading to a distension of the caecum. A diagnosis is strongly confirmed by a right sided abdominal distension, and [[auscultation]]/percussion of tympanitic sounds. Treatment involves withdrawal of fluid, and intra-venous fluid therapy. The distension can be relieved by [[trocharisation]] of the caecal head, via the right sub-lumbar fossa, which is ideally performed using ultrasound guidance.

====Large Colon====
=====Pelvic flexure impaction=====
A relatively common form of colic, that is often associated with a recent change in diet, management or exercise levels. Pain is moderate, and often persists despite adequate [[analgesia]], a sign more commonly associated with colic of a surgical nature. However, rectal examination provides a definitive diagnosis, with a large, doughy structure occupying much of the pelvis. Treatment involves encouraging fluid output into the large colon, to help soften the impaction, firstly by ensuring adequate hydration with intra-venous fluids, and sometimes by administration of [[sodium chloride]] and sodium sulphate orally, to create an [[osmotic]] gradient. Large volumes of water, sometimes with Magnesium Sulfate with or without liquid paraffin ([[Mineral oil]]) are also given by naso-gastric tube, to help soften the impaction and encourage its movement.

=====Left dorsal displacement=====
Left dorsal displacement, or nephrosplenic entrapment, is a frequent cause of colic, where the left dorsal and ventral colon become displaced, and then trapped by the [[spleen]] laterally, the [[kidney]] medially, and the [[nephrosplenic ligament]] ventrally. It can be diagnosed by rectal examination. The first line of treatment is intra-venous [[phenylephrine]] injection, which acts to contract the spleen, so helping release the trapped colon. This is often combined with gentle exercise to encourage movement of the abdominal contents. Circling on the left rein is considered particularly helpful, as it increases the potential space between the spleen and the body wall, allowing more room for the colon to return to its normal location. If this fails, then general anaesthesia is needed. Replacement of the colon is then attempted by rolling of the horse. If this also fails then surgery is needed to correct the displacement.

====Small Colon====
=====Pelvic masses=====
A persistent mild colic may be found when intra-pelvic masses impinge upon the gastro-intestinal tract. Most commonly these are haematomas. Peri-anal lesions, such as [[melanomas]] may also produce these signs.

=====Neurological deficits=====
A complete or partial paralysis of the small colon and rectum may occur with [[polyneuritis equi]], resulting in a lack of faecal expulsion, and consequent obstruction. A diagnosis is made via a neurological examination. Treatment is palliative only, although the condition can be managed for many years by manual emptying of the rectum.

===Surgical Conditions===
====Small Intestine====
=====Impaction=====
Association with ascarid infection<ref>Cribb NC, Cote NM, Bouré LP, Peregrine AS. (2006). ''Acute small intestinal obstruction associated with Parascaris equorum infection in young horses: 25 cases (1985-2004).''. New Zealand Veterinary Journal</ref>

=====Intussusception=====
=====Herniation/entrapment=====
*Inguinal canal
*Umbilical hernia
*Epiploic foramen
*Mesenteric rents/tears
*Diaphragmatic hernia
*Mesodiverticular bands
*Gastrosplenic ligament

=====Pedunculated lipoma=====
=====Volvulus (nodosus)=====
=====Rotation of mesenteric root=====
====Caecum====
=====Caeco-caecal intussusception=====
=====Torsion=====
=====Impaction=====
====Large Colon====
=====Torsion=====
=====Left dorsal displacement=====
=====Right dorsal displacement=====

=====Sand impaction=====

=====Enterolith=====

====Small Colon====
=====Faecolith=====

=====Enterolith=====

=====Strangulating lipoma=====

====Any location====
=====Foreign body=====
===False colic===
Signs of colic may be caused by abdominal pain not associated with the gastro-intestinal tract, for example, pain associated with uterine or [[testis|testicular]] torsion, or originating from the [[kidney]]s, [[liver]], [[ovary|ovaries]], spleen, [[pleuritis]], or pleuropneumonia. Other diseases which sometimes cause symptoms which appear similar to colic include [[laminitis]] and [[Equine Exertional Rhabdomyolysis|exertional rhabdomyolysis]].

==Diagnosis==
Many different diagnostic tests can be used to diagnose the cause of equine colic, which may have greater or lesser value in certain situations. The most important distinction to make is whether the condition should be managed medically or surgically. If surgery is indicated, then it must be performed with utmost haste, as delay is a dire prognostic indicator.

===History===
A thorough history is always taken, including age, sex, recent activity, diet, any recent dietary changes, and routine anthelmintic treatment. However, the most important factor is time elapsed since onset of clinical signs, as this has a profound impact on prognosis, and the type of treatment that will be undertaken.

===Cardiovascular Parameters===
Heart rate rises with progression of colic, in part due to pain, but mainly due to decreased circulating volume, decreased [[preload]], and [[endotoxemia]]. The rate should be measured over time, and its response to analgesic therapy ascertained. A pulse that continues to rise in the face of adequate analgesia is considered a surgical indication.
[[Mucous membrane]] colour can be assessed to appreciate the severity of haemodynamic compromise. Reddening of membranes reflects worse prognosis, and [[cyanotic]] membranes indicate a very poor chance of a positive outcome.

Laboratory tests can be performed to assess the cardiovascular status of the patient. [[Packed Cell Volume]] (PCV) is a measure of hydration status, with a value 45% being considered significant. Increasing values over repeated examination are also considered significant. The total protein (TP) of blood may also be measured, as an aid in estimating the amount of protein loss into the intestine. Its value must be interpreted along with the PCV, to take into account the hydration status. Blood lactate levels are useful in determining severity of disease, and as a prognostic indicator; levels between 1-2mmol/L are considered normal, while levels above 5.7mmol/L are considered significant. "Colic scores" that combine several parameters can be relatively accurate prognostic indicators, although most laboratory tests have limited use in terms of specific diagnosis.

===Rectal Examination===
Repeated rectal examinations are a cornerstone of colic diagnosis, as many large intestinal conditions can be definitively diagnosed by this method alone. Other non-specific findings, such as dilated small intestinal loops, may also be detected, and can play a major part in determining if surgery is necessary.

===Naso-gastric Intubation===
Passing a Naso-Gastric Tube (NGT) is useful both diagnostically and therapeutically. Fluid is refluxed from the stomach, and any more than 2 litres of fluid is considered to be significant. Increased fluid is generally a result of backing up of fluid through the intestinal tract, due to a downstream obstruction. This finding is important as it represents a relatively advanced stage of colic, and is often a surgical indication. Therapeutically, gastric decompression is important, since horses are unable to vomit. If fluid build up occurs, gastric rupture may occur, which is inevitably fatal.

===Abdominocentesis===
The extraction of fluid from the peritoneum can be useful in assessing the state of the intestines. A [[sanguinous]] fluid can be caused by an [[infarction]], which indicates surgery is necessary. However, sanguinous fluid can also be caused by external trauma (e.g. rib fractures), middle uterine artery rupture in post-foaling mares, or by inadvertent bleeding caused by the procedure itself. A cloudy fluid is suggestive of an increased number of white blood cells, which indicates the disease is relatively advanced. The protein level of abdominal fluid can be analysed, and may also give information as to the integrity of intestinal blood vessels. Elevated lactate levels in the sample can also give an indication of the degree of compromise to bowel, particularly as a peritoneal:peripheral lactate ratio. Peritoneal fluid that contains food material can indicate rupture of the gastro-intestinal tract, although care should be taken that intestine has not been punctured inadvertently.
A normal peritoneal fluid sample does not rule out a strangulating lesion. For example, in the case of a diaphragmatic hernia, the strangulating gut is contained within the thoracic cavity, so will not affect fluid within the abdominal cavity. A similar situation is true of intussuception, where the strangulating gut is contained with another piece of non-strangulating gut.

===Abdominal Distension===
Any degree of abdominal distension is usually indicative of a condition affecting the large intestines, as distension of structures upstream of here would not be large enough to be visible externally.

===Auscultation===
Auscultation of the abdomen, usually performed in a four quadrant approach, can be a useful tool. Auscultation of the ventral abdomen can also be useful in regions where sand impaction is common. Increased gut sounds are not usually found with major changes, and may be indicative of spasmodic colic, or impending diarrhea. A decreased amount of sound, or no sound, may be suggestive of serious changes. Trapped gas, particularly in the caecum, can often be heard by "pinging", where a flick of the finger against the skin over the affected area causes a sharp sound audible through the stethoscope. This sound is sometimes compared to the ringing sound made by a rubber ball hitting a solid surface.

===Faecal Examination===
The amount of faeces produced, and its character can be helpful, although as changes often occur relatively distant to the anus, changes may not be seen for some time. In areas where sand colic is known to be common, or if the history suggests it may be a possibility, faeces can be examined for the presence of sand, often by immersion in water, or simply by its texture. The presence of diarrhoea is common in sand colic, and can be seen in horses with enteroliths. Otherwise, diarrhoea is usually indicative of a non-surgical condition, although it can be associated with life threatening conditions such as [[salmonellosis]].

===Abdominal Ultrasound===
Ultrasonographic evaluation of the abdomen is extremely useful in characterizing certain components of the disease process. The amount and character of free abdominal fluid can be determined, as well as the determination of a specific place for safe, high-yield abdominocentesis. The appearance of small intestine, including distension, wall thickness and motility (or lack thereof, often seen as sedimentatioon of digesta) can be extremely important in the decision for surgical or medical therapy. The large colon and cecum can be evaluated for wall thickness (particularly useful in cases of right dorsal colitis), fluidy contents (colitis/diarrhea), and sometimes displacement. The presence of mesenteric vessels associated with the large colon is generally associated with displacement. The normal anti-mesenteric vessels of the cecum can be used to trace its course. Ventral displacement of the spleen with obscuring of the left kidney is associated with nephro-splenic displacement. Visualization of sacculated large bowel immediately ventral to the liver or spleen, or non-sacculated large bowel in the ventral abdomen suggests displacement. The stomach can be evaluated for distension and abnormalities of the wall. Abdominal ultrasound is useful in detecting diaphragmatic or inguinal herniation. Abnormalities of the liver or kidneys, both potential causes of false colic, are often detectable with ultrasound.

==Clinical signs==
*Pawing and/or scraping
*Stretching
*Frequent attempts to urinate
*Flank watching
*Pacing
*Repeated [[flehmen]] response
*Repeated lying down and rising
*Rolling
*Groaning
*[[Bruxism]]
*Excess salivation
*Inappetance
*Decreased faecal output
*Increased pulse rate
*Dark mucous membranes

==Medical Treatment==

==Surgical Treatment==

==Post-surgical Management==

==Prevention==

==Epidemiology==

===Incidence===
Colic occurs relatively frequently in horses, with an incidence estimated at 0.1-0.2 episodes per horse-year.{{cn}} In context, this would mean an average holding of 100 horses could reasonably expect to see 10-20 cases every year.

===Classification===
Approximately 90% of colic episodes can be succesfully managed using medical treatments, with the remainder requiring surgery.{{cn}} Assuming surgical and medical cases of colic are accurately distinguished, survival rates of 95% and 80% are considered normal for medical and surgical colic, respectively.{{cn}}

===Post-operative Survival===
Studies have shown that there is an increased risk of death with certain factors{{cn}}:
*Abnormal [[hematocrit|Packed Cell Volume]] (PCV) on presentation
*Increased length of intestine resected
*Increased duration of surgery
*Elevated peripheral lactate

==See Also==
*[[equine anatomy#Digestive system|Equine gastrointestinal anatomy]]
*[[Equine nutrition]]

==Further Reading==

==References==
{{reflist}}