Author, Donkey, Bureaucrats, Administrators
53,803
edits
Changes
Jump to navigation
Jump to search
Category:Forestomach - Nutritional Pathology (view source)
Revision as of 14:35, 28 May 2010
, 14:35, 28 May 2010Created page with '==Bloat/Tympany== * When eructation fails, the rumen becomes distended due to the accumulation of gas …'
==Bloat/Tympany==
* When [[Eructation - Anatomy & Physiology|eructation]] fails, the [[The Rumen - Anatomy & Physiology|rumen]] becomes distended due to the accumulation of gas produced by the fermentation process. This distension is known as '''bloat''' or '''tympany'''.
===Clinical===
*The disease is acute and progressive and will result in death in a matter of hours.
===Pathology===
* In severe bloating, that the [[The Rumen - Anatomy & Physiology|rumen]] almost fills the abdomen.
** Diaphragm is displaced forwards, compressing the lungs.
** Posterior vena cava (lying dorsally) is also compressed, reducing the venous return to the heart.
** Respiration is depressed and animals die from anoxia.[[Image:oesophageal bloat line.jpg|thumb|right|150px|Oesophageal "bloat line" (Courtesy of Elspeth Milne)]]
*** Blood is dark (hypoxic) and clots poorly.
* The anterior parts of the body are often characteristically acutely congested.
** Oedema and subcutaneous haemorrhage of head and neck tissues.
** [[Oesophagus - Anatomy & Physiology|Oesophageal]] "bloat line" at thoracic inlet.
*** Congested and haemorrhagic cranially, pale caudally.
===Pathogenesis===
* There are two forms of bloat:
** '''Frothy bloat/ Primary bloat'''
*** Occurs following ingestion of large amounts of succulent green plant material. This is highly fermentable and produces large amounts of gas.
*** Material contains high levels of soluble proteins. These act as foaming agents by reducing surface tension but increasing surface viscosity of rumenal liquids and a stable rumenal foam forms.
*** The [[Volatile Fatty Acids - Anatomy & Physioogy|volatile fatty acids]] of the plant material consumed lower pH, optimising conditions for formation of froth.
*** Gas present in bubble form is insufficient to trigger eructation, and so the [[The Rumen - Anatomy & Physiology|rumen]] becomes distended.
** '''Free gas bloat/ Secondary bloat'''
*** May be:
**** '''Acute'''
*****Due to sudden [[Oesophagus - Anatomy & Physiology|oesophageal]] obstruction, for example by a solid foreign body (e.g. a piece of potato or turnip).
**** '''Chronic'''
***** Results from partial [[Oesophagus - Anatomy & Physiology|oesophageal]] obstruction/ compression, or from interference with the normal eructation mechanism, e.g. with:
****** partially obstructive foreign bodies
****** actinobacillosis in the oesophagus or [[Oesophageal groove|oesophageal groove]]
****** [[Oesophagus - Anatomy & Physiology|oesophagus]] or groove tumours
****** chronic inflammatory or adhesive disease of the [[The Reticulum - Anatomy & Physiology|reticulum]]
***** Some passage of gas is possible, so gas build-up and distenesion is more prolonged.
***** Interference with cardiac and respiratory function is seldom life threatening.
==Rumenal Acidosis==
* Like bloat, rumenal acidosis is associated with mismanagement of feeding and involves cessation or depression of [[Rumination - Anatomy & Physiology|rumenal movements]] with development of a degree of tympany.
* More common in cattle and goats than in sheep due to differences in diet.
===Clinical===
* Animals display signs of abdominal discomfort, but usually recover if treated.
* Acute disease can result in death if acidosis is severe.
===Pathogenesis===
* Occurs following feeding of highly fermentable material, usually carbohydrate, in the form of concentrate or cereal
** e.g. in barley beef feeding systems.
* An overgrowth of Gram positive bacteria results, breaking carbohydrate down very quickly.
** Increased [[Volatile Fatty Acids - Anatomy & Physioogy|volatile fatty acid]] production decreases the [[The Rumen - Anatomy & Physiology|rumen]] pH to about 5.
*** [[The Rumen - Anatomy & Physiology|Rumen]] epithelium is damaged- ruminitis.
*** Osmotic effects of [[The Rumen - Anatomy & Physiology|rumen]] contents produce severe dehydration.
*** Death may ensue when the [[The Rumen - Anatomy & Physiology|rumen]] pH drops to 4.5 or below.
* Normal flora may invade the damaged wall of [[The Rumen - Anatomy & Physiology|rumen]] e.g. Fusiformis necrophorum.
** Results in areas with mushy necrotic papillae.
** Especially on pillars and ventral parts of [[The Rumen - Anatomy & Physiology|rumen]].
* Excess gas production may occur
** Concentrate does not contain soluble proteins, therefore foam does not develop.
** Only mild to moderate free gas bloat is likely- much of the rumenal distension which occurs with rumenal acidosis is due to fluid sequestration in the [[The Rumen - Anatomy & Physiology|rumen]].
===Pathology===
====Gross====
* Gross PM findings may be non-specific.
* Ruminal stasis/bloat leads to rumen distension
* [[The Rumen - Anatomy & Physiology|Rumen]] contents are porridge-like.
* Rumenitis may be present
** Normal flora invading wall of rumen may enter blood as thromboemboli and travel in the portal flow to [[Liver - Anatomy & Physiology|liver]]
** Focal abscesses are produced, which heal with sunken star-shaped scars.
* Overgrowth of Clostridia may cause endotoxic shock with widespread petechial haemorrhages.
====Histological====
* Microvesicles may be present in the epithelium of the [[The Rumen - Anatomy & Physiology|rumen]] papillae.
** Contain mainly [[Neutrophils - WikiBlood|neutrophils]]
* May be focal erosions/ulceration.
===Sequelae===
* Scarring- necrotised papillae are replaced by smooth epithelium closely adherent to sub mucosa.
* Has economic significance since many barley beef livers are condemned at meat inspection.
* More persistent organisms can invade [[The Rumen - Anatomy & Physiology|rumen]] wall producing chronic infection.
** These are often fungi, e.g. Mucor (see [[Forestomach Inflammation - Pathology#Mucormycosis|Mucormycosis]]).
[[Category:Forestomach - Pathology]]
* When [[Eructation - Anatomy & Physiology|eructation]] fails, the [[The Rumen - Anatomy & Physiology|rumen]] becomes distended due to the accumulation of gas produced by the fermentation process. This distension is known as '''bloat''' or '''tympany'''.
===Clinical===
*The disease is acute and progressive and will result in death in a matter of hours.
===Pathology===
* In severe bloating, that the [[The Rumen - Anatomy & Physiology|rumen]] almost fills the abdomen.
** Diaphragm is displaced forwards, compressing the lungs.
** Posterior vena cava (lying dorsally) is also compressed, reducing the venous return to the heart.
** Respiration is depressed and animals die from anoxia.[[Image:oesophageal bloat line.jpg|thumb|right|150px|Oesophageal "bloat line" (Courtesy of Elspeth Milne)]]
*** Blood is dark (hypoxic) and clots poorly.
* The anterior parts of the body are often characteristically acutely congested.
** Oedema and subcutaneous haemorrhage of head and neck tissues.
** [[Oesophagus - Anatomy & Physiology|Oesophageal]] "bloat line" at thoracic inlet.
*** Congested and haemorrhagic cranially, pale caudally.
===Pathogenesis===
* There are two forms of bloat:
** '''Frothy bloat/ Primary bloat'''
*** Occurs following ingestion of large amounts of succulent green plant material. This is highly fermentable and produces large amounts of gas.
*** Material contains high levels of soluble proteins. These act as foaming agents by reducing surface tension but increasing surface viscosity of rumenal liquids and a stable rumenal foam forms.
*** The [[Volatile Fatty Acids - Anatomy & Physioogy|volatile fatty acids]] of the plant material consumed lower pH, optimising conditions for formation of froth.
*** Gas present in bubble form is insufficient to trigger eructation, and so the [[The Rumen - Anatomy & Physiology|rumen]] becomes distended.
** '''Free gas bloat/ Secondary bloat'''
*** May be:
**** '''Acute'''
*****Due to sudden [[Oesophagus - Anatomy & Physiology|oesophageal]] obstruction, for example by a solid foreign body (e.g. a piece of potato or turnip).
**** '''Chronic'''
***** Results from partial [[Oesophagus - Anatomy & Physiology|oesophageal]] obstruction/ compression, or from interference with the normal eructation mechanism, e.g. with:
****** partially obstructive foreign bodies
****** actinobacillosis in the oesophagus or [[Oesophageal groove|oesophageal groove]]
****** [[Oesophagus - Anatomy & Physiology|oesophagus]] or groove tumours
****** chronic inflammatory or adhesive disease of the [[The Reticulum - Anatomy & Physiology|reticulum]]
***** Some passage of gas is possible, so gas build-up and distenesion is more prolonged.
***** Interference with cardiac and respiratory function is seldom life threatening.
==Rumenal Acidosis==
* Like bloat, rumenal acidosis is associated with mismanagement of feeding and involves cessation or depression of [[Rumination - Anatomy & Physiology|rumenal movements]] with development of a degree of tympany.
* More common in cattle and goats than in sheep due to differences in diet.
===Clinical===
* Animals display signs of abdominal discomfort, but usually recover if treated.
* Acute disease can result in death if acidosis is severe.
===Pathogenesis===
* Occurs following feeding of highly fermentable material, usually carbohydrate, in the form of concentrate or cereal
** e.g. in barley beef feeding systems.
* An overgrowth of Gram positive bacteria results, breaking carbohydrate down very quickly.
** Increased [[Volatile Fatty Acids - Anatomy & Physioogy|volatile fatty acid]] production decreases the [[The Rumen - Anatomy & Physiology|rumen]] pH to about 5.
*** [[The Rumen - Anatomy & Physiology|Rumen]] epithelium is damaged- ruminitis.
*** Osmotic effects of [[The Rumen - Anatomy & Physiology|rumen]] contents produce severe dehydration.
*** Death may ensue when the [[The Rumen - Anatomy & Physiology|rumen]] pH drops to 4.5 or below.
* Normal flora may invade the damaged wall of [[The Rumen - Anatomy & Physiology|rumen]] e.g. Fusiformis necrophorum.
** Results in areas with mushy necrotic papillae.
** Especially on pillars and ventral parts of [[The Rumen - Anatomy & Physiology|rumen]].
* Excess gas production may occur
** Concentrate does not contain soluble proteins, therefore foam does not develop.
** Only mild to moderate free gas bloat is likely- much of the rumenal distension which occurs with rumenal acidosis is due to fluid sequestration in the [[The Rumen - Anatomy & Physiology|rumen]].
===Pathology===
====Gross====
* Gross PM findings may be non-specific.
* Ruminal stasis/bloat leads to rumen distension
* [[The Rumen - Anatomy & Physiology|Rumen]] contents are porridge-like.
* Rumenitis may be present
** Normal flora invading wall of rumen may enter blood as thromboemboli and travel in the portal flow to [[Liver - Anatomy & Physiology|liver]]
** Focal abscesses are produced, which heal with sunken star-shaped scars.
* Overgrowth of Clostridia may cause endotoxic shock with widespread petechial haemorrhages.
====Histological====
* Microvesicles may be present in the epithelium of the [[The Rumen - Anatomy & Physiology|rumen]] papillae.
** Contain mainly [[Neutrophils - WikiBlood|neutrophils]]
* May be focal erosions/ulceration.
===Sequelae===
* Scarring- necrotised papillae are replaced by smooth epithelium closely adherent to sub mucosa.
* Has economic significance since many barley beef livers are condemned at meat inspection.
* More persistent organisms can invade [[The Rumen - Anatomy & Physiology|rumen]] wall producing chronic infection.
** These are often fungi, e.g. Mucor (see [[Forestomach Inflammation - Pathology#Mucormycosis|Mucormycosis]]).
[[Category:Forestomach - Pathology]]