Difference between revisions of "Black Leg"

 
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Also known as: '''''Blackquarter
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==Introduction==
 
[[Image:Black leg myositis.jpg|right|thumb|300px|<small><center>Blackleg myositis (Image sourced from Bristol Biomed Image Archive with permission)</center></small>]]
 
[[Image:Black leg myositis.jpg|right|thumb|300px|<small><center>Blackleg myositis (Image sourced from Bristol Biomed Image Archive with permission)</center></small>]]
 
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A bacterial disease affecting cattle and sheep caused by [[Clostridium chauvoei|''Clostridium chauvoei'']]. Spores pass through the wall of the GI tract and via the bloodstream enter the muscle and liver where they then lie latent. This results in oedematous and crepitant swelling of the muscles. Under the correct conditions (usually anaerobic following injury) they germinate and bacilli grow. Toxins damage the capillaries causing a severe necrotising myositis.
{| cellpadding="10" cellspacing="0" border="1"
 
| Also known as:
 
| '''Blackquarter
 
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==Description==
 
A bacterial disease affecting cattle and sheep caused by [[Clostridium chauvoei|''Clostridium chauvoei'']]. Latent spores of this organism are deposited in the muscle and liver of ruminants via the circulation resulting in oedematous and crepitant swelling of the muscles.  
 
 
 
  
 
==Signalment==
 
==Signalment==
 
In cattle it is typically beef breeds who are affected particularly animals in good health and good body condition. More frequently occurs in cattle between 6-24 months old but can affect animals of any age. In some animals lesions occur following muscle trauma, which is thought to activate latent spores in the muscle.
 
In cattle it is typically beef breeds who are affected particularly animals in good health and good body condition. More frequently occurs in cattle between 6-24 months old but can affect animals of any age. In some animals lesions occur following muscle trauma, which is thought to activate latent spores in the muscle.
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In sheep, cases typically occur following some form of injury such as shearing cuts, docking or castration.
 
In sheep, cases typically occur following some form of injury such as shearing cuts, docking or castration.
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Tends to affect animals in the summer months.
 
Tends to affect animals in the summer months.
  
 
==Diagnosis==
 
==Diagnosis==
Diagnosis is made on clinical signs and muscle biopsy. Affected muscle is black, dry and infiltrated with small bubbles. The lesions can be present in any muscle. Often in sheep, lesions are deep and quite small. Suspected cases can be confirmed using demonstration of ''C. chauvoei'' in affected muscle using the fluorescent antibody test.  
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Diagnosis is made on clinical signs and muscle biopsy.  
  
 
==History and Clinical Signs==
 
==History and Clinical Signs==
 
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The bacteria can cause rapid toxaemia resulting in sudden death, however, if clinical signs do occur these can include toxaemia, pyrexia, depression, [[Pulmonary Oedema|pulmonary oedema]], circulatory collapse lameness and swollen hot muscles which later become cool as necrosis occurs.
Spores pass through the wall of the GI tract and via the bloodstream enter the muscle where they then lie latent. Under the correct conditions (usually anaerobic following injury) they germinate and bacilli grow. Toxins damage the capillaries causing a serosanguinous exudate. Muscle necrosis occurs due to gas producing bacteria resulting in emphysaema and crepitus
 
The bacteria can cause rapid toxaemia resulting in death, however if clinical signs do occur these can include toxaemia, pyrexia, depression, [[Lungs Circulatory - Pathology#Pulmonary oedema|pulmonary oedema]], circulatory collapse lameness and swollen hot muscles which later become cool as necrosis occurs.
 
  
 
==Pathology==
 
==Pathology==
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Affected muscle is black, dry, infiltrated with small bubbles, distended by serous or serosanguinous exudate and often has a rancid smell. The lesions can be present in any muscle including the tongue or diaphragm and it is not unusual to find clumps of gram positive bacteria in affected muscle. Often in sheep, lesions are deep and quite small. Suspected cases can be confirmed using demonstration of ''C. chauvoei'' in diseased muscle using the fluorescent antibody test on smears produced from the primary lesion.
  
In the early stages the musce periphery appears dark red and is Distended by serous or serosanguinous exudate. Is wet on the cut surface
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==Treatment==
and the centre of the lesion is full of gas bubbles, porous, dry, reddish black
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Vaccination can prevent black leg in cattle and sheep. In the face of an outbreak all susceptible animals should be treated with penicillin and vaccinated.
***Rancid odour
 
*Histologically:
 
In the early stages separation of the myofibres by exudate can be seen which progresses to [[Necrosis - Pathology#Coagulation Necrosis|Coagulative necrosis]] No nuclei
 
**Old stage
 
***Fragmented muscle fibres separated by gas bubbles
 
***Gram positive bacilli may be found in clumps
 
[[Category:Sheep]][[Category:To_Do_-_Caz]]
 
  
==Treatment==
 
 
==Prognosis==
 
==Prognosis==
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Poor, clinical cases can be treated with penicillin however this is rarely successful.
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==Literature Search==
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[[File:CABI logo.jpg|left|90px]]
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Use these links to find recent scientific publications via CAB Abstracts (log in required unless accessing from a subscribing organisation).
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<br><br><br>
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[http://www.cabdirect.org/search.html?q=%28%28title%3A%28%22Clostridium+chauvoei%22%29+AND+sc%3A%22ve%22%29%29+OR+%28%28title%3A%28%22blackleg%22%29+OR+title%3A%28%22black+leg%22%29+OR+title%3A%28%22black+quarter%22%29+OR+title%3A%28%22blackquarter%22%29+AND+sc%3A%22ve%22%29%29 Blackleg publications]
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==References==
 
==References==
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Merck & Co (2008) '''The Merck Veterinary Manual''' (Eighth Edition) Merial
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{{review}}
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[[Category:Musculoskeletal Diseases - Sheep]][[Category:Liver Diseases - Sheep]][[Category:Musculoskeletal Diseases - Cattle]][[Category:Liver Diseases - Cattle]][[Category:Bacterial Myositis]]
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[[Category:Brian Aldridge reviewing]]

Latest revision as of 14:17, 6 May 2011

Also known as: Blackquarter

Introduction

Blackleg myositis (Image sourced from Bristol Biomed Image Archive with permission)

A bacterial disease affecting cattle and sheep caused by Clostridium chauvoei. Spores pass through the wall of the GI tract and via the bloodstream enter the muscle and liver where they then lie latent. This results in oedematous and crepitant swelling of the muscles. Under the correct conditions (usually anaerobic following injury) they germinate and bacilli grow. Toxins damage the capillaries causing a severe necrotising myositis.

Signalment

In cattle it is typically beef breeds who are affected particularly animals in good health and good body condition. More frequently occurs in cattle between 6-24 months old but can affect animals of any age. In some animals lesions occur following muscle trauma, which is thought to activate latent spores in the muscle.

In sheep, cases typically occur following some form of injury such as shearing cuts, docking or castration.

Tends to affect animals in the summer months.

Diagnosis

Diagnosis is made on clinical signs and muscle biopsy.

History and Clinical Signs

The bacteria can cause rapid toxaemia resulting in sudden death, however, if clinical signs do occur these can include toxaemia, pyrexia, depression, pulmonary oedema, circulatory collapse lameness and swollen hot muscles which later become cool as necrosis occurs.

Pathology

Affected muscle is black, dry, infiltrated with small bubbles, distended by serous or serosanguinous exudate and often has a rancid smell. The lesions can be present in any muscle including the tongue or diaphragm and it is not unusual to find clumps of gram positive bacteria in affected muscle. Often in sheep, lesions are deep and quite small. Suspected cases can be confirmed using demonstration of C. chauvoei in diseased muscle using the fluorescent antibody test on smears produced from the primary lesion.

Treatment

Vaccination can prevent black leg in cattle and sheep. In the face of an outbreak all susceptible animals should be treated with penicillin and vaccinated.

Prognosis

Poor, clinical cases can be treated with penicillin however this is rarely successful.

Literature Search

CABI logo.jpg


Use these links to find recent scientific publications via CAB Abstracts (log in required unless accessing from a subscribing organisation).


Blackleg publications

References

Merck & Co (2008) The Merck Veterinary Manual (Eighth Edition) Merial