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[[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>]]

| Also known as:

| Also known as:

| '''Blackquarter

| '''Blackquarter

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==Description==  

==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.  

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.

 

==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.

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.

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 including the tongue or diaphram. 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 on smears produced from the primary lesion.

Diagnosis is made on clinical signs and muscle biopsy.  

==History and Clinical Signs==

==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, [[Lungs Circulatory - Pathology#Pulmonary oedema|pulmonary oedema]], circulatory collapse lameness and swollen hot muscles which later become cool as necrosis occurs.

The bacteria can cause rapid toxaemia resulting in sudden 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==

In the early stages the periphery of the muscle appears dark red and is distended by serous or serosanguinous exudate. Is wet on the cut surface with a rancid smell. The center of the lesion is full of gas bubbles, porous, dry and reddish black.  

 

In the early stages the periphery of the muscle appears dark red and is distended by serous or serosanguinous exudate. <fint color ='red'  WHAT Is wet on the cut surface with a rancid smell.</font color> The center of the lesion is full of gas bubbles, porous, dry and reddish black.  

Additionally gram positive bacteria may be found in clumps.

Additionally gram positive bacteria may be found in clumps.

==Prognosis==

==Prognosis==

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

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

==References==

==References==

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

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

[[Category:Sheep]][[Category:Cattle]][[Category:To_Do_-_Review]]

[[Category:Sheep]][[Category:Cattle]]

[[Category:To_Do_-_Caz]]

[[Category:To_Do_-_Caz]]