Changes

==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 swellings of the muscles.  

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 affeceted particularly animals in good health and gaining weight quickly. 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 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, blackleg infection is endogenous, in contrast to malignant edema ( Malignant Edema). Lesions develop without any history of wounds, although bruising or excessive exercise may precipitate some cases. Commonly, the animals that contract blackleg are of the beef breeds, in excellent health, gaining weight, and usually the best animals of their group. Outbreaks occur in which a few new cases are found each day for several days. Most cases are seen in cattle from 6-24 mo old, but thrifty calves as young as 6 wk and cattle as old as 10-12 yr may be affected. The disease usually occurs in summer and fall and is uncommon during the winter. In sheep, the disease is not restricted to the young, and most cases follow some form of injury such as shearing cuts, docking, crutching, or castration. Endogenous blackleg in sheep is uncommon in the USA; it is much more common in New Zealand where blackleg is seen more frequently in sheep than in cattle.  

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

==Diagnosis==

==Diagnosis==

==History and Clinical Signs==

==History and Clinical Signs==

 

 

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 later becoming cool as necrosis occurs.

*May affect the fattest cattle at pasture in the summer

*Rapid toxaemia -> death

*If clinical signs observed:

**Toxaemia -> pyrexia, depression, [[Lungs Circulatory - Pathology#Pulmonary oedema|pulmonary oedema]], circulatory collapse

**Muscle lesions -> lameness, swollen hot muscles later becoming cool as necrosis sets in

*Pathogenesis:

*Pathogenesis:

**Spores gain entry to GI tract -> blood -> muscle -> lie latent  

**Spores gain entry to GI tract -> blood -> muscle -> lie latent. Under right conditions (usually anaerobic following injury) they germinate and bacilli grow. Toxin damages capillaries -> serosanguinous exudate. Muscle necrosis due to gas producing bacteria -> emphysaema and crepitus

**Under right conditions (usually anaerobic following injury) they germinate and bacilli grow

**Toxin damages capillaries -> serosanguinous exudate

**Muscle necrosis due to gas producing bacteria -> emphysaema and crepitus

*Grossly:

*Grossly:

**Early stages

**Early stages