Systematic Veterinary Bacteriology and Mycology

PATHOGENECITY

Symptoms

• The disease usually occurs in young cattle of 6 months to about 2-3 years of age.
• The most obvious sign is crepitating swelling particularly in the hind or fore quarter which rackels when rubbed with the fingers as a result of gas production.

• The affected animal will become lame and the affected muscles shows trembling with violent twitching. Death usually occurs within 24 hours.
• In sheep an acute febrile condition develops within 1-2 days following an injury and a typical black quarter lesion can be observed at the site. Death occurs suddenly

Lesion

• In the central part of the lesion there is usually a well-defined area of muscle, which is dark red in colour, dry, necrotic and filled with small gas bubbles, which give a swollen appearance to the muscles.
• The lesion has a characteristic rancid odour. Surrounded this area of muscle there will be yellowish or blood stained oedematous fluid.
• In ewes there will be necrosis of the vaginal mucosa and skin with extensive oedema involving the hind limbs and thigh muscles.