Black Quarter

BQ is most commonly caused by Clostridium chauvoei. These are Gram-positive, rod-shaped; anaerobic that can produce environmentally-persistent spores in unfavorable conditions. These spores can remain in the soil for years in an inactive state, and return to their infectious form when consumed by grazing livestock and infect the large muscles of the animal where the bacteria grow and produce large amount of gas. Contaminated pasture is a predominant source of these organisms, which are also found naturally in the intestines of animals. Disease can occur over many years in areas where there is soil or manure contamination with the bacteria, and it is extremely difficult to remove the spores from the environment.

It is seen in livestock all over the world, usually affecting cattle, sheep and goats. It has been seen occasionally in farmed bison and deer.

What symptoms or signs can be seen in affected animals?

Initially animal may develop fever, and the affected limb is hot to touch. The limb swells significantly, and the animal develops lameness on the affected leg. Crepitating, or the sensation of air under the skin, can be noticed as the area seems to crackle under pressure. Once clinical signs develop, the animal may only live a short while, sometimes as little as 12 hours. Occasionally, cattle will succumb to the disease without showing any symptoms at all, and only a post-mortem reveals the cause.

The diagnosis is by physical examination and confirmation of gram positive rods in the slide made out of serous fluid from the site. During post-mortem examination, a diagnosis is usually made very quickly, as the affected muscle is generally mottled with black patches. These patches represent dead tissue, killed by the toxins that the bacteria release when they infect a live tissue. If viewed under a microscope, small rod-like bacteria can be visualized to confirm the diagnosis.

Treatment is generally unsatisfactory due to the rapid progression of the disease; however penicillin is the drug of choice for treatment. Treatment is only effective in the early stages and as a control measure.

Prophylactic vaccination with a combined vaccine containing formaldehyde inactivated cultures of Pasturella multocida and Clostridium chauvoei adsorbed on aluminum hydroxide gel will give good immunity against BQ along with Haemorrhagic Septicaemia.

Primary vaccination: six months of age or above, followed by booster dose after one month.

Revaccination: Annually