Black Quarter (BQ)

What is black quarter (BQ)?

Black quarter, also called blackleg or BQ, is a serious disease of the muscles. It is caused by Clostridium chauvoei, a germ whose tough spores can survive in soil for many years. Animals pick up the spores while grazing. The spores rest quietly in the muscles until a muscle is bruised or strained. Then they wake up, multiply and make toxins (poisons) that destroy the muscle and fill it with gas.

BQ mostly strikes young, well-grown cattle, usually between about six months and two years of age. Buffaloes can also be affected. It does not spread directly between animals, but a carcass can leave spores in the soil.

Signs to watch for

Common signs include:

• Sudden lameness, often in a hind leg or a shoulder
• A hot, painful swelling over a thick muscle such as the thigh, hip, shoulder or neck
• A swelling that later feels cold and crackles under the skin when pressed
• High fever, dullness and loss of appetite
• Stopping chewing the cud

Not every animal shows every sign. Often the first sign is a young animal found dead.

Which lab tests help

Black Quarter (Clostridium chauvoei) RT-PCR looks for the DNA of the germ in a piece of affected muscle or a swab, which your vet collects. A stained smear of fluid or tissue from the swelling, for example a sample checked with FNAC (Fine Needle Aspiration Cytology), can show rod-shaped bacteria. Other clostridia look the same under the microscope, so PCR is used to tell them apart.

Histopathology / Biopsy of affected muscle shows the damage under a microscope. In a living animal, CPK (Creatine Phospho Kinase) can show muscle injury, but it cannot name the cause. Sudden deaths have other causes too, such as haemorrhagic septicaemia (HS), so your vet may add Haemorrhagic Septicaemia (Pasteurella multocida) RT-PCR.

A registered veterinarian interprets every result together with the animal's signs and history. The lab confirms the method, sample needs and reporting time when you book.

When to see your vet

Call a vet at once if a young animal is lame with a swollen, painful muscle or a high fever, because BQ can kill within hours. Sudden death can also be caused by anthrax, which can pass to people, so do not cut open a dead animal yourself. Wear gloves if you must touch it, wash your hands well and see a doctor if you feel unwell. Your vet will advise how the carcass should be disposed of. If several animals fall ill or die, tell your veterinarian or the animal husbandry department. Ask your vet about vaccination or prevention for your young stock.

Testing in Bhopal

Pashupatinath Vet Lab is at C-200, C Sector, Shahpura, Bhopal. Sample collection is free anywhere in Bhopal. Farmers in other districts can send samples by courier, by bus parcel or through their local vet, and the lab coordinates by phone or WhatsApp on +91 88175 01118. Reports come on WhatsApp, by e-mail and in My Reports on the website.