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Black quarter (BQ, also called blackleg) is a soil-borne bacterial disease of cattle and buffalo caused by Clostridium chauvoei. It mainly strikes well-grown young animals between 6 months and 2 years, causing sudden high fever, lameness and a hot, painful swelling — usually on the thigh or shoulder — that crackles under the fingers. Death often follows within 12 to 48 hours, so BQ is always a veterinary emergency. Early antibiotic treatment occasionally saves an animal, but annual vaccination before the monsoon is the only reliable protection.
The bacteria survive for years as spores in soil. Grazing animals swallow spores with grass or soil; the spores pass into the bloodstream and sit silently in muscle. When a muscle is bruised or stressed, the low-oxygen conditions wake the spores, the bacteria multiply and release toxins that destroy muscle and poison the whole body. This is why the disease so often appears without warning in the best-grown, most active young animals — not the weakest ones.
Rain and flooding bring buried spores to the surface, and lush monsoon grazing means animals eat closer to the soil. Waterlogged, freshly excavated or flood-affected pastures are classic BQ ground, and most Indian outbreaks cluster in the monsoon and post-monsoon months — the same season as haemorrhagic septicaemia (HS). Our monsoon herd health guide covers the wider rainy-season picture.
HS typically causes throat/brisket swelling and severe breathing difficulty; frothy bloat shows a drum-tight left flank soon after lush grazing; BQ shows lameness plus a crackling muscle swelling on a limb. All three are same-day emergencies — do not wait to be sure. Describe the signs to your veterinarian on the phone while help is on the way.
Vaccinate all cattle and buffalo from about 6 months of age, every year, ideally in May–June before the rains. In many states BQ vaccine is given combined with HS vaccine in one shot during pre-monsoon drives — our full cattle vaccination schedule for India shows how BQ fits alongside FMD, HS and brucellosis. In known BQ villages, veterinarians often advise vaccinating young stock slightly earlier and repeating annually until animals cross two years — the highest-risk window. Avoid grazing young stock on freshly flooded or newly dug ground in high-risk weeks.
The rare animal that survives BQ has been through high fever, tissue damage and a heavy antibiotic course, and usually comes back to feed slowly. Offer soft green fodder, clean water and shade. To rebuild rumen function and appetite, many farmers use Cattle Remedies Ruminova — an improved formulation for consistent rumen and digestive support — alongside Cattle Remedies Grazup for appetite, and a liver tonic such as Heprich to support metabolism during convalescence (see our liver tonic buying guide). These support recovery — they are not treatments for BQ itself, which only urgent veterinary care can attempt.
Not directly. Animals pick up spores from soil and pasture, not from each other. But a case on your land means the soil is contaminated, so the rest of the young herd is at real risk and needs vaccination cover urgently.
Fast-growing, well-muscled animals between 6 months and 2 years are the classic victims — their active muscles provide the low-oxygen conditions the bacteria need after minor bruising. Older animals have usually built immunity through low-level exposure.
No. BQ progresses in hours, and only very early veterinary antibiotic treatment has any chance. Spending time on home remedies almost always costs the animal's life. Vaccinate every year instead — it is cheap and highly effective.
This article is for education only. Black quarter is a fatal emergency — contact your veterinarian immediately if you suspect it, and follow your district's vaccination schedule.
