Johne's disease
Also called Paratuberculosis
A slow bowel infection of cattle, buffalo, sheep and goats that causes steady weight loss and, in cattle, persistent watery diarrhoea. It is picked up when young but shows up years later.
Cause and spread
- Cause
- Mycobacterium avium subspecies paratuberculosis (MAP).
- How it spreads
- By the faecal-oral route: young animals swallow dung, colostrum or milk contaminated by adults that shed the bacteria. Signs usually start 2 to 5 years later in cattle.
Signs to watch for
- Weight loss and wasting despite a good appetite
- In cattle, long-lasting watery diarrhoea without blood
- Lower milk yield and a rough coat
- Swelling under the jaw or along the belly (bottle jaw) from low blood protein
- In sheep and goats, mainly weight loss, often without diarrhoea
Many diseases look alike. Only a laboratory test can tell them apart, so please see a veterinarian for any sick animal.
How it is diagnosed
Early infection is hard to find: tests on individual animals are unreliable in young animals and in animals that are not yet shedding. Antibodies in blood (ELISA) and the bacteria's genes in dung (PCR) are used, often on several animals and more than once.
Prevention and control
- Buy replacements only from herds with good records and negative tests
- Keep calves away from adult dung and raise them on clean colostrum and milk
- Remove animals with signs and do not breed from them
- Vaccines are available in some countries and can reduce signs and shedding
Where this information comes from
- Paratuberculosis, Johne's disease (factsheet) · Center for Food Security and Public Health, Iowa State University
General information for animal owners and veterinarians, last checked October 2026. It does not replace the advice of your veterinarian, who should decide which tests and treatment your animal needs.