Johne's disease is a usually fatal and persistent infection that affects the small intestine of ruminants. Ruminants are cud-chewing hoofed animals such as cows, buffalo or bison. Johne’s disease is a type of Para tuberculosis of the cattle in which there is considerable loss of production. The disease affects young calves but the symptoms appear only after 2 years of age.
Johne’s disease is pronounced as YO-KNEES disease. As a side-effect of the disease, a soft swelling might occur in the affected cattle. This is why many people prefer to call it by the name Bottle Jaw.
The disease is caused by Mycobacterium paratuberculosis, a bacterium related to tuberculosis. The Johne’s disease germ is very persistent. It has the ability to live for a period of up to 12 months on the ground. As the bacterium prefers to live in the ground, most of the infection comes from the ground.
- Unexplained weight loss
- Strange diarrhea with normal appetite
- Soft swelling under the jaw
- Nursing cows have reduced milk production
- Production losses may be up to 10% for each affected animal
How it Affects Cattle
Johne's disease typically starts as an infection in calves. Visible signs do not appear until the calf is little older. The infection is difficult to detect in its early stages. The most common method of animal-to-animal spread is to the calf from its dam. The udder becomes a reservoir of germs and more calves can get infected if there is cross-suckling. Some calves may also be born infected. Once there is protein loss from the bloodstream into the digestive tract – the days of the affected animals is numbered. The cattle will not live very long, perhaps for only a few weeks.
Johne’s disease is spread everywhere. A national study of US dairies done in 1996 found that in almost 1 out of 4 dairy farms, 10% of the cattle are infected with Johne's disease. The areas which are affected most by the disease are those farms which practice intensive agriculture.
Risks & Dangers
The risk of getting infected by Johne’s disease is there before as well as after birth. Infection happens from the mother. Milk from infected cows is also considered a high risk. Artificial insemination and embryo transfer are also considered as risk sources of contamination. The infection from an infected animal without any clinical signs to a healthy one can rarely be prevented.
A permanent cure for Johne’s disease hasn’t been developed as yet. But the spread of the disease can be effectively managed and for this a veterinarian should definitely be consulted.
Vaccines & Prevention
Calves should be born in a healthy environment. There should be a positive effort to reduce the newborns exposure to manure from adult animals. Collecting milk from different animals and then feeding them to young calves should be avoided. All the affected as well as healthy females of the herd should be identified. Since the mothers spread the disease at an early stage, precautions should be high for them. All the affected animals should be separated from the herd and preferably culled.
References and Resources
- Johne's Disease in Cattle Herds - New South Wales Government
- Johne's Disease - USDA
- Johne's Disease - Iowa State University
- Preventing the Spread of Johne's Disease in Cattle - New South Wales Government
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