East Wisconsin Dairy Herd Improvement
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Dairy Herd Improvement Cooperative
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Introduction to Johne’s Disease

Johne’s disease was first identified in the U.S. dairy industry over 100 years ago, yet many producers are still unfamiliar with this serious, infectious disease. Johne’s disease, is a chronic, infectious disease which affects domestic and exotic ruminants including dairy and beef cattle, sheep, goats, cervids and camelids. It has been called one of the most serious diseases affecting cattle today.

The disease is caused by Mycobacterium paratuberculosis, a slow-growing bacteria. This bacterium invades the animal’s small intestine causing a thickening of the intestinal wall, reducing the absorptive capability of the intestine. According to researchers at Michigan State University, the bacteria are taken up by specialized cells in the small intestine. As the body tries to rid itself of these bacteria, the immune response causes a thickening of the intestinal lining, preventing it from functioning normally. This leads to poor absorption of nutrients and eventual diarrhea. As a result, although animals may be feeling and eating well, they begin to lose weight.

Because of the slow, progressive nature of the infection, signs of Johne’s disease may not be seen until years after the onset of infection. The clinical signs of Johne’s can be easily confused with several other diseases, including intestinal Parasitism, malnutrition, salmonellosis, hardware disease and winter dysentery. The most definitive way to determine the presence of Johne’s is through testing.

Clinical SignsStages of DiseaseOnset of InfectionPrevalenceContinuing InformationReferences

Clinical signs in cattle, include profuse watery diarrhea, weight loss, and lowered milk production. Appetite will stay the same or increase. Some animals may have a low-grade fever, and develop edema under the jaw (bottle jaw).

Johne’s disease in a herd is said to be a silent disease. It may loom in the herd for years before a clinical case surfaces. The presence of infection in the herd is hard to detect until the disease has progressed to the second or third stage.


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