Johne’s disease is a slowly progressive, diarrheal disease that causes major economic losses to the dairy and beef industries. Unresponsive to antibiotics, affected cows progressively lose weight, and despite a good appetite, alert behavior and lack of fever, they continue to go downhill. When clinical signs of diarrhea appear, the cow is usually shedding large numbers of bacteria in the feces throughout the farm, and it is in this period where owners unknowingly spread the disease to other farms by marketing an animal with Johne’s disease. Johne’s disease typically enters the herd via purchase of new cows that do not have signs of disease. Disease does not occur as outbreaks – there may be months between individual cases.

Figure 1. Emaciation and soiled rear quarters in a cow with Johne's disease.

• Herd management programs of sanitation and culling are keys to disease control
• Fecal culture tests are required to confirm a diagnosis
• Serologic (blood) tests are used for screening herds and are not diagnostic tests for individuals

CLICK HERE to see how Johne's disease affects the junction of large and small intestines. Bacteria are shed in feces and contaminate the cow (red).

Prepared by Drs. Norman F. Cheville, Charles O. Thoen, and John U. Thomson with support from the Iowa State Healthy Livestock fund and the Iowa State Legislature. The Johne's Disease Research Group at Iowa State University keeps Iowa's practicing veterinarians, producers and producer groups informed on the developents in the Johne's disease research and programs for control and eradication. Work is supported by funds from the Iowa Healthy Livestock Fund, the College of Veterinary Medicine, the Iowa Legislature, and Milk Producers Association. For further information, call Charles O. Thoen (515)-294-7608 or e-mail cthoen@iastate.edu.