Johne's Disease in Cows
I own a few beef cows. This spring, one of my older females began to lose weight. Her milk production dropped drastically (she had a calf on her side), and she had watery diarrhea. My veterinarian drew blood and collected a fecal sample to test for Johne’s . She was positive on both so I sold her. What exactly is this disease, and is it possible for my other cows to contract it? Also, am I at any risk?
Johne’s disease is a serious concern for all ruminant animals. There is no vaccine or cure, and once signs develop, death is inevitable. It is caused by the bacterium Mycobacterium paratuberculosis which is shed in the feces of infected animals.
Susceptible animals contract it through contact with fecal-contaminated feed, water and the environment, or through birth from an infected dam. Transmission is primarily through the fecal-oral route. The female you described is a true clinical case. The animal will lose weight, have watery diarrhea, and poor feed efficiency (even though feed consumption doesn’t normally drop) and poor milk production.
Because the disease takes some time to progress, animals younger than thirty-six months of age will typically not show clinical signs although they could still harbor the disease. It is possible for your other cows to also have the disease.
The State has a voluntary program for the prevention and control of Johne’s disease through which your veterinarian can come to your farm, evaluate your risk for Johne’s disease and do some testing. Herds that test negative can also become certified as a low risk test negative herd.
The public health risk of Johne’s disease and any relationship to a similar disease in humans known as Crohn’s disease remains uncertain and unproven. There is no known risk to you as the producer or consumer. While the disease is very clinically similar to Crohn’s disease in humans, the exact cause has not yet been determined.
We would recommend calling your veterinarian to discuss enrolling your herd in the voluntary program. For more information you can also contact the office of the State Veterinarian.