Johne’s disease (pronounced YO-NEES), is a chronic illness caused by a mycobacterium. The contagious infection can technically be found in all ruminants. but it has drawn particular attention as an economically devastating disease in beef and dairy cattle.

Clinical signs of Johne’s – weight loss and diarrhea – are not unlike many other notable illnesses that stricken cattle. What is different about Johne’s disease is cattle don’t recover from it. The mycobacterium causes a thickening of the intestinal wall making it difficult for cattle to absorb any nutrients, so despite presenting with a normal, healthy appetite, animals essentially waste away.

The bacteria associated with this illness is shed through manure and milk, but it can also be transmitted in utero. The most common mode of transmission is fecal-oral, meaning cattle eat hay or drink water that has been contaminated. That being said, cattle are most susceptible to the disease when they are young calves, still drinking milk from their mom.

“What probably makes Johne’s most frustrating is animals are most susceptible to it when they are less than six months of age, but they often don’t show clinical signs until about three years of age or older,” said Dr. Anna Forseth, program veterinarian for the Montana Department of Livestock (MDOL).

To make matters worse, infected individuals could potentially shed the bacteria before they even show clinical signs. Testing for the disease can be done, but results can be inconclusive until cattle are at least two years of age. There is no antibiotic or vaccine for Johne’s, so unfortunately cattle either succumb to their illness or must be humanly put down.

Needless to say, Johne’s has the potential to be a rancher’s worst nightmare and its discovery within a herd is a proverbial Pandora’s box. Because the disease can be transmitted in utero, the offspring of infected cattle must also be tested.

Due to the disease’s implications and the fact it can incubate for so long within an individual, the state of Montana has initiated a voluntary Johne’s Control Program to help mitigate the spread of the disease. Following the lead of other states with similar Johne’s programs, the MDOL hopes that positive animals can be identified through the program, managed efficiently, and producers can purchase and sell livestock with greater levels of confidence.

“One of the goals of the program is to help producers figure out if they have Johne’s in their herd, and if they do have it, to what extent. From there, we want to help them take steps towards getting rid of it. On the other hand, if they test and don’t have it, the program offers support to help them keep Johne’s out,” Forseth said. 

Forseth emphasized the program is truly designed for all cattle producers in Montana, both commercial and seedstock. Producers can choose to either test individual animals that are infected or they suspect are infected, or producers can opt to have all their animals that are of an eligible age tested. The more animals that are tested will lead to higher certification in the program, which indicates a herd at lower risk for having and spreading Johne’s.

“We think a positive, managed herd is lower risk than a herd with an unknown status”,” Forseth pointed out.

Producers may feel uneasy about testing for Johne’s, especially since it is classified as a reportable disease in the state of Montana. However, Forseth wants all cattle ranchers to know that testing is completely confidential and the MDOL is required by law to keep it that way. There is no list and ranches aren’t given a black mark if they find a positive animal within their herd.

There are no quarantining requirements surrounding Johne’s in Montana, but there are federal restrictions on the movement of positive animals across state lines for purposes other than slaughter. Management for the disease is truly up to the individual producer and their herd veterinarian, although culling of infected animals is highly recommended. Reporting simply gives producers another level of expertise to help combat the problem.

Producers interested in Johne’s disease or the MDOL Control Program are encouraged to reach out to their herd veterinarians or the Montana Department of Livestock at 406-444-2043.