Wyoming producers should take note of Johne’s disease exposure risk
Caused by an organism similar to that of bovine Tuberculosis, Johne’s disease can affect sheep, goats, cattle and other ungulate species.
“It is in the same family of bacteria as bovine Tuberculosis,” notes Wyoming State Veterinarian Jim Logan.
Nationally, Johne’s disease is most prominently found in dairy cattle but in Wyoming, where dairy cattle are scarce, it is more often seen in beef.
“It is reported once or twice a year on average in Wyoming,” Logan says.
Although Logan is not aware of any states that require testing, Johne’s disease is a reportable disease in Wyoming.
“We do not quarantine,” he states.
It would be nearly impossible for the herd to be proven clear of the disease and be removed from quarantine.
“We work with producers and their veterinarians on a case-by-case basis, helping them to learn about Johne’s disease and how to deal with it in their herd,” he comments.
The most common clinical sign for the disease is severe, chronic diarrhea that does not respond to treatment.
“The animal then loses weight and condition,” Logan continues.
He adds that there are currently no effective vaccinations or treatments for Johne’s disease. The best way to manage for it is through good biosecurity and culling.
“If an animal shows symptoms of Johne’s disease, it should be isolated to reduce or minimize risk and exposure to other animals, and a veterinarian should submit samples to a veterinary laboratory,” Logan states.
Also, caution should be taken when new animals, such as bulls or replacement heifers, are introduced to the operation.
“Many cases in Wyoming have come from imported animals or from breeding with animals from other states,” notes Logan.
Keeping new animals separate for a few weeks, up to a month if possible, allows producers to observe any signs of disease that may appear before introducing new animals to the rest of the herd.
“The bacteria can be harbored in some animals that are subclinical or asymptomatic carriers,” he comments.
The bacteria is then shed in feces and can be picked up by other animals through ingestion.
“Calves are the most likely to pick it up,” Logan says.
Some resistance to the bacteria has been noted in older animals.
“Once an animal is infected, it is infected for life,” he explains.
Incubation periods for the bacteria are often prolonged and variable.
“It can be months to years before symptoms show up,” states Logan.
Currently, there are no consistent high-quality tests available for Johne’s disease.
“We have some tests, but they are not great tests,” Logan notes.
Serologic tests that analyze blood serum in a lab or feces tests are performed only when there is cause for concern.
“It is not practical to test herds on a large scale basis,” he explains.
Because the bacteria are occasionally detected in Wyoming, Logan believes that producers should be aware of the possibility of Johne’s disease.
“In my experience, we have had reports of it year-round,” he says. “However, anything that creates stress can precipitate episodes of the disease.”
This means that extreme weather should be a factor that producers take into account. Logan reiterates that good management and good biosecurity are important mitigation factors.
“Johne’s disease is certainly something that producers should be aware of,” he says.
Natasha Wheeler is editor of the Wyoming Livestock Roundup. She can be contacted at firstname.lastname@example.org.