RED DEER — Johne’s disease is a chronic and infectious disease of ruminants that can be a difficult condition to detect.
It affects the small intestine, and cattle become increasingly emaciated over time. The bacteria causing the disease hide inside immune cells, making it difficult to detect even with testing of milk, blood or feces. Symptoms start when cattle are two to six years old. They suffer persistent diarrhea and weight loss and do not respond to treatment. They become weak and die if they are not removed from the herd before that.
There are four voluntary programs in Canada in Alberta, Ontario, Quebec and Atlantic Canada focusing on education, risk assessment, management and testing in a widespread program that includes farmers, dairy breeds, the beef industry, veterinarians, universities and milk recording through CanWest DHI and Valacta in Quebec.
The intention is not to test to eradicate the disease but to control it with management, said Herman Barkema of the University of Calgary’s faculty of veterinary medicine, who is involved in the national and provincial Johne’s disease programs.
“You cannot control Johne’s disease in a couple of years,” he said at the Western Canadian Dairy Seminar held in Red Deer March 6-9.
“Our priorities were to increase the education and awareness of Johne’s disease among the producers and veterinarians.”
Almost 70 percent of herds participated, and 47 percent of the farms tested had positive samples.
“The true percentage of herds that were positive is not that different across the country,” Barkema said.
Alberta tested manure samples and Ontario used the milk ELISA tests.
The milk ELISA test has more false positive and false negatives. It cannot be assumed the cow is uninfected based on one negative test, but the probability that a cow is uninfected increases slightly with each subsequent negative test.
If a single ELISA test is positive, the cow is likely infected.
The program has taught the industry some valuable lessons and continuing research is needed.
Education is the key, and more workshops are needed to teach farmers and veterinarians about the disease, said Barkema.
“What we need with a disease like that is commitment for the long haul,” he said.
“We cannot control Johne’s disease in five years time. It takes five years before an animal gets sick. It takes 10 years to really make a dent in this disease.”
However, studies among producers and veterinarians have shown Johne’s is not high on their list of priorities. A recent national study showed lameness was the number one concern while Johne’s was seventh.
For those who did not participate in the program, farmers said they did not have time, doubted the effectiveness of tests or had no encouragement from veterinarians who were not convinced the program would work. Others said they did not think they had a problem.