How is the spread of Johnes disease controlled between farms?
The best way to avoid the spread of Johne’s disease to your farm is to be as certain as possible that animals brought into your herd are not infected with M. paratuberculosis. Laboratory tests for cattle are more widely available than for elk or deer but suitable tests can be performed by some laboratories. Ask your veterinarian to find one for you. Screening tests performed on the whole herd from which you purchased the animal are more meaningful than tests done on only the animal you bought. Johne’s tests are not 100% sensitive, meaning that tests done on individual animals might not detect every infected animals. It is better to rely on tests done on the herd of animals from which you want to buy. If a whole herd test is negative, then the probability the herd is free of M. paratuberculosis infection is very high. This means that any member of that herd is very likely to be free from M paratuberculosis infection. Johne’s disease test-negative herds are the best sources of animals fo
