Johne’s Disease: Control and Elimination (part 3)

– William Shulaw, Extension Veterinarian, Cattle and Sheep, Ohio State University

Controlling or eliminating Johne’s disease in a herd takes time and commitment. A final observation from the Demonstration Herd Project is that the herd owner must become well informed about the disease and set realistic goals. If this includes making rapid progress, and perhaps eventual elimination, careful consideration regarding retaining home-raised heifer replacements must be given. One of our beef herds had made the decision to try to eradicate Johne’s disease from their herd before they were enrolled in the Project in 2004. To their great credit, the owners had recognized the possibility that a replacement heifer could become infected as a calf and not begin shedding for several years. This could destroy a lot of hard work and expense after considerable progress toward that goal had been made by exposing a future calf crop to MAP. Before 2004, they made the decision not to keep their own heifers until they had reason to believe the disease was gone or nearly so. Toward that end, they have purchased some heifers from a herd enrolled in Ohio’s Test-Negative Status Program. After removal of two cows following the first sampling in the fall of 2004, and one more after sampling in the spring of 2005, they have had six consecutive, semi-annual, whole-herd tests with all negative culture and blood test results. Continue reading

Johnes Disease: Testing Alternatives (Part 2)

– William Shulaw, Extension Veterinarian, Cattle and Sheep, Ohio State University

Over the last thirty years, a number of test methods have been developed in an effort to provide producers with a better diagnostic test. The current culture method available at Ohio’s Animal Disease Diagnostic Laboratory (ADDL) in Reynoldsburg uses liquid culture media and is perhaps the most sensitive method yet developed. Herd culture results are available in six to seven weeks, and individual positive cultures can be detected in as little as two weeks. This is a significant improvement over the previously used technology that took up to 12-16 weeks to complete. Culture of manure and tissue is still the “gold standard” for diagnosis of infection with MAP. Blood tests for Johne’s disease can be completed in less than a week and are much less expensive than culture. The current method used in most laboratories is referred to as an ELISA, and this test has been markedly improved in the past decade. However current research, including our observations in our demonstration herds, suggests that it is much less sensitive than culture. The ELISA only identifies 70-80% of cows that are heavy shedders, and perhaps only 10-30% of light and moderate shedders compared to manure culture. This test may help a producer determine whether they have Johne’s disease in their herd, but testing and culling based on ELISA results may leave animals remaining in the herd to contaminate the environment. Continue reading

Johne’s Disease: What have we learned from our Demonstration Herd Project? (Part 1)

William Shulaw DVM, Beef and Sheep Extension Veterinarian, Ohio State University

In late 2003, the USDA provided funding for interested states to participate in the National Johne’s Disease Demonstration Herd Project. The primary objective of the project is to evaluate the long-term effectiveness and feasibility of various management-related disease-control measures for Johne’s disease on dairy and beef cattle operations. Secondarily, the program has provided for educational opportunities for producers and veterinarians highlighting diagnostic testing and management and control strategies. Currently, 17 states with 66 dairy herds and 22 beef herds participate in the program. Ohio enrolled three herds in the summer of 2004, one dairy herd and two beef herds. Continue reading