Chipping away at the challenge
For herds struggling with Johne’s disease, Hansen advocates use of the NJWG’s Risk Assessment model. This comprehensive checklist encourages the producer and veterinarian to canvass the operation, identify holes in management and get started on positive changes to bring the disease in check. He recommends tackling the management areas that pose the biggest risk for Johne’s transmission first. Often, this is newborn calf management. Then, proceed to the next age group until all of the animals in the herd are addressed. Finally, develop a plan for screening outside animals entering the herd.
“I prefer the approach of ‘test and manage,’ versus ‘test and cull,’” says Hansen. “Ideally, you want every positive animal out of the herd. But that’s not economically practical for most dairy operations. A highly infected animal will eventually cull herself. In the meantime, diligence must be exerted to limit her risk as a potential shedder of M. paratuberculosis to young calves. You need to help producers manage that risk.”
Even in herds that have eliminated or never had a Johne’s problem, Hansen recommends ongoing surveillance. “Johne’s is no longer an isolated problem,” he says. “It’s an industry problem, and every dairy herd in the country needs to worry about it.”
In these lower-risk herds, Hansen recommends fecal culturing of environmental samples at least once a year. Some of the best locations to collect such samples are a high-traffic area like the path out of the parlor or the lagoon entrance. If a positive sample is found, the herd should be assumed to be Johne’s-positive, and ELISA testing of all individual animals, at the same stage of pregnancy, should be resumed or started to get a handle on Johne’s prevalence in the herd.
Because Johne’s is a dynamic disease, Hansen stresses continuing education for veterinarians. “Most states have Johne’s veterinary certification programs either through their state VMA or department of agriculture,” he explains. “The online Johne’s certification training offered by the
Looking ahead, Hansen sees Johne’s disease as an ongoing -- but not impossible -- challenge for the
Joe Itle, VMD, has found that the herd managers who have become accredited and certified in brucellosis and tuberculosis (TB) eradication programs are the ones who are most receptive to Johne’s control.