Johne’s Disease: How are cattle affected?
Guy Sheppard, DVM
The Texas A&M Veterinary Medical Diagnostic Laboratory (TVMDL) has seen quite a few cattle testing positive for Johne’s Disease in the last several months. Clinically affected cattle are usually mature adults that are gradually losing body condition despite having a normal appetite. Chronic watery diarrhea is also usually recognized, but it can be sporadic during the syndrome.
The causative organism is Mycobacterium avium subspecies paratuberculosis. Most of the time, the animal is infected with the organism in the first six months of life followed by a long incubation period of months to years. All breeds of cattle, sheep, and goats are susceptible to Johne’s disease.
Testing for Johne’s disease is possible by analyzing a serum sample for antibodies to the organism, or by looking for the organism in feces using PCR or culture techniques. Since the incubation period for the disease is lengthy, testing young animals may result in false negative test results. No vaccine is available for the disease, so control methods involve removing positive animals from the herd and methods to reduce exposure to of young calves to the organism.
For more information about this case, contact Dr. Guy Sheppard, veterinary diagnostician at the College Station laboratory. To learn more about TVMDL’s test offerings, visit tvmdl.tamu.edu or call one of the agency’s full-service laboratories.
Reference
Grooms, D.L, Johne’s Disease, Blackwell’s Five-Minute Veterinary Consult: Ruminant; Scott R.R. Haskell, DVM, editor. 2008 pgs. 444-445.