Johne’s Disease in Goats
3
Q:
Why do goats with clinical signs of Johne’s disease
to eat well, infected goat soon become emaciated and weak. Johne’s (“YO-knees”) disease is alose fatal gastrointestinal weight and become weak? Since the signs of Johne’s disease are similar to those for disease of goats and other ruminants (including cattle, other parasitism, sheep, elk, deer, and bison) that is caused bacterium When by an the animal is infected several with MAP, thediseases— bacteria reside in dental disease, Caseous the last part of the small intestine—the ileum—and the intestinal lymph Lymphadenitis (CLA) and Caprine Arthritis-Encephalitis Virus Mycobacterium avium subspecies paratuberculosis (MAP). nodes. At some point, the infection progresses as bacteria multiply and (CAEV)—laboratory tests are needed to confirm a diagnosis. Also known as paratuberculosis, this infection is contagious, take over more and more of the tissue. The goat’s immune system When an animal with signs of Johne’s disease is discovwhich means it can spread in your herd. responds to the bacteria with inflammation that thickens the intestinal ered, it is very thataother The MAP organism is most commonly passed in theabsorbing mawall and prevents it from nutrients. As likely a result, goat infected in the animals—even those that still appear healthy— are in the herd. Control of the nure of infected animals. The infection spreads from clinically ill usually stage of Johne’s disease in effect starves to death. At this infection that you and tract, your veterinarian address it in adult goats to kids and occurs when young animal stage thea organism mayswallows also spread beyondrequires the gastrointestinal travelling in the blood to muscles or other major organs such as the liver the whole herd and not just on an individual the organism via water, milk or feed that has been contamor lungs. animal basis. inated by manure from infected animals. Most owners are When an animal is taken by surprise when the ininfected with MAP, the fection is diagnosed, and learn bacteria reside in the too late that the infection has last part of the small taken hold in multiple animals intestine—the ileum— in a herd. and the intestinal lymph Due to lack of testing and nodes. At some point, reporting, it is not known how the infection progresswidespread Johne’s disease es as bacteria multiply is in goats in the United and take over more and States. The infection has more of the tissue. The been confirmed, however, in goat’s immune system many goat herds throughout responds to the bacteria the country—in milk, meat, with inflammation that heritage and other breeds— thickens the intestinal and it is a problem in most Top: Thickened intestinal mucosa caused by Johne’s disease. wall and prevents it other goat-rearing countries Bottom: Thin, pliable, normal intestine from absorbing nutrias well. The costs of this ents. As a result, a goat infection range from economin the clinically ill stage of Johne’s disease in effect starves to ic losses—due to reduced production and increased culling death. At this stage the organism may also spread beyond for meat and milk animals—to emotional losses—for those the gastrointestinal tract, travelling in the blood to muscles whose goats are more pets than agricultural investments. or other major organs such as the liver or lungs. There is no cure for Johne’s disease, and there is not Since there is no cure for Johne’s disease, control of the anapproved vaccine for goats in the United States to help protect them rom infection. Therefore, prevention is the key infection is critical. Control of Johne’s disease takes time and a strong commitment to management practices focused on to control. keeping young animals away from contaminated manure, A goat that appears perfectly healthy can be infected milk, feed and water. A typical herd clean-up program may with MAP. Although goats become infected in the first take a number of years. The basics of control are simple: new few months of life, many remain free of clinical illness until infections must be prevented, and animals with the infection months or years later. When goats finally do become ill, the must be identified and removed from the herd. symptoms are vague and similar to other ailments: rapid photo by Karla can Blackstock Your State Designated Johne’s Coordinator help you weight loss and, in some cases, diarrhea. Despite continuing
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40 - The Boer Goat
