CAE, CL, and JOHNES DISEASE
Many goat raisers think of Caprine Arthritic Encephalitis (CAE), Caseous Lymphadenitis (CL), and Johnes Disease as equally dangerous and unmanageable diseases. While none of us wants to have them appear in our goats, the truth is that these are distinctly different diseases that require different responses.
CAE is a retro-virus (like AIDS/HIV). It is transmitted through colostrum, milk, and body fluids (including saliva, placental fluid, and semen). While devastating to the goat's health and milk production, CAE is not believed to be transmittable to humans. Concerned humans can pasteurize milk from CAE-positive goats.
Blood tests for CAE detect antibody production in response to infection by the CAE virus. Only very small amounts of antibody are produced in the early stages of infection and low antibody levels may not be detected by some blood tests. Testing should not be done before the goat reaches six to eight months of age and has a better developed immune response. Most female goats will develop detectable levels of antibody at or shortly after their first freshening (kidding).
CAE is incurable and untreatable. An immune system response is controlled by the genetics of the animal. The goat's immune system doesn't provide a good/curative response to the CAE virus because it doesn't recognize the virus as a threat to the health of the goat. Complicating the situation is that the CAE virus kills white blood cells that fight infection. No vaccine exists to prevent the disease and one isn't likely to be developed in the foreseeable future.
CAE is not manageable in any reasonable manner. Many dairy-goat producers do try to "manage" CAE by interjecting themselves into the birthing process, cleaning the kids rather than letting the dam clean them with her saliva, and bottle-feeding rather than allowing them to nurse her colostrum and milk. I object to this form of management because it perpetuates the disease. If dairy-goat producers would stop using semen out of CAE-positive bucks that sire high milk-producing does, I believe that CAE could be largely eliminated in their goats in a short period of time (perhaps ten years). However, this isn't likely to happen because they value high milk production above all else.
CL (Caseous Lymphadenitis) is caused by a bacteria that the goat's lymph system is able to filter to the outside of the animal's body into an encapsulated abscess, thereby eliminating its ability to make the goat ill. It is an amazing and wonderful process when you think about it. The bacteria can in theory be transmitted to humans but in fact seldom happens. This disease is transmitted only through oral ingestion of the pus or by direct contact with the pus through a cut on the body. CL does not pass through colostrum, milk, or bodily fluids.
The CL bacteria is filtered by the goat's lymph system to the underside of the skin, where it is contained in thick-walled abscesses that are impenetrable by antibiotics. The problem occurs when the abscess breaks open into the environment, spredding pus that can infect other goats. Internal abscesses are possible but more common in sheep than in goats. Slaughter facilities routinely identify and condemn abscesses in internal organs and allow the rest of the meat to be processed for food. The meat from CL-infected goats is safe to eat after the affected areas have been discarded.
Blood testing for CL has a high degree of accuracy, depending upon the type of blood test used, but the only way to be positive that the abscess contains CL bacteria is to test the exudate (pus). There are many types of abscesses. Two types often visually misdiagnosed as CL both by producers and vets are pasteurella abscesses and A. pyogenes abscesses. Bob Glass, owner of Pan American Vet Lab in Hutto, Texas (near Austin) has developed a test for culturing the contents of the abscess to determine if the bacteria is CL. Contact Bob at 1-800-856-9655 for more information. He also does blood testing for CAE, CL, and Johnes.
CL, while incurable when contracted, can be vaccinated against with the new vaccine (available since mid 2012) developed by Texas Vet Lab in San Angelo, Texas. My herd was one of several herds nationwide upon which the new vaccine was tested in 2011 prior to submission to the US Government for approval. I was privileged to announce this new vaccine in the May 2012 issue of MeatGoatMania (see archives) and I followed up in the July 2012 issue of MeatGoatMania with detailed information on how to use it and what to expect from it. Jeffers Livestock carries this vaccine (1-800-533-3377).
If you have not vaccinated against CL and your herd develops abscesses, have the pus tested by Pan American Vet Lab and lance the abscess and clean it out as described in my article on how to manage abscesses on the Articles page at www.tennesseemeatgoats.com. I no longer advise using 10% buffered formalin to manage abscesses because (a) people wrongly assume that all abscesses are CL abcesses, and (b) they use the 10% buffered formalin incorrectly, causing discomfort to the goat and sometimes making the situation worse.
While no producer chooses to have CL or any other infectious disease in the herd, CL is nowhere near the health, managerial, or economic problem that are CAE and Johnes Disease.
Johnes Disease is the goat equivalent of chronic wasting disease in deer. This bacteria passes primarily via fecal-to-oral contact, but it can also be shed and passed through milk. Chronic in dairy cattle herds and becoming more prevalent in goat herds, Johnes Disease stays in the ground for a very long time (no one knows how long). The Johnes bacteria is not killed by the "flash pasteurization" method (high temperatures for short duration) that is commonly used. It is very debilitating to infected goats and usually doesn't show up for years, resulting in the entire herd (and the ground they live on) being infected before symptoms appear. Johnes-infected goats should be culled and slaughtered for food consumption. The meat is safe to eat.
Johnes is not believed the be transmittable to humans, and it is incurable and untreatable in goats. If you suspect Johnes, contact Bob Glass at Pan American Vet Labs and test immediately.
Bob Glass of Pan American Vet Lab in Hutto, Texas performs blood tests to identify all three of these diseases. Bob has also developed a test pus to determine if the organism inside an abscess is the CL bacteria. Contact him at 1-800-856-9655.
If you suspect any disease in a goat, always use disposable gloves when handling the animal. Before you decide to cull the goat, you need to know what choices are available to you. Your goals and your managerial style will impact your decision. I present this information so that you can make that decision based upon facts rather than the incorrect information and emotional heresay of some vets and goat owners.
My thanks to Bob Glass of Pan American Vet Lab for his help with this article.
Suzanne W. Gasparotto, Onion Creek Ranch, Texas 5/9/15
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