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What is Johne's disease and can goats get it?

What causes Johne's disease?

What are the signs of Johne's disease and how
can I tell if my goats have Johne's disease?

How common is Johne's disease in goats?

How do goats get Johne's disease?

How can you prevent your animals
from getting Johne's disease?

How do you test animals for Johne's disease?

Can Johne's disease be cured?

Can humans get Johne's disease?

What is Johne's disease and can goats get it?

Johne's (pronounced "Yo-nees") disease is a contagious, slowly developing and fatal bacterial disease of the intestinal tract. A German veterinarian first described it in a dairy cow in 1895 and the disease was named after him. The disease is also called paratuberculosis.

Johne's disease primarily occurs in domestic and wild ruminant species such as sheep, goats, cattle, bison, deer, llama, etc. It has also infrequently been reported in non-ruminant species e.g. rabbits, primates, fox and stoat.

What causes Johne's disease?

The bacterium that causes Johne's disease is named Mycobacterium avium subspecies paratuberculosis. The name is abbreviated M. a. paratuberculosis or M. paratuberculosis. It is in the same family as the bacterium that causes tuberculosis in humans and animals and the type of disease it causes shares some characteristics with tuberculosis: it is slow to develop, it is resistant to antibiotics and is contagious. M. paratuberculosis can replicate only when within the animal; it cannot multiply in the environment. However, the bacterium reportedly can survive, still infectious, in the soil or water for over a year because of its resistance to heat, cold and drying.

What are the signs of Johne's disease and how
can I tell if my goats have Johne's disease?

This disease is hard to detect. The signs of Johne's disease are vague and months can pass after infection before they appear. Weight loss in animals with a good appetite may be the only indication as diarrhea is not a common sign in goats, unlike what is seen in cattle. The signs of Johne's disease can be confused with the clinical indications of other conditions such as parasitism, CLA (caseous lymphadenitis) or malnutrition. Of course, more than one problem may be occurring - for example, goats eventually succumbing to Johne's disease have improved clinically after treatment for parasites. Because of the slowly progressive nature of the infection, signs of Johne's disease are usually not seen until animals are adults.

How common is Johne's disease in goats?

Knowledge on the prevalence of this disease in the U.S. is limited, due both to lack of testing and reporting. It has been reported in a variety of goat species and in most countries raising goats.

How do goats get Johne's disease?

Johne's disease typically enters a herd when an apparently healthy, but infected, animal is introduced. This animal contaminates the premises (feed, ground, water) by shedding the organism in its manure. The organism is then ingested by other goats. Kids are thought to be most susceptible to infection - they can acquire the organism by suckling manure-contaminated teats and possibly from the milk/colostrum itself as a doe in the later phases of the infection may shed M. paratuberculosis directly into her milk/colostrum.

How can you prevent your animals from getting Johne's disease?

The best way to avoid this chronic infectious disease of course is to be as certain as possible that animals brought into the herd are not infected with M. paratuberculosis. Johne's disease test-negative herds are the best sources of animals for purchase. Since many herd managers do not yet test for the infection, assess the entire herd (not just the animals you intend to buy) for body condition. Ask the owner about the cull rate and common cause for culling - how many animals were thin/unthrifty for no confirmed reason? Check the body condition of the dam of kids you intend to purchase and have her tested if you have suspicions (tests on goats less than one year old are not likely to be informative unless exhibiting signs of the infection).

Following general rules of sanitation are helpful in blocking transmission of the infection. Feeders and waterers should be designed to minimize the likelihood of fecal contamination. Kidding should occur in clean, dry areas. Animals with weight loss or diarrhea should be segregated from the rest of the herd and tested.

How do you test animals for Johne's disease?

There are two common ways to test goats for Johne's disease: culture of fecal samples and blood tests for antibodies to M. paratuberculosis. The biology of the disease can make it difficult to detect infected animals, especially those in an early stage of infection. A truly infected goat in this "sub-clinical" phase may neither be shedding the organism consistently (thus the fecal culture may be negative) nor be making antibody in response to the infection (thus the blood test will be negative). Despite the potential "false-positive" results in some cases, collecting manure for culture and/or blood for testing by either the ELISA or AGID, as the two most useful blood tests are called, can provide valuable information needed to control the infection.

Can Johne's disease be cured?

Although few studies have been reported, Johne's disease is not considered a curable disease. As with most diseases caused by mycobacteria, the course of therapy is very long (months) and expensive. For most animals the best that can be expected is an improvement in clinical signs while under treatment, not a cure and treatment is cost prohibitive.

Can humans get Johne's disease?

This is a very controversial subject. There is a human disease called Crohn's disease that in some ways resembles Johne's disease. The cause of this chronic inflammatory bowel disease is not known and there is no known cure. A few laboratories have grown M. paratuberculosis from a few Crohn's patients' specimens but there is no evidence that the organism caused the disease. No connection has been shown between contact with animals with Johne's disease or milk consumption and Crohn's disease.