The possibility of bringing Johne’s onto your farm is one reason you should not buy goats from the sale barn. Although Johne’s is rare in goats, it also infects cattle and sheep, which means that a goat that was healthy when it arrived at the sale barn could pick up the disease while there. Although Johne’s is just one of many diseases that an animal could pick up at a sale barn, it can be one of the most devastating.
It is a disease that comes onto your property through the introduction of a new animal that appears to be perfectly healthy. An animal can be carrying Johne’s and shedding the bacteria in feces, contaminating the pasture, before they appear to be sick. Transmission is fecal-oral, meaning that your entire herd could be infected in short order. Johne’s can survive on the pasture for several years.
The only way to know if an animal has Johne’s before it shows symptoms is to test. There is no test for Johne’s that is extremely accurate in detecting infected animals, which means that it is not terribly informative to have a single negative test result on a single animal. It is more reassuring to have a whole herd test negative, and it is even more reassuring to have annual negative whole herd tests. After several years of negative results in a closed herd, the odds of Johne’s in that herd are as close to zero as one can get. Because Johne’s is so contagious, more than one animal in a herd will have it, so odds are much better that there will be some animals testing positive in the whole herd test if the disease exists in that herd.
The most common age for infection to occur is in the first month or two of a goat’s life, although they won’t develop symptoms for a couple of years. Older goats that are exposed to Johne’s may not contract it.
Weight loss is usually the only symptom of Johne’s in goats, but weight loss is also associated with parasites, dental issues, and other diseases and causes. Even social hierarchy within the herd can mean one goat isn’t getting its fair share of hay during winter when pastures are dead. Bucks also tend to lose a lot of weight during breeding season, sometimes as much as 20–30 percent of their normal body weight. Because copper-deficient goats tend to have poor parasite resistance, their body condition may be poor even when they have a small parasite load, which leads some owners to worry that their goat has Johne’s.
There is no vaccine and no cure for Johne’s, so if you have an animal with the disease, euthanasia may be the best solution.
This is an excerpt from Raising Goats Naturally: The Complete Guide to Milk, Meat, and More, 2nd Revised Edition by Deborah Niemann.