If you are raising any type of animal for dairy, it’s a good idea to know their tuberculosis status. TB is a zoonotic disease, which means animals can transmit it to humans.
Although most states are TB-free, the disease does still pop up sometimes in random slaughterhouse testing or in routine herd testing, mostly in cattle, and it is spreading. When I got my first goats in 2002, only Texas and Michigan had reported cases of TB, and that was the case for many years. In the past year, TB has been found in cattle in Texas, New Mexico, South Dakota, Michigan, and Indiana. (Note that when you click on that link, the first page is the brucellosis report. Page down for the TB map.)
There is a skin test for TB in cattle, which has been used in sheep and goats because they don’t have their own validated test. The rate of false positives (negative animals testing positive) in cattle is 2%, but no one knows what the corresponding rate is in sheep and goats because so few of them have been officially tested, according to Charles Gaiser, DVM, MPH, ACVPM of the USDA, who spoke at the American Dairy Goat Association Conference last month.
If you live in a state that is certified TB-free and all of your animals originated in certified TB-free states, odds are good that your animals don’t have the disease. Because the incidence of the disease is so low, most people who live in TB-free states don’t test.
Why test cattle, goats, and sheep for TB?
- If you sell livestock that will be shipped to other states, some receiving states may require TB testing, regardless of your state’s status. Some require only individual tests for the animals being shipped, although some may require a whole-herd negative test. For example, when I purchased goats from a herd in Michigan in 2002, the state of Illinois where I live, required a whole herd test within the past year, as well as current testing of the animals being imported into Illinois. Michigan had a known problem with TB, and Illinois was (and still is) TB free.
- TB testing may be required for showing in some states.
- If you live in a state where wild deer and elk have been found to have TB, such as Michigan, they could bring it onto your farm and infect your animals.
- The FDA’s Pasturized Milk Ordinance specifically requires TB testing of dairy herds that sell milk.
- You may want to have your animals tested if they were purchased at a sale barn or have an unknown health history, especially if you live in a state with known cases of TB.
The USDA has a website where they post monthly reports, so you can stay up-to-date on the TB status of your state.
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