Types of Tests
No single test is sufficient for all purposes, but reasonably accurate and cost-effective tests are available for different diagnostic and control needs. Johne’s disease tests are divided into two main types of tests: those that detect antibodies that an animal makes in response to infection (e.g. serum or milk ELISA) and those that detect the bacteria that causes Johne’s disease (e.g. culture or PCR (DNA probe)). Current tests do not identify animals at early stages of infection reliably; therefore, repeated testing is recommended.
Individual animals are tested with any of the options noted above. Producers may also elect to test environmental samples or pool individual samples using the tests that detect bacteria. Both of these testing strategies are effective in determining if the bacteria causing Johne’s is present in a herd. Submitting individually collected samples for the lab to pool may also be a cost effective way to use test results for making management decisions if the herd is not heavily infected.
Work with your veterinarian to determine what tests are most appropriate for your herd.
This will depend on each herd’s goals and resources. In general, annual testing is recommended, but some herds may wish to test more frequently (eradication) and some herds may elect not to test at all.
Testing for Herd Classification
Some producers may choose to classify their herd, especially if the herd is a low risk for Johne's disease or they are selling animals to other producers. For more information, see Herd Classification Program.
Submitting Laboratory Samples
Your veterinarian can submit samples to any laboratory approved for the Johne’s disease test elected.
It is very important that samples are correctly collected and submitted, with completed paperwork. For producers participating in the Herd Classification Program this is especially important to ensure the herd is appropriately classified.