Your veterinarian is best placed to advise you regarding a suitable testing method for Johne's disease.

Common diagnostic techniques1:

Culture: Culturing is the process of detecting MAP bacteria in faecal samples, by allowing the organism to grow on either solid or liquid media. This is generally considered the most accurate test available (it can detect infection between 80-98% of the time) however it is expensive and, because the bacteria grow slowly, takes a long time to run (up to 3 months to confirm a negative result). In a Pooled Faecal Culture (PFC) test, faeces are pooled from a large number of animals for the assay. This is more cost effective than working on individual animals. PFC is sensitive enough to detect MAP when only 1 animal in a pool of 50 is infected.

PCR (polymerase chain reaction)
The PCR test checks samples for the presence of gene segments from the MAP organism. The test demonstrates whether the organism is present but cannot tell if it was live when the sample was taken. There are limitations with the specificity of this test so a positive PCR result generally indicates further testing is warranted rather than being used as the sole indicator of herd status2 .

ELISA (Enzyme linked immunosorbent assay)
The ELISA tests blood (serum) or milk samples for antibodies produced in response to MAP bacteria in the animal. The test is rapid but expensive and less sensitive than culture. There is a potential for MAP-positive animals to test negative and vice versa.

Tissue Samples
Tissue samples are taken by biopsy or during post mortem examination (necropsy). The samples are homogenised and cultured for MAP and also evaluated microscopically by a pathologist.