A Negative Johne’s Test For An Individual Animal

Some breeders portray their animal Johne’s status by saying “it has tested clear”. This may be true on the day but it is meaningless as even the best tests  can only identify animals as they begin to breakdown and start showing symptoms.  Hence in an infected herd the vast majority of animals will test clear but may test positive several years later.  This is why the official herd health status boards produced for bull sales etc do not have an individual animal box – just but a single herd box stating the status for the whole herd.  Such boards are only produced by the independent CHeCS registered groups which impose the most stringent rules possible to give an accurate description of the herds and hence the animals within it, Johne’s status.  Breed societies also do not support individual animal status.

Unfortunately statements on the Johne’s status of an animal, based on a single test are meaningless.

Basil Lowman, basil.lowman@sac.co.uk