Johne's vaccine injection site
The vaccine used in the U.S. is a mixture of killed mycobacteria and oil. It can sometimes cause large lumps at the site of injection, usually the brisket region. Occasionally these lumps will become draining abscess-like lesions. Although the vaccine is given to calves less than 30 days old, the tissue reaction at the injection site may last for the life of the animal. The efficacy of the vaccine is controversial.