Abstract
A commercial dairy goat herd of 600 animals experienced sudden onset of arthritis/polyarthritis, clinical mastitis, and sudden death in does. The offending infectious agents were Mycoplasma agalactiae and M. mycoides subsp. mycoides (caprine biotype). The disease syndrome began approximately 4 weeks following the 1) introduction into the herd of a lactating doe with no apparent clinical signs and 2) a breakdown of proper hygienic conditions in the milking parlor. Over a period of 3 weeks, 90 does (15%) either died or were culled because of arthritis/polyarthritis and mastitis. A management decision resulted in only the does affected with M. mycoides subsp. mycoides being submitted for necropsy; those affected with M. agalactiae, which were in a different “string,” were not submitted for evaluation. Gross necropsy of the does affected with M. mycoides subsp. mycoides showed purulent discharges from the udders, enlarged supramammary lymph nodes, enlarged and firm spleens, and swollen livers. Microscopic findings were characterized by a loss of vascular integrity and diffuse fluid leakage in multiple organs. Antibiotic therapy with tylosin was attempted but was not successful. The outbreak was terminated following the removal or segregation of affected does and implementation of hygienic conditions in the milking parlor.