Experimental Brucella abortus infection in the horse: observations during the three months following inoculation.

Five mares, one stallion and a colt foal were inoculated intraconjunctivally with Brucella abortus strain 544. No clinical signs of disease developed except mild pyrexia. Intermittent bacteraemia was detected in the mares but not in the stallion or foal. Antibodies to B abortus became detectable from the second week after inoculation. Titres in the serum agglutination and complement fixation tests declined substantially after six to eight weeks but reactions to the Coombs antiglobulin, 2-mercaptoethanol and immunodiffusion tests were maintained. No consistent changes in biochemical or haematological values were observed. Post mortem examination of the foal disclosed granulomatous lesions in the lungs, liver, testes and metatarsophalangeal synovial membranes. B abortus identical with strain 544 was recovered from lymphoid and other tissues.