Mycobacterium chelonei Mastitis in a Quebec Dairy Herd.

An epizootic of bovine mastitis caused by a nontuberculous mycobacterial agent occurred in a large Quebec dairy herd. This mastitis problem was characterized by the occurrence of a high number of cows with severely inflamed, indurated and therapeutically incurable quarters. Routine diagnostic laboratory methods yielded negative cultural findings. Approximately 40% of the milking cows developed chronic mastitis. Poor sanitation, improper milking procedures and a faulty milking system prevailed at that time.