Losses related to the ingestion of lincomycin-medicated feed in a range sheep flock

Because of an episode of abortion caused by a tetracycline-resistant Campylobacter jejuni, lincomycin was mixed into a barley pellet and fed to 3,000 range ewes at a dosage of 225 mg/ewe/day. After the second feeding, a number of ewes were anorectic and diarrheic, and 6 were dead. Necropsies revealed congestion and hemorrhage of the entire gastrointestinal tract. The feeding of the medicated pellets was discontinued immediately. Sick ewes were treated with antihistamines and corticosteroids, but they did not recover, and many died during the next several weeks. Lambs born within the first 7 days after the incident were alert and vigorous. Dams did not produce milk and many died during or after parturition. Later, however, lambs were born dead or weak, and abortions of autolyzed lambs began. Affected ewes examined 3 weeks later had salmonellosis and/or toxic tubular nephrosis associated with an oxalate-like crystal. The flock had been grazed on range infested with Halogeton glomeratus just before treatment with lincomycin, and it also had a history of Salmonella-related abortions. The deaths finally ceased after a month. Approximately 2,000 ewes and 3,200 lambs were lost, resulting in an economic loss of $550,000.