Ionophore antibiotic (narasin) poisoning in rabbits.

Outbreaks of narasin poisoning in rabbits from several commercial rabbit-raising farms in the state of Parana, Brazil, are reported. Approximately 5,000/35,000 rabbits died after having consumed a pelleted ration to which poultry ration premix had been added. Clinical signs included apathy, anorexia, muscle weakness, impaired walking, diarrhea, respiratory distress, and opistothonus. Gross findings were not remarkable, but varying degrees of degeneration, necrosis and regeneration of skeletal muscles were consistent histopathological features in affected rabbits. Myocardial changes were mild or absent. Thirty ppm of narasin were detected in the ration fed the rabbits. The disease was experimentally reproduced by feeding the suspected ration and by administering narasin po to rabbits.