Oropharyngeal lesions and poisoning by closantel in sheep after antiparasitic treatment

ABSTRACT

An outbreak of oropharyngeal lesions and poisoning by closantel in sheep after improper handling and anthelmintic drug overdose is described here. Eleven sheep were affected out of 42 that were dewormed. Eight sheep died. Clinically, the animals showed abdominal recumbency, absent pupillary and palpebral reflexes, bilateral blindness, depression, apathy, emaciation, and corneal opacity. Three sheep exhibited swelling on the right side of the mandible. At necropsy, one sheep exhibited a purulent lesion located on the right, next to the root of the tongue. Microscopically, the main finding was status spongiosus in the central nervous system and optic nerve. The retina showed rod and cone degeneration, ganglionic cell layer vacuolation, karyorrhexis, and vacuolation of the outer plexiform layer. The liver of one sheep exhibited diffused coagulative necrosis of hepatocytes in the centrilobular region associated with high infestation of Haemonchus contortus.