Cats have been reported to develop CNS signs as a result of metronidazole intoxication. Fenner described this clinical condition in cats (WR Fenner. Diseases of the Brain, Spinal Cord, and Peripheral Nerves. In the Cat Diseases and Clinical Management, 2nd edition, 1994; 1507-1568). Typical signs include forebrain involvement with ataxia, weakness, disorientation, diminished postural reactions, seizures and apparent blindness. It should be remembered that severe vestibular signs may mimic generalized seizures. Treatment periods with metronidazole ranged from five days to 10 months prior to the onset of signs. Aside from the neurologic examination, the physical examination and laboratory tests were generally normal. Cats may exhibit changes in behavior after receiving diazepam.

Diazepam given to cats for several days may rarely be associated with hepatic failure. It is therefore questionable if diazepam should be employed in cats with metronidazole toxicity. Cats often begin to improve within 48 hours after discontinuation of the metronidazole and initiation of supportive therapy. Metronidazole remains a valuable aid in the therapy of many clinical conditions as long as the clinician remains aware of potential side effects and their management.

Editor's Note : Comments and questions can be directed to Pierre S. Bichsel, DVM or Ronald Lyman, DVM at the Animal Emergency and Referral Center, 3984 S. US Highway 1, Ft. Pierce, FL 34982; (772) 466-0460.