Pyridostigmine bromide intoxication in two domestic cats

A one-year-old female neutered cat died soon after presentation with severe signs of a cholinergic crisis. Its sibling was presented soon thereafter, in which cholinergic signs were also readily apparent. The owner, a myasthenia gravis patient, used pyridostigmine bromide tablets, and it was hypothesised that a pyridostigmine bromide intoxication was the cause of this cholinergic crisis. Treatment with 0.1 mg/kg atropine injected intramuscularly soon alleviated most of the cholinergic signs. Additional treatment, which included decontamination with enteral activated charcoal, intravenous fluid therapy, laxation and supportive care, as well as repeat administration of atropine, resulted in resolution of signs after 48 hours. A serum sample collected 30 hours after admission revealed that the total cholinesterase activity was reduced by 44 per cent, compared with a baseline value measured in a sample taken three weeks after the intoxication. This is the first report of human-prescribed pyridostigmine bromide intoxication in domestic cats.