Cutaneous Adverse Drug Reactions in Dogs Treated with Antiepileptic Drugs

Abstract

Epilepsy is one of the most common neurologic disorders in dogs and life-long treatment with antiepileptic drugs (AED) is frequently required. Adverse events of AED targeting the skin are only rarely reported in veterinary medicine and the true incidence and spectrum of cutaneous reactions in epileptic dogs remains unknown. In this study, we hypothesized that cutaneous reactions commonly occur in epileptic dogs and are related to AED treatment. A retrospective case review of 185 dogs treated for epilepsy identified 20.0% with simultaneous appearance of dermatologic signs. In a subsequent prospective case investigation (n = 137), we identified newly appearing or distinct worsening of skin lesions following initiation of AED therapy in 10.9% of dogs treated for epilepsy (95% CI 6.8–17.7%). Cutaneous lesions were classified as probably drug-induced in 40.0% of these cases. Patch testing and intradermal testing were further investigated as potential diagnostic methods to confirm AED hypersensitivity. They were of high specificity but sensitivity and positive predictive value appeared inappropriate to recommend their routine use in clinical practice.

Suspected phenobarbital-induced fever in a cat

“…Similar reports of anticonvulsant-related syndromes have been reported in dogs and cats, as well as other hematologic and biochemical abnormalities. 5–9 Pseudolymphoma secondary to phenobarbital administration has been reported in one dog and two cats, characterized by fever and generalized lymphadenopathy that resolved after discontinuation of the medication. 10–12 A recent report of similar signs in a cat occurred during treatment with multiple anticonvulsants and resolved after discontinuation of zonisamide.…”