Zonisamide has been contraindicated for use in dogs with a hypersensitivity to sulfa drugs. Dogs that are pregnant should not take zonisamide, as this drug can lead to birth defects. Taking zonisamide with hepatic enzyme inhibitors can increase the metabolism and clearance of the anticonvulsant, but the actual clinical significance of this reaction is still unknown. Zonisamide is not to be used in cats.
While the use of zonisamide in pets has not been studied extensively, a few side effects have been noted. Sedation and ataxia are the two most notable side effects, however in some rare cases, skin reactions, blood dyscrasias, and hyperthermia have also been reported.