Written By Mel Lee-Smith
Published: 09/15/2020Updated: 08/30/2021
Zonisamide for Dogs | Wag!

Zonisamide for dogs is an anticonvulsant medication used to control seizures. It’s an alternative option to drugs like phenobarbital for treating dogs with epilepsy and other seizure disorders.

Zonisamide is a prescription medication that may be combined with other medications. If your vet has prescribed zonisamide for your dog, keep reading to find out all about the recommended dosage amount, efficacy, side effects, and drug interactions.


Zonisamide is available as an oral capsule or a liquid. The recommended dosage amount for the treatment of seizures is between 5 mg and 10 mg/kg, given orally every 12 hours. Your vet will determine the best dosage amount for your dog based on their diagnosis, overall health, and how they respond to the medication.

Dosage instructions

Administer zonisamide according to your vet’s instructions. Your dog can take zonisamide on an empty stomach or with food. It’s also important to make sure your pet has access to an ample supply of fresh water.

You should never stop giving zonisamide abruptly as seizures may occur. If the drug has an adverse effect on your dog, your veterinarian will advise you on the best course of action. Your veterinarian may also request blood level monitoring while your pet is receiving zonisamide.


Zonisamide for dogs helps control seizures on its own or in combination with other medications. While the exact action of the medication isn’t fully known, it’s thought to reduce seizures by blocking sodium channels in the brain.

Studies show that zonisamide suppresses maximal electroshock seizures in dogs, mice, rats, and rabbits. It’s also relatively well tolerated by dogs, but it can have a mild effect on the liver when chronically administered at a high dose level of 75 mg/kg.

Information on the clinical efficacy of zonisamide in dogs with epilepsy is limited to 3 small open‐label, uncontrolled studies. One study showed that 60% of dogs treated with zonisamide responded favorably, showing a minimum 50% reduction in the monthly frequency of seizures. Of the other 4 dogs in the study, 2 did not have a reduction in seizures and the other 2 experienced an increase in the frequency of seizures.

When combined with other antiepileptic medications, zonisamide is 58% to 80% effective at decreasing seizure frequency by at least 50%.

Side effects

Zonisamide for dogs may cause the following side effects:

Rarely, the medication may also cause liver damage, so monitor your pet for yellowing of the skin, gums, or the whites of the eyes. Report any side effects to your vet.


Just like any other medication, zonisamide for dogs may interact with other drugs your dog is taking. It also may not be suitable to give to dogs with specific health issues, so your vet will need to examine your pet and have the full details of their medical history before prescribing zonisamide.

Drug interactions

Zonisamide for dogs may interact with phenobarbital. Concurrent use of phenobarbital may cause zonisamide to be metabolized at a faster rate. As a result, dogs who are also taking phenobarbital may be prescribed a higher dose of zonisamide.

Other drugs may interact with zonisamide, so make sure you inform your vet of all medications (including herbs, vitamins, and supplements) that your pet is currently taking.

Allergic reactions and sensitivity

Never give zonisamide to pets who are allergic to it or other sulfonamide drugs. The medication is also not safe for pregnant dogs as it can cause cardiovascular damage in unborn puppies. Do not give zonisamide to nursing dogs or those with liver disease.

Frequently asked questions

Does my pet need a prescription to be given zonisamide?

Yes, zonisamide for dogs is a prescription medication.

What should I do if my pet has an adverse reaction to zonisamide?

If your pet has an overdose of zonisamide or experiences an adverse reaction to the medication, seek veterinary medical attention for your dog immediately.

My dog is taking zonisamide but their seizures are getting worse. What should I do?

Don’t stop treatment unless your vet explicitly instructs you to do so. If you’re unsure whether zonisamide is working, consult your vet for alternative treatment options.

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