Zonisamide for Pets

Anti Seizure Medication for Animals

What is Zonisamide?

Zonisamide may be prescribed for hard to treat seizures or epilepsy. Zonisamide works by preventing the spread of the seizures and decreasing the excessive amount of neuronal firing.

Seizures are among the most common neurological issues affecting animals.

Seizures are brief disturbances in brain function that cause behavioral changes in response to an abnormal event in the central nervous system. Epilepsy is a syndrome of recurrent, spontaneous seizures. Seizures are serious and can be life threatening. It is important to have a proper diagnosis prior to starting drug therapy to prevent and control these events.

When your animal is having a seizure it might be difficult to directly determine what is happening. Animals can present with strange behaviors that can include vomiting, restlessly pacing around, and becoming stiff and collapsing onto the ground, or appearing dazed and confused. It is important to talk with a veterinary to determine what is the best way to go about treating the animal.

Zonisamide is a newer option that can be used alone or in combination with other seizure drugs to control the animal’s neurological condition.

Causes of Seizure Disorder in Animals

• Structural Abnormalities - Tumors in the brain, neurodegenerative diseases, stroke, and traumatic brain injury
• Other Conditions - Emotional distress, change in routine, estrous cycle, altered sleep patterns, visitors at home
• Idiopathic - Recurring chronic seizures, which appear to have no underlining cause
• Infection - Commonly seen with parasitic infections, and other infectious diseases

Side Effects Commonly Seen With Zonisamide:

• Dogs: Sedation, ataxia, loss of appetite
• Cats: Sedation, ataxia, anorexia, vomiting, diarrhea

How Can Zonisamide Help?

Zonisamide is a newer, second-generation antiepileptic drug. It works by blocking voltage gated sodium channels, inhibiting T-type calcium channels, and enhancing release of neurotransmitters. This mechanism ultimately helps control seizure activity by decreasing the over-activity of nerve cells in the brain and preventing them from abnormal firing.

For treatment of seizure, zonisamide can be used as monotherapy alone or can be added on to other anti-convulsants for harder to treat refractory cases. A veterinarian should determine the proper dose of the medication for the animal, but typically doses ranges from 5-10mg/kg taken orally.

Zonisamide can be an option when other anti-seizure medications are not well tolerated or causing unwanted side effects. As zonisamide is a second-generation seizure drug, it has less interaction liability with other medications that the animal may be taking. This drug should not be used inpets that are allergic to zonisamide or are hypersensitive to sulfonamide drugs. Also zonisamide should be avoided in animals that are breeding, pregnant, or that have liver disease.

Other Options Available for Seizure Disorder in Animals

• Phenobarbital
• Potassium Bromide
• Primidone
• Levetiracetam

Zonisamide Dosing Forms

Zonisamide is only commercially available as oral capsules, which may be difficult for animals to consume.

If interested you can contact a specialty compounding pharmacy to have zonisamide made into flavored soft chews, in addition to flavored suspensions, and capsules in specific strengths for your pet.

References

• Forsgård, JA, Metsähonkala, L, Kiviranta, A-M, et al. Seizure-precipitating factors in dogs with idiopathic epilepsy. J Vet Intern Med. 2019; 33: 701– 707. https://onlinelibrary.wiley.com/doi/10.1111/jvim.15402
• Muñana, K.R. Seizure Management in Small Animal Practice. Veterinary Clinics: Small Animal Practice. 2013; 43 (5): 1127 – 1147 https://www.vetsmall.theclinics.com/article/S0195-5616(13)00113-7/fulltext
• Partridge B, Rossmeisl Jr J.H. Companion animal models of neurological disease. Journal of Neuroscience Methods. 2019; 331 https://www.sciencedirect.com/science/article/pii/S0165027019303413?via%3Dihub
• Podell, M., Volk, H., Berendt, M., Löscher, W., Muñana, K., Patterson, E. and Platt, S. (2016), 2015 ACVIM Small Animal Consensus Statement on Seizure Management in Dogs. J Vet Intern Med, 30: 477-490. https://onlinelibrary.wiley.com/doi/full/10.1111/jvim.13841
• Zonisamide. Lexi-Drugs. Lexicomp. Wolters Kluwer Health, Inc. Riverwoods, IL.