Seizure disorders can develop in association with a variety of intracranial or extracranial disease processes in companion animals.
Extracranial causes of seizures include metabolic or biochemical imbalances associated with altered organ function (ie. effects of ammonia in liver failure patients) or due to exposure to seizurogenic toxins.
Intracranial causes of seizures include structural abnormalities (ie. tumor or scarring after head trauma or other insult), as well as functional disturbances that result in neuronal hyperexcitability. Idiopathic epilepsy is one example of a functional disturbance in which there is an imbalance between normal excitatory and inhibitory mechanisms.
Primary idiopathic epilepsy is estimated to affect up to 5% of the canine population. It can present in a variety of breeds, and age of onset is typically young - 6 months up to 5 or 6 years of age.
Anticonvulsant therapy is the mainstay of treatment for patients with idiopathic epilepsy. The goal of therapy is to reduce the frequency and severity of seizures, as complete resolution of seizure activity or cure is unlikely. Lifelong daily treatment is required in these patients, and some drugs have side effects that can affect patient morbidity and quality of life.
Phenobarbital and Potassium Bromide are two of the most commonly used anticonvulsant drugs for treating dogs with idiopathic epilepsy. In addition to the undesired side effects they can cause, including sedation and paresis, up to 15-30% of patients may fail to respond to these drugs - whether used alone or in combination. Zonisamide and levetiracetam are two other drugs available to clinicians for long term management of seizures.
Levetiracetam has been shown to be safe and effective in dogs, all the while causing minimal side effects - even at high doses. Based on the results of previous studies, TID (every 8 hour) dosing has been recommended to ensure adequate therapeutic levels.
Client compliance is one of the biggest challenges that clinicians face when recommending treatment for any medical problem. The reality is that many pet owners are hard pressed to adhere to a TID administration of any treatment for their pet. In the case of a seizure disorder, noncompliance in administering an anticonvulsant has serious consequences for the pet.
An extended release formulation of levetiracetam (Keppra ER) is available for managing epilepsy in humans, and it is administered once to twice daily.
The subject of this week's Evidence Based Update is anticonvulsant therapy - with an emphasis on this particular drug. Discussion includes:
View this Evidence Based Update (Running time 14 mins; Approved for CE credit in New York and by the NJVMA, pending approval for CE credit by AAVSB RACE).
We've recently added a new article to the Pet Health Information Library - please use this as a resource for your clients on understanding Seizures in Dogs and Cats.
