Dr Thomas's Updates on Canine Epilepsy Research
From the ACVIM meeting in Charlotte NC June 2003
Zonisamide for seizures:
Curtis Dewey(1) presented an abstract on using zonisamide (Zonegran) in 12 dogs with epilepsy refractory to other drugs (mostly phenobarbital and bromide). Seven dogs (58%) had a decrease in the number of seizures after starting zonisamide, with a mean decrease in seizure frequency of 81%. In 8 of these dogs, it was possible to decrease the dose or withdraw concurrent anti-seizure drugs. Side effects were very mild.
Intranasal use of lorazepam:
Christopher Mariani(2)presented an abstract on the pharmacology of intranasal lorazepam in normal dogs. Lorazepam is a benzodiazepine that is normally administered by vein. It doesn't work well when given rectally because the liver inactivates most of the drug. They found that giving the drug into the nose bypasses the liver and obtains good blood levels. So this may prove to be an effective emergency treatment for seizures in situations where intravenous administration is not possible, such as treatment at home.
Genetics of idiopathic
epilepsy in the Vizsla:
MC Roberts(3) presented a poster describing a preliminary genome scan of Vizslas with idiopathic epilepsy. There results suggested an autosomal recessive mode of inheritance, although a polygenic mode could not be ruled out. Autosomal recessive means that a dog can seem normal yet be a carrier. If a breeding of seemingly normal dogs results in offspring with epilepsy, it means both parents are carriers. Polygenetic means that multiple genes are involved and the inheritance pattern can be complicated. They are doing follow up studies in an attempt to identify the responsible gene.
Cause of idiopathic epilepsy:
Denny O'Brien(4)presented a review of the causes of idiopathic epilepsy in dogs. Studies in humans have conclusively demonstrated genetic causes in certain type of epilepsy. Most of these involve mutations in ion channels in brain cells. Some of these are associated with abnormal ion channels. A high heritability has been documented in some canine breeds. The variability among different breeds suggests that different genes may be responsible in different breeds. In other words, it is unlikely that there is only one epilepsy gene in dogs, and there are probably different forms of epilepsy in different breeds.
1. Dewey CW et al. Zonisamide Therapy for Refractory Idiopathic Epilepsy in Dogs(abstract). 2003 ACVIM Forum Proceedings
2.Mariani CL, et al. A Comparison of Intranasal and Intravenous Lorazepam in Normal Dogs (abstract). 2003 ACVIM Forum Proceedings.
3.Roberts MC. Preliminary Genome Scan for Idiopathic Epilepsy in Purebred Vizsla Dogs (abstract).. 2003 ACVIM Forum Proceedings.
4.O'Brien D. Pathogenesis of Idiopathic Epilepsy. 2003 ACVIM Forum Proceedings
WB Thomas DVM,MS
University of Tennessee
Page last update: 12/13/2011