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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
Dipl.ACVIM(Neurology)
University of Tennessee
Page last update: 12/13/2011
