Objective—To determine concentrations of excitatory
and inhibitory amino acids in CSF of a large number
of dogs with idiopathic epilepsy or genetic epilepsy
and to evaluate changes in CSF amino acid concentration
with regard to drug treatment and sex.
Animals—35 Labrador Retrievers with genetic
epilepsy (20 male and 15 female), 94 non-Labrador
Retrievers with idiopathic epilepsy (71 male and 23
female), and 20 control dogs (10 male and 10 female).
Procedure—Collection of CSF was performed > 72
hours after the occurrence of seizures. Cerebrospinal
fluid concentrations of γ-aminobutyric acid (GABA),
glutamate (GLU), aspartate (ASP), serine, and glycine
were determined by use of high performance liquid
chromatography with electrochemical detection.
Results—CSF concentrations of GABA and GLU
were significantly lower in Labrador Retrievers
with genetic epilepsy (LR-group dogs) than in control-group dogs or in non-Labrador Retrievers with
idiopathic epilepsy (non–LR-group dogs). The GLU-to-GABA ratio was significantly higher in LR-group
dogs than in non–LR-group dogs. CSF concentrations
of GLU and ASP were significantly lower
when all dogs with epilepsy (non–LR- and LR-group
dogs combined) were compared with control-group dogs.
Conclusions and Clinical Relevance—A decrease in
CSF concentrations of GABA appears to play a role in
the pathogenesis of genetically determined epilepsy
in Labrador Retrievers. However, this decrease in CSF
concentrations of GABA may also be a consequence
of seizure activity. The GLU-to-GABA ratio may prove
to be a useful indicator of genetic epilepsy in Labrador
Retrievers. (Am J Vet Res 2004;65:1108–1113)