Cerebrospinal fluid (CSF) abnormalities after seizure activity have been anecdotally reported in veterinary medicine, but have not been well described. In human medicine, seizures are reported to induce postictal CSF pleocytosis and increased protein levels. The aims of this study were to determine if seizures induce CSF abnormalities in dogs and under what conditions they occur.

The medical records of dogs presented to the University of Glasgow Small Animal Hospital, from January 2003 to July 2007, for investigation of seizures and diagnosed with idiopathic epilepsy were reviewed retrospectively. Criteria for inclusion were: CSF analysis (including a manual cell count); advanced brain imaging; information on the number and time interval between the last seizure event(s) and CSF sample collection; CSF red cell count <4000 RBC/μL. For statistical analysis the cases were divided into 3 groups based on the time interval between the last seizure event(s) and CSF sample collection: less than 48 hours; between 2 and 7 days; greater than 7 days.

One hundred and twenty five dogs met the inclusion criteria. In 27 dogs CSF collection was performed less than 48 hours after the last seizure, in 34 dogs CSF collection was performed between 2 and 7 days after the last seizure and in 64 dogs CSF collection was performed more than 7 days after the last seizure. In 40 dogs the seizure episode prior to CSF collection was recorded as cluster seizures.

CSF analysis revealed abnormalities in 8 (6.4%) cases. Pleocytosis was identified in 4 (3.2%) cases and the protein concentration was abnormally elevated in 5 (4.4%) cases. Neither the time interval between the last seizure and CSF sample collection nor the occurrence of cluster seizures was significantly associated with the probability of detecting CSF abnormalities. Nonetheless, a statistically significant association was demonstrated between the time interval between the last seizure and the CSF leukocyte count: the longer the interval the lower the cell count (P = 0.034). The same was not found in relation to the protein concentration.

The findings of the study suggest that CSF pleocytosis may be induced by seizures. However, given the low incidence of this finding and the possibility that seizure frequency might be related to seizure aetiology, all patients with abnormal CSF findings should be thoroughly evaluated for central nervous system disease before these changes are attributed to seizure activity alone.