Postencephalitic epilepsy in dogs with meningoencephalitis of unknown origin: Clinical features, risk factors, and long-term outcome

Abstract

Background: Although the presence of seizures in dogs with meningoencephalitis of unknown origin (MUO) has been associated with shorter survival times, data regarding the prevalence and risk factors for postencephalitic epilepsy (PEE) is lacking. Objectives: To describe the clinical features, prevalence, risk factors, and long-term outcome of PEE in dogs with MUO. Animals: Sixty-one dogs with presumptive diagnosis of MUO based on the clinicopathological and diagnostic imaging findings. Methods: Retrospective study. Cases were identified by search of hospital medical records for dogs with suspected or confirmed MUO. Medical records of dogs meeting inclusion criteria were reviewed. Signalment, seizure history, clinicopathologic, and magnetic resonance imaging (MRI) findings were recorded. Results: Among 61 dogs at risk of PEE, 14 (23%) dogs developed PEE. Three of 14 dogs with PEE (21%) developed drug-resistant epilepsy. Dogs with PEE were younger (P =.03; ORadjusted = 0.75; 95% confidence interval [CI], 0.58-0.98) and had significantly shorter survival times (log-rank test P =.04) when compared to dogs that did not develop epilepsy. The risk factors associated with the development of PEE were the presence of acute symptomatic seizures (ASS; P =.04; ORadjusted = 4.76; 95% CI, 1.11-20.4) and MRI lesions in the hippocampus (P =.04; ORadjusted = 4.75; 95% CI, 1.07-21.0). Conclusions and Clinical Importance: Dogs with MUO and seizures at the early stage of the disease (ASS) seem to be at a higher risk of developing PEE.