Clinical characterization of epileptic seizures in Pomeranians with idiopathic epilepsy or epilepsy of unknown cause.

Background: Focal epileptic motor seizures manifested by limb contraction have been recognized anecdotally in Pomeranians.

Objectives: To investigate clinical features of idiopathic epilepsy (IE) and epilepsy of unknown cause (EUC) in Pomeranians as well as the ADAM23 haplotype frequency previously reported as a common risk haplotype for epilepsy in several breeds of dogs.

Animals: Twenty-eight Pomeranians, including 15 with IE and 13 with EUC. Nine Pomeranians with epilepsy and 8 control Pomeranians were used for ADAM23 risk haplotype analysis.

Methods: Case series study including both retrospectively and prospectively collected cases. The ADAM23 haplotype was determined by direct sequencing of PCR amplicons. Data were analyzed descriptively.

Results: Focal epileptic seizures (FS) were the predominant type of seizure in 22 of 28 dogs (78.6%). Among these, 12 of the IE dogs (80.0%) and 10 of the EUC dogs (76.9%) showed FS. Notably, 21 of 22 Pomeranians with FS (95.5%) showed limb contraction during ictal periods. Some dogs with FS also showed immobility, generalized tremors, difficulty walking or moving, autonomic signs, orofacial automatisms or some combination during ictal events. Ten dogs with FS and limb contraction had electroencephalography (EEG) performed, and interictal epileptiform discharges were identified in 9 dogs. The haplotype frequency of ADAM23 in cases was lower (27.8%) than that of the controls (56.3%).

Conclusions And Clinical Importance: In our study, FS was the predominant type of seizure in Pomeranians, and almost all cases with FS showed limb contraction, regardless of whether having IE or EUC.