Greater Swiss mountain dogs with idiopathic epilepsy in Germany : an investigation of the phenotype

Genetic predisposition of idiopathic epilepsy (IE) has been demonstrated
in individual breeds. According to the responsible breeding association
in Germany, the number of Greater Swiss Mountain Dogs (GS) with
seizures is increasing and nearly 3 % of registered dogs suffer from seizures.
In order to describe seizure phenotype and to examine seizure causes, a
questionnaire based study was performed. In cooperation with the Swiss
Mountain Dog Association of Germany e.V. (SSV e.V) we evaluated
112 questionnaires filled in by owners of GS showing seizures and by their
veterinarians between the years 2005 to 2021. Seizure characteristics, clinical
and further examinations, treatment, treatment response and pedigree
information were collected. IE was classified according to the International
Veterinary Epilepsy Task Force consensus proposal. 93 (83.06%) dogs had
IE (suspected genetic epilepsy) with confidence level I, II or III, the others
had structural epilepsy, reactive seizures or epilepsy of unknown cause. The
median age at seizure onset was 29.7 months. The most frequent seizure
type were focal seizures evolving into generalized ones (62.37%), often
starting with vomiting (n=38), retching (n=19) or salivation (n=19). Furthermore,
cluster seizures (CS) (49.46%) and status epilepticus (SE) (38.71%)
were observed in a substantial part of the cases. Forty (43.01%) dogs died
during the observation period, 34 (36.56%) have been euthanized (n=19) or
died spontaneously (n=15) during CS or SE. In GS idiopathic epilepsy presents
with a severe phenotype with frequently occurring CS and SE. This
study could serve as basis for further genetic evaluations.