Generalised absence seizures in Cavalier King Charles Spaniels presenting with paroxysms: eight cases (2016-2025)

To describe the clinical and electroencephalographic findings associated with absence seizures in a population of Cavalier King Charles Spaniels.

This was a retrospective descriptive case series of Cavalier King Charles Spaniels diagnosed with absence seizures at two veterinary referral hospitals between 2016 and 2025, whereby at least one ambulatory video-electroencephalography study was available.

Data from eight dogs were included for review. The mean video-electroencephalography study duration was 373 minutes (range 7 to 1783). All dogs showed ictal discharges characterised by generalised onset, 3 to 4 Hz, spike-and-wave complexes with a caudal midline dominance, consistent with the current electrographic definitions of absence seizures in human medicine. Ictal discharges were time-locked to myoclonus (5/8, 62.5%), behavioural arrest (3/8, 37.5%) or of ≥10 seconds without motor manifestations (4/8, 50.0%). Following treatment with anti-seizure medication, a reduction in paroxysm frequency by ≥50% was reported by caregivers of 5/6 (83.3%) dogs, with 4/4 (100%) demonstrating improved ictal discharge severity on follow-up video-electroencephalography. One dog was hospitalised due to poor absence seizure control and ultimately euthanased despite inpatient treatments. Although fly catching was a primary complaint in two dogs, it was only captured in one, being time-locked to beta-background activity.

This is the first case series reporting generalised absence seizures as an electroclinical syndrome in Cavalier King Charles Spaniels that is consistent with the current electrographic definition of absence seizures in human medicine.