This study does not report that that layer V cortical neurons are missing a particular ion channel. They examine currents through HCN and voltaged-gated potassium channels and find differences in the total current carried that depends on species.

In general, epileptic disorders are observed across species. It's common in dogs, for instance: https://www.akcchf.org/canine-health/top-health-concerns/epi...

A ton of papers examining ion channel expression in epilepsy that should be more relevant: https://pubmed.ncbi.nlm.nih.gov/?term=human+ion+channel+epil...