Transient hyperammonaemia following epileptic seizures in cats

Abstract

Objectives The aim of this study was to determine whether transient postictal hyperammonaemia exists in cats. Methods The medical records of all feline patients that presented at a Swedish veterinary hospital between 2008 and 2018 were retrospectively reviewed to find those that had a recent or ongoing epileptic seizure. To qualify for inclusion, the medical record had to include information on at least one ammonia value taken in close proximity to, or during, an active seizure, the cat must have exceeded the normal upper limit of blood ammonia concentration on initial testing (reference interval 0–95 μmol/l), and there needed to be a follow-up ammonia value available within a maximum of 3 days. Results Five cats were included in the study, and they had blood ammonia concentrations on initial testing ranging from 146 to 195 µmol/l. They were all retested within a period of 2 h to 3 days of the original reading. All five cats had a spontaneous decrease in ammonia levels without any specific treatment for hyperammonaemia. Conclusions and relevance Pursuant to the findings of this retrospective study, transient hyperammonaemia may be noted after epileptic seizure in cats. Consequently, a differential diagnostic list in feline patients with hyperammonaemia could, depending on the context, include non-hepatic-related pathologies, such as epileptic seizures.

Management of status epilepticus in dogs

“…A full discussion of management of this condition is outside the scope of this article. Also of note, high ammonia levels can be seen in cats after a recent seizure event (Nilsson and others 2021). If no other indications of portosystemic shunt are present, ammonia should be retested after 24 to 48 hours. ▪ Antiseizure drug serum levels (eg, serum phenobarbital levels and KBr) should also be submitted for measurement to inform further therapeutic decisions in patients already receiving these medications.…”