Immune-mediated polyneuropathy in cats: Clinical description, electrodiagnostic assessment, and treatment.

Background: Suspected immune-mediated polyneuropathy has been increasingly reported in cats, especially in the last decade, but the condition remains poorly understood.

Objectives: Refine the clinical description and review the classification of this condition based on electrodiagnostic investigation and evaluate the benefit of corticosteroid treatment and L-carnitine supplementation.

Animals: Fifty-five cats presented with signs of muscular weakness and electrodiagnostic findings consistent with polyneuropathy of unknown origin.

Methods: Retrospective, multicenter study. Data from the medical records were reviewed. The owners were contacted by phone for follow-up at the time of the study.

Results: The male-to-female ratio was 2.2. The median age of onset was 10 months, with 91% of affected cats being <3 years of age. Fourteen breeds were represented in the study. The electrodiagnostic findings supported purely motor axonal polyneuropathy. Histological findings from nerve biopsies were consistent with immune-mediated neuropathy in 87% of the tested cats. The overall prognosis for recovery was good to excellent, as all but 1 cat achieved clinical recovery, with 12% having mild sequelae and 28% having multiple episodes during their lifetime. The outcome was similar in cats with no treatment when compared with cats receiving corticosteroids or L-carnitine supplementation.

Conclusions And Clinical Importance: Immune-mediated motor axonal polyneuropathy should be considered in young cats with muscle weakness. This condition may be similar to acute motor axonal neuropathy in Guillain-Barré syndrome patients. Based on our results, diagnostic criteria have been proposed.