Feline Chronic Sinusitis Study Guide

Overview and Clinical Importance

Feline chronic rhinosinusitis (FCRS) is defined as inflammation of the nasal cavity and paranasal sinuses persisting for more than four weeks or recurring intermittently. This condition represents the second most common cause of feline nasal disease after neoplasia, accounting for approximately 35-55% of cases in referral settings. The disease is characterized by chronic, typically bilateral mucopurulent nasal discharge, sneezing, and stertorous breathing.

The pathogenesis involves initial viral damage, most commonly from feline herpesvirus-1 (FHV-1) or feline calicivirus (FCV), which leads to turbinate destruction and mucosal damage. This creates a self-perpetuating cycle of secondary bacterial infection, chronic inflammation, and further structural damage. Approximately 80% of cats experience neuronal latency of FHV-1 in the trigeminal ganglion, allowing viral reactivation during stress or immunosuppression.

Etiology and Pathophysiology

Primary Viral Etiology

Feline Herpesvirus-1 (FHV-1) is considered the common denominator initiating turbinate resorption. The virus causes epithelial necrosis and osteolysis of nasal turbinates through direct cytolytic effects. Following acute infection, FHV-1 establishes latency in the trigeminal ganglion, where it can reactivate during periods of stress, illness, or immunosuppression.