A common upper respiratory tract disorder is rhinitis (inflammation of the mucous membranes of the nose) or other damage to the nasal mucous membranes. It is often associated with sinusitis, or inflammation of the lining of the sinuses. If the nasal passages deteriorate and fail to function properly, a major filtration function is removed. This exposes the lungs to much heavier loads of dust and micro-organisms.

Viral infection is the most common cause of acute rhinitis or sinusitis in cats. Feline herpesviral rhinotracheitis and feline calicivirus are most frequently involved (see Lung and Airway Disorders of Cats: Feline Respiratory Disease Complex (Feline Herpesviral Rhinotracheitis, Feline Calicivirus)). Infection with bacteria frequently occurs after the initial viral infection. Allergic rhinitis or sinusitis can occur seasonally (if due to pollen production) or year-round (if due to indoor allergens such as house dusts and molds). In cats, chronic nasal and sinus inflammation frequently occurs following severe acute viral infections of the nasal and sinus mucous membranes. Fungal nasal and sinus inflammation may be caused by the fungi Cryptococcus neoformans (relatively common in cats) or Aspergillus subspecies and Penicillium subspecies (both relatively rare in cats).

Signs of rhinitis include nasal discharge, sneezing, pawing at the face, snoring, open-mouth breathing, and labored inhalation. Tears and inflammation of the membrane surrounding the eyes (conjunctivitis) often accompany inflammation of the upper respiratory passages. The nasal discharge is clear but may become mucus-like as a result of secondary bacterial infection. Sneezing may be frequent, or it may come and go in cases of chronic rhinitis. Affected cats may also experience an aspiration reflex (“reverse sneeze”), a short rapid inhalation in an attempt to clear the nose.

Diagnosis is based on the cat's history, physical examination, radiographic findings (especially computed tomography), rhinoscopy, nasal biopsy, and elimination of other causes of nasal discharge and sneezing.

In mild or acute cases, treatment to relieve signs may be effective. Severe cases of rhinosinusitis in kittens or adult cats may require intravenous fluids to prevent dehydration, and nutritional support via a feeding tube to maintain weight. The veterinarian may prescribe antibiotics if secondary bacterial rhinosinusitis is present or suspected. (Antibiotics are not effective against viruses.) Feline herpesvirus vaccine (administered in the nose) occasionally may help shorten and minimize recurrence of signs of viral infection. In general, chronic rhinosinusitis is a frustrating disease to manage, and cures are rare. Fungal rhinosinusitis can be treated with antifungal therapy once the particular fungal cause has been identified. Surgery may be recommended for animals that do not respond to medical therapy, although the results are often disappointing.

Last full review/revision July 2011 by Ned F. Kuehn, DVM, MS, DACVIM; Stuart M. Taylor, PhD, BVMS, MRCVS, DECVP; Neil W. Dyer, DVM, MS, DACVP; Joe Hauptman, DVM, MS, DACVS