Safety and Efficacy of Low-Dose Radiation Therapy for Feline Chronic Rhinitis

Presentation Description / Summary: Lymphoplasmacytic rhinitis is a common nasal disease of cats with unknown etiology. Treatment options are limited, and the disease is considered incurable. Given the inherent radiosensitivity of lymphocytes to ionizing radiation, low-dose radiation therapy was considered as a treatment option for cats with refractory disease. In this session we will review the components of a comprehensive diagnostic approach to feline chronic rhinitis, discuss a rational management plan for feline chronic rhinitis based on addressing clinical signs and morphologic alterations in the nasal mucosa, and describe the potential role for low-dose radiation therapy as a treatment option for feline chronic rhinitis.  Objectives of the study were to determine whether the use of low-dose radiation therapy causes a reduction in owner-reported clinical signs of chronic rhinitis, and to determine whether low-dose radiation therapy can be administered to patients without the development of short and long-term radiation therapy associated adverse effects. A prospective clinical trial recruited 11 cats with chronic lymphoplasmacytic rhinitis defined via clinical history, CT, rhinoscopy, tissue culture, and histopathology. Cats received 2 Gy/day on 3 consecutive days. Clinical efficacy was evaluated via owner-reported assessment using a severity of nasal inflammatory disease (SNIFLD) questionnaire modified for use in feline chronic rhinitis. Adverse effects were documented via examinations following each radiation treatment, owner follow-up, and recheck examinations at 1, 3, 6 and 12 months post treatment. All 11 cats successfully completed the treatment protocol and were available for 12-month follow-up. No cats exhibited acute adverse effects, and 1 cat developed subtle leukotrichia approximately 6-months post treatment. Ten of 11 cats showed improvement of owner-reported quality of life scores and clinical signs at 1- and 3-months post treatment. In most cats, clinical signs returned to pre-treatment baseline by 6-months post treatment. Radiation therapy is a potentially safe and effective modality for feline chronic rhinitis that warrants further investigation.