Low-dose radiation therapy for idiopathic or interstitial cystitis in male cats

Idiopathic cystitis (IC) accounts for the majority of lower urinary tract (LUT) disease in cats and is characterized by recurrent clinical signs or urethral obstruction (UO), presenting ongoing challenges in clinical management.

Determine the feasibility of using single-fraction low-dose radiotherapy (RT) to reduce rate of re-obstruction and recurrence of clinical signs in cats with feline idiopathic cystitis.

Fifteen client-owned male cats with recent history of severe IC and historical UO that remained symptomatic despite environmental modification and pharmacological management.

An IACUC-approved, single-arm, single-institution, prospective clinical trial was conducted to evaluate the clinical effects of irradiating the entire LUT with a single 6 Gy fraction.

One cat was immediately lost to follow-up, and 1 died 516 days after RT. The remaining 13 cats were alive at the time of data analysis, with a median follow-up of 548 (range 70-1307) days. All but 1 had symptomatic improvement. Six had a single flare-up of signs of IC at a median of 243 days after RT (range 4-395 days). After RT, 1 cat had a recurrent UO, which occurred at 11 months and was managed surgically.

In this cohort of severely affected cats, >90% had apparent improvement in clinical signs after RT, with no documented adverse effects, demonstrating that in addition to environmental modification, RT is a promising tool for managing IC in male cats.