Survival, Neurologic Response, and Prognostic Factors in Dogs with Pituitary Masses Treated with Radiation Therapy and Untreated Dogs

Abstract

Background: Pituitary masses in dogs are not uncommon tumors that can cause endocrine and neurologic signs and, if left untreated, can decrease life expectancy.Hypothesis: Dogs with pituitary masses that received radiation therapy (RT) have more favorable neurologic outcomes and longer survival times compared with untreated dogs.Animals: Nineteen dogs with a pituitary mass identified on CT or MR imaging were irradiated with 48 Gy given in 3 Gy daily‐dose fractions. Twenty‐seven untreated control dogs had pituitary masses.Methods: Medical records of dogs with pituitary masses were retrospectively reviewed for clinical signs, mass size, and outcome.Results: Median survival time was not reached in the treated group. Mean survival time in the treated group was 1,405 days (95% confidence interval [CI], 1,053–1,757 days) with 1‐, 2‐, and 3‐year estimated survival of 93, 87, and 55%, respectively. Median survival in the nonirradiated group was 359 days (95% CI, 48–916 days), with a mean of 551 days (95% CI, 271–829 days). The 1‐, 2‐, and 3‐year estimated survival was 45, 32, and 25%, respectively. Dogs that received RT for their pituitary tumors had significantly longer survival times than untreated dogs (P =.0039). Treated dogs with smaller tumors (based on maximal pituitary‐to‐brain height ratio or area of tumor to area of brain) lived longer than those with larger tumors (P <.001).Conclusions and Clinical Importance: When compared with untreated dogs, RT increased survival and controlled neurologic signs in dogs with pituitary masses.