• Open Access

Linear-Accelerator-Based Modified Radiosurgical Treatment of Pituitary Tumors in Cats: 11 Cases (1997–2008)


  • A portion of this work was presented at the 23rd Annual Veterinary Cancer Society Conference, September 26–29, 2003, Madison, WI. Work was performed at Washington State University.

Corresponding author: Dr Janean Fidel, Department of Veterinary Clinical Sciences, Washington State University, PO Box 7060, Pullman, WA 99164; e-mail: jfidel@vetmed.wsu.edu.


Objective: Determine the efficacy and safety of a linear-accelerator-based single fraction radiosurgical approach to the treatment of pituitary tumors in cats.

Design: Retrospective study.

Animals: Eleven client-owned cats referred for treatment of pituitary tumors causing neurological signs, or poorly controlled diabetes mellitus (DM) secondary either to acromegaly or pituitary-dependent hyperadrenocortism.

Procedures: Cats underwent magnetic resonance imaging (MRI) of the brain to manually plan radiation therapy. After MRI, modified radiosurgery was performed by delivering a single large dose (15 or 20 Gy) of radiation while arcing a linear-accelerator-generated radiation beam around the cat's head with the pituitary mass at the center of the beam. Eight cats were treated once, 2 cats were treated twice, and 1 cat received 3 treatments. Treated cats were evaluated for improvement in endocrine function or resolution of neurological disease by review of medical records or contact with referring veterinarians and owners.

Results: Improvement in clinical signs occurred in 7/11 (63.6%) of treated cats. Five of 9 cats with poorly regulated DM had improved insulin responses, and 2/2 cats with neurological signs had clinical improvement. There were no confirmed acute or late adverse radiation effects. The overall median survival was 25 months (range, 1–60), and 3 cats were still alive.

Conclusions and Clinical Importance: Single fraction modified radiosurgery is a safe and effective approach to the treatment of pituitary tumors in cats.