Efficacy of cobalt 60 radiotherapy in dogs with pituitary-dependent hyperadrenocorticism.

Abstract

OBJECTIVE:

To determine efficacy of cobalt 60 radiotherapy in dogs with pituitary-dependent hyperadrenocorticism (PDH) that have detectable tumors but no neurologic abnormalities.

DESIGN:

Case series.

ANIMALS:

6 dogs with PDH that had a detectable pituitary mass on magnetic resonance images.

PROCEDURE:

Radiation was delivered in 11 fractions during a 3.5-week period for a total dose of 44 Gy. Clinical signs were evaluated, a urinalysis and ACTH stimulation test were performed, and urine cortisol-to-creatinine ratio and plasma endogenous ACTH concentration were measured before, immediately after, and 1, 3, 6, 9, and 12 months after radiotherapy. Magnetic resonance imaging was repeated 1 year after radiotherapy.

RESULTS:

Clinical signs of hyperadrenocorticism resolved in 3 dogs but recurred in 2 of the 3. Clinical condition of 2 dogs improved but did not return to normal. One dog did not improve. Results of ACTH stimulation tests and urine cortisol-to-creatinine ratios correlated with clinical signs. Plasma endogenous ACTH concentration transiently decreased in all 6 dogs. One year after radiotherapy, size of tumors was decreased by 25% in 2 dogs; in the other 4 dogs, tumors could no longer be detected. None of the dogs developed neurologic abnormalities. Adverse effects of radiotherapy were mild.

CLINICAL IMPLICATIONS:

Radiotherapy did not result in adequate control of clinical signs of hyperadrenocorticism in 5 of 6 dogs, but size of pituitary tumors was dramatically reduced. Thus, it may be reasonable to recommend radiotherapy in dogs with PDH that have pituitary tumors for which greatest vertical height is 8 mm or more.

• Authors: M M Goossens, E C Feldman, A P Theon, P D Koblik
• Journal: Journal of the American Veterinary Medical Association (J Am Vet Med Assoc) Vol. 212 Issue 3 Pg. 374-6 (Feb 01 1998) ISSN: 0003-1488 [Print] United States
• PMID: 9470046 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Cobalt Radioisotopes

Topics

• Adrenocortical Hyperfunction (etiology, radiotherapy, veterinary)
• Animals
• Cobalt Radioisotopes (therapeutic use)
• Dog Diseases (etiology, radiotherapy)
• Dogs
• Female
• Magnetic Resonance Imaging (veterinary)
• Male
• Pituitary Irradiation (veterinary)
• Pituitary Neoplasms (complications, diagnosis)