Radiation therapy (RT) for the treatment of soft tissue sarcomas and mast cell tumors is increasingly available to veterinarians and pet owners. One of the complications that limits treatment is the development of radiation-induced dermatitis (RID). The clinical signs of RID can vary from mild erythema, scaling, and pruritus to severe desquamation, ulceration, and necrosis. Glucocorticoids are commonly used to treat this side effect; however, there are no controlled studies documenting its effectiveness. In this double-blind, randomized, placebo-controlled prospective study, 22 dogs received either oral prednisone (0.5 mg/kg) or placebo once daily during a 36-day treatment period. All dogs received the same RT dose 2 weeks after surgical excision of the primary tumor. The dogs were examined and scored for lesion severity weekly throughout the study. Skin biopsies were obtained on day 15 and day 36 of the study. There was no difference between the prednisone and placebo groups with respect to development of secondary bacterial infections; 21 of 22 dogs required antibiotic therapy. Yeast dermatitis was found in 10 of 22 dogs. Clinical and histologic examination found no difference between the 2 treatment groups.

COMMENTARY: Although prednisone has commonly been used in an attempt to reduce the complication of radiation burns, this study showed it wasn't helpful. However, the agent may have a role in pain control, so more studies need to be done before a recommendation against its use can be made.

The clinical and histopathological effects of prednisone on acute radiation-induced dermatitis in dogs: A placebo-controlled, randomized, double-blind, prospective clinical trial. Flynn AK, Lurie DM, Ward J, et al. Vet Dermatol 18:217-226, 2007.