Safety and efficacy of intralesional triamcinolone administration for treatment of mast cell tumors in dogs: 23 cases (2005-2011).

OBJECTIVE To evaluate the safety and efficacy of intralesional triamcinolone administration, as a sole or adjuvant treatment, in dogs with mast cell tumors. DESIGN Retrospective case series ANIMALS 23 dogs with mast cell tumors. PROCEDURES Medical records of dogs treated for a confirmed diagnosis of a mast cell tumor between 2005 and 2011 were reviewed. Patients with a confirmed diagnosis and measurable disease (tumor longest dimension ≥ 0.5 cm) that had received ≥ 1 intralesional treatment with triamcinolone, regardless of prior, concurrent, or adjuvant treatments, were eligible for inclusion. Data collected included patient characteristics, results of cytologic and histologic testing and tumor staging, triamcinolone dosage, treatment response, and adverse events. RESULTS 23 dogs with 24 tumors were included. Tumors were treated by means of intralesional triamcinolone administration alone (n = 5), intralesional triamcinolone administration with concurrent oral administration of glucocorticoids (6), and intralesional triamcinolone administration with concurrent cytotoxic chemotherapy, with or without oral administration of corticosteroids and radiation therapy (13). Of 5 dogs treated with intralesional triamcinolone administration alone, 1 achieved a complete response, 3 achieved a partial response, and 1 maintained stable disease. The response rate for all 24 tumors (23 dogs) was 67% (16/24), including 4 with a complete response and 12 with a partial response. The median time to progression was 63 days (range, 6 to 447 days). Three dogs experienced adverse events (local hemorrhage [n = 1]; suspected gastrointestinal ulceration [2]). CONCLUSIONS AND CLINICAL RELEVANCE Intralesional triamcinolone administration may be well tolerated and effective for treatment of nonresectable mast cell tumors in dogs.