Intraoperative acridine orange photodynamic therapy and cribriform electron-beam irradiation for canine intranasal tumors: A pilot study.

Untreated canine intranasal tumors carry a poor prognosis. We retrospectively evaluated the efficacy of marginal tumor resection in combination with intraoperative acridine orange (AO) photodynamic therapy (PDT) and 1 fraction of 5 Gy megavoltage irradiation for canine intranasal malignant tumors. When cribriform plate invasion or turbinate destruction around the cribriform plate was present, an additional fraction of 20 Gy was delivered with an electron beam during surgery. The study included 6 dogs, 2 of which were classified as stage I, 1 as stage II, and 3 as stage IV. The median local disease-free survival time and overall survival after the treatment were 8.5 and 13 months, respectively. Recurrence was noted in 2 of the 6 dogs after 4 and 7 months. Adverse events were mild (subcutaneous emphysema in 1 case, and rhinitis in 3 cases). Combination AO therapy may increase the tumor control time of dogs with marginally resectable intranasal malignant tumors.