Canine limbal melanoma: 30 cases (1992-2004). Part 2. Treatment with lamellar resection and adjunctive strontium-90[beta] plesiotherapy - efficacy and morbidity

To evaluate the efficacy of lamellar resection and adjunctive ⁹⁰Sr-[beta] plesiotherapy in the management of canine limbal melanoma and the frequency and morbidity of early and late-onset side effects following treatment. Retrospective study. Thirty dogs treated for limbal melanoma at the Animal Health Trust (AHT), between 1992 and 2004. Medical records were reviewed and information collected on the radiation dose administered, duration of follow-up, and the frequency of early- and late-onset ocular side effects. Follow-up information was obtained by re-examination of patients or completion of a telephone interview with the referring veterinary surgeons or the owners. Recurrence of limbal melanoma occurred in 1 of 30 cases (3%; 95% CI: 0.2-14%). One or more side effects occurred in 16 of 30 cases (53%; 95% CI: 28.1-74.9). The occurrence of side effects was not associated with the number of sites treated or the total surface dose of radiation. Short-term side effects were reported in 16/30 cases (53%) and included corneal scarring (12/30), corneal neovascularization (6/30), conjunctivitis with or without granulation tissue formation (5/30), lipid keratopathy (1/30), and localized bullous keratopathy (2/30). Long-term side effects were reported in 6 of 30 cases (20%) cases and included deep scleral thinning (5/30), focal scleromalacia (3/30), globe perforation (2/30), lipid keratopathy (3/30), localized bullous keratopathy (1/30), and sectoral cortical cataract (1/30). Lamellar resection and adjunctive ⁹⁰Sr-[beta] plesiotherapy is relatively easy to perform, is minimally invasive, and extremely well tolerated by patients. The treatment is highly efficacious in the management of canine limbal melanoma. Modification of the radiation dosimetry, in particular reducing the total dose of radiation and the dose per radiation fraction, is necessary to reduce the incidence of late onset side effects.