Treatment options and results for dog eye melanoma surgery

Abstract

OBJECTIVE: To evaluate the efficacy and complication rate of partial lamellar resection followed by cryotherapy for the management of canine limbal melanoma. ANIMALS STUDIED: Fourteen dogs with unilateral canine limbal melanoma which were managed surgically by partial lamellar resection, cryotherapy (1,1,1,2-tetrafluoroethane) and an adjunctive graft procedure. METHODS: The clinical records of dogs treated between June 1998 and June 2008 were reviewed. The signalment, approximate size and location of the melanoma, variation in surgical technique, recurrence rate, short-term (< three months) and long-term (> three months) complications were assessed. Follow-up information was collected by patient re-examination or telephone interview. RESULTS: The mean age at diagnosis was 6.3 years, with a range from 3.2 to 12 years. Seven breeds were affected, including five cross-breed dogs and four Golden Retrievers. The tumour involved the dorsal arc (from the dorsomedial to the ventrolateral quadrant) in 12 eyes and the ventral arc in two eyes. The size of the tumour ranged from 30 to 180 degrees of the limbal circumference. A double freeze-thaw cycle of cryotherapy was performed in 7/14 eyes and a triple freeze-thaw cycle in 7/14 eyes. An adjunctive conjunctival graft was performed in 13/14 eyes (free graft n = 3, posterior nictitans conjunctiva/cartilage n = 4, advancement graft n = 5, small intestinal submucosa/advancement graft n = 1) and a frozen homologous graft in 1/14 eyes. The duration of follow-up ranged from 6 months to 8.5 years with a median of 2.1 years. Recurrence was not clinically detected in any of the 14 eyes. Early complications occurred in 8/14 eyes and included anterior uveitis (7/14), corneal ulceration (5/14), marked corneal granulation tissue at the graft margin (2/14), dyscoria (2/14), corneal lipidosis (1/14) and corneal oedema (1/14). Intra-operative globe perforation had occurred in 5/7 eyes with anterior uveitis and 2/2 eyes with transient dyscoria. Late complications occurred in 3/14 eyes and included corneal lipidosis which was either mild (< 2mm in diameter, 1/14) or marked (>1cm in diameter, 2/14). Marked lipidosis only occurred following the treatment of extensive limbal melanomas which involved approximately 50% of the limbal circumference. CONCLUSIONS: Surgical management comprising partial lamellar resection, cryotherapy and adjunctive graft placement is technically straightforward, minimally invasive, well tolerated and highly effective. Marked corneal lipidosis is most likely to occur as a post-operative complication when the limbal melanoma is extensive.