Canine conjunctival mast cell tumors: a retrospective study

To describe signalment, clinical presentation, treatment, recurrence rate, and outcome of canine conjunctival mast cell tumors (MCTs).

Retrospective study.

Canine cases were selected from the Comparative Ocular Pathology Laboratory of Wisconsin, Eye Path Lab of the UK, and California Eye Care for Animals. Thirty-two canine patients were identified as having a MCT presumed to be arising primarily from the conjunctiva. Data were collected from pathology submission request forms; additional information was collected by means of a questionnaire distributed to the veterinary ophthalmologist or veterinarian who performed the surgery. Data collected included age, gender, breed, location of tumor, dimensions of tumor, duration and growth rate, additional diagnostics, surgical descriptions, adjunctive treatment, histologic description, special stains, number of recurrences, and final outcome.

Thirty-two dogs with 33 conjunctival MCTs meeting search criteria were identified. All dogs underwent surgical excision as the primary treatment. Surgical margins were evaluated for 30 tumors and were reported as: incomplete margins in 25 cases, narrow in four cases and complete in one case. Histologic grade was provided for 33 of 33 MCTs and included 10 low (30%), 18 intermediate (55%) and five high-grade (15%) tumors. Follow up information was received for 25 dogs. Four died of unrelated causes, two had local recurrence, 15 were currently disease free (mean 21.4 months postoperatively) and four were reported to be disease free at the reported rechecks but were lost to long term follow up (mean 13 months postoperatively). No dogs in the study were identified that died of MCT related disease.