Long-Term outcome following surgical excision of large, low to intermediate grade soft tissue sarcomas in dogs.

Introduction: Soft tissue sarcomas (STS) represent a heterogeneous group of tumours, with varying mesenchymal cell origin, size and histological grade. Large soft tissue sarcomas pose a surgical challenge due to feasibility of excision, and are often dismissed as good surgical candidates due to an anticipated poor prognosis.

Objective: To evaluate the long-term outcome of dogs that underwent surgical excision of large (≥5 cm), low to intermediate grade, soft tissue sarcomas.

Methods: Medical records of dogs that presented for STS excision between 2009 and 2021 were reviewed. Information was obtained regarding signalment, tumour location and size, preoperative cytology and histology, preoperative imaging, surgical findings, postoperative histological diagnosis and outcome. Dogs were included in the study if they underwent surgical excision of a de novo cutaneous or subcutaneous STS, which measured at least five centimeters in one plane, and was histologically diagnosed as low-intermediate grade. Long-term follow-up data were obtained via consultation, telephone or email.

Results: Thirty-nine dogs with large, low-intermediate grade STS were included. Most tumours were Grade 1 (28/39), located predominantly on the thigh and thorax (17/39). Tumours were removed by at least a narrow margin excision (≥1 cm) and deep fascial plane in all cases. Histological margins were deemed complete in 15/39, close (1-3 mm) in 8/39, incomplete in 4/39, and unknown in 12/39. All sites were closed primarily, either directly (22/39) or with flap reconstruction (17/39). Long-term follow-up (median 1064 days) reported good postoperative function, with owner reported local recurrence in 2/39. Minor complications occurred in 10/39 and major complications requiring surgical intervention occurred in 5/39.

Clinical Significance: Large, low-intermediate grade STSs can be surgically excised with good long-term function and outcome, where consideration is given to appropriate case selection and planning. If skin flap reconstruction is required, owners should be made aware of the possible complications associated with their use.

(© 2023 The Authors. Australian Veterinary Journal published by John Wiley & Sons Australia, Ltd on behalf of Australian Veterinary Association.)