The utility of staging in canine mast cell tumours

Current staging of canine mast cell tumours (MCTs) practiced by many veterinarians involves a minimum of lymph node (LN) assessment, abdominal ultrasound and thoracic radiography. Historically, some have advocated buffy coat and bone marrow evaluation. Two hundred and twenty dogs with MCT seen at a referral clinic were staged using LN palpation/cytology, thoracic radiography and abdominal ultrasound. The utility of each method was evaluated by considering prevalence of spread and future behaviour. At presentation, 30.9% of dogs had metastases to the local LN; 6.8% of all the dogs also had distant metastases. No dog had or developed distant metastasis in the absence of LN metastasis. No dog had convincing evidence of pulmonary metastasis. In this series, the local LN was sentinel to metastasis and in the absence of local LN metastasis, the utility of further staging was low. Thoracic radiography was not useful in the staging of canine MCT.