Mast cell tumours (MCTs) are the most common skin cancer in dogs, with a wide range of behaviour from benign to highly aggressive. Quality-of-life management alongside treatment is a central welfare consideration.
Mast cell tumour welfare encompasses both the disease itself and the side effects of treatment. The tumours can cause local pruritus (itching), swelling, and discomfort — high-grade tumours with systemic effects cause nausea, vomiting from gastric ulceration, and acute episodes of histamine release that may cause apparent shock-like episodes. Surgical treatment causes post-operative pain requiring appropriate analgesia. Chemotherapy and tyrosine kinase inhibitors cause variable side effects including gastrointestinal disturbance and myelosuppression. Quality-of-life monitoring throughout treatment allows dose adjustments that balance anti-tumour efficacy with welfare. For dogs with advanced disease, honest conversations about prognosis and quality of life — using validated tools — help owners make decisions that prioritise their dog's welfare over treatment for its own sake.