Mast cell tumours are the most common cutaneous malignancy in dogs, and their variable biological behaviour makes welfare-conscious grading and treatment planning essential.
Mast cell tumours cause welfare suffering through local tumour effects, systemic mediator release causing GI discomfort and ulceration, and through the treatments required. Dogs with high-grade MCT undergoing chemotherapy experience treatment-related side effects including nausea, bone marrow suppression, and fatigue. GI ulceration from mast cell mediator release can cause significant abdominal pain if not proactively managed with H2 blockers or proton pump inhibitors. Welfare-conscious management includes proactive GI protection alongside tumour treatment, quality-of-life monitoring through treatment, and honest prognosis conversations that allow owners to make informed decisions about treatment intensity versus comfort-focused palliative care.