Mast cell tumours (MCTs) are one of the most common skin cancers in dogs. They arise from mast cells, which are immune cells involved in allergic reactions. MCTs can occur in any breeds, but Boxers, Boston Terriers, Labrador Retrievers, Bulldogs, Shar Peis and Pugs have increased risks.
Specialist in Veterinary Oncology Dr. Katrina Sun shares that MCTs can vary greatly in behaviour, from slow-growing lumps to aggressive, fast-spreading cancers. Because mast cells contain chemical granules that release histamine and other substances, affected dogs may develop lumps that change in size or skin rashes. Some may experience vomiting, diarrhoea, stomach bleeding, or rarely, in severe cases, changes in blood pressure and collapse.
Diagnosis of MCTs typically begins with a fine-needle aspirate—a simple test where cells are collected from the lump for microscopic examination. Additional tests, such as blood tests, X-rays, ultrasound, or CT scans, may be recommended to assess whether the cancer has spread. Surgical removal is the main treatment and offers the best outcome for most dogs. When surgery is not possible or the tumour is aggressive, other options such as radiation therapy, chemotherapy, targeted therapy, electrochemotherapy, or Stelfonta®, a medicine injected to activate a dog’s immune system may be considered.
Prognosis (outlook) of MCTs treatments depend largely on tumour grade and whether it has spread. Dogs with completely removed, low-grade tumours often do very well, while those with high-grade or metastatic disease (spread) may face poor outlook. Early detection and treatment are critical. Any new or changing lump should be examined and sampled by a veterinarian as soon as possible. Because MCTs can look like harmless fatty lumps or cysts, prompt testing and treatment makes a big difference.
