Identifying Mast Cell Tumors in Dogs: 7 Visible Signs

Mast cell tumors are a common skin cancer in dogs of all breeds and ages. If caught early, some mast tumors can be removed easily. Early diagnosis is essential, however, so look out for these signs on your dog.

Visible Signs of Mast Cell Tumors

  • Lump on or under the skin, particularly on the trunk, genitals and limbs, but possibly anywhere on the body as single or multiple bumps, though they are usually solitary
  • Swelling and itching at lump site
  • Lump gets swollen or grows in size
  • Vomiting
  • Loss of appetite
  • Diarrhea
  • Bloody stool

The main sign of mast cell tumors are bumps on the skin which can be pink or red, and hairless. Mast cell tumors can also spread to the gastrointestinal tract, bone marrow, spleen, lymph nodes and liver. Bring your dog to the vet once tumors on the skin can be seen. The vet will take a biopsy of the lump and look for mast cells. If it is still in the early stages the tumor may be removed easily with surgery and is unlikely to recur. Chemotherapy and radiation treatment are also options for higher grade tumors.