Surgical Removal of Mast Cell Tumors in Dogs

Mast cell tumors in dogs can be either benign or malignant (cancerous). Surgical removal is a treatment option for mast cell tumors and is possible under some conditions. The mast cell tumors must be examined and graded; the stage of the tumor must also be established. The surgery can treat the tumor, so it might not reoccur, but the surgery cannot prevent the recurrence of these tumors.

Mast Cell Tumors

Mast cell tumors are excrescences on the surface of the skin or underneath it which are formed from mast cells. These cells are part of the immune system and protect the skin and the other organs from infections or toxins. The mast cells contain histamines, heparins and enzymes. When these cells are in excess, they can form a mast cell tumor.

Diagnosis of Mast Cell Tumors in Dogs

Mast cell tumors can occur on different parts of the body and may take different shapes. A biopsy will establish if the tumor is benign or malignant.

The tumors should be classified, to determine the best treatment option. Mast cell tumors may be graded as follows, depending on their severity:

  • Grade I tumors are benign and even if large, they can be removed and will not typically spread or grow larger; a large number of mast cell tumors are benign in dogs
  • Grade II tumors appear on the surface of the skin, but also grow under the skin; this type of tumor may be malignant and a clear prognosis cannot be given
  • Grade III mast cell tumors occur under the skin and are malignant, develop rapidly and may affect the entire body of the dog

The stages of mast cell tumors can also be established after the surgery is performed, according to how much they have spread out in the body. The stages are from 0 to IV, 0 being a tumor that hasn’t spread to any organs or lymph nodes. Stage IV mast cell tumors are in metastasis, meaning that they have already spread in the entire body.

Mast Cell Tumor Surgery

The surgery of mast cell tumors can be performed on grade I and II tumors. Typically, the removal surgery should cure grade I mast cell tumors; the cells will be removed and the tumor is less likely to grow back. The vet will remove some additional skin tissue surrounding the tumor (typically 1 inch), to ensure that the entire tumor has been removed.

In grade II mast cell tumors, surgery may be performed, but given the uncertainty whether the tumor is benign or malignant, the tumor may grow back after the surgery.

In grade III tumors, surgery may be performed, but the tumor is likely to grow back. Malignant tumors should also be treated with chemotherapy or radiation therapy.

Surgery may not be possible if the tumor is located in the internal organs such as the spleen or bone marrow, as the surgery can be very risky for the dog’s life.

Please note that each tumor should be treated differently, so consult a vet and find the best options for your pet.