Benign and Malignant Skin Tumors in Dogs

Skin tumors in dogs may be of several types: benign tumors or malignant tumors that include melanomas, epithelial tumors or round cell tumors. The distinction between a benign and a malignant tumor may be made by running a few tests on the tumor. Skin cancer is among the most common types of canine cancer.

Benign Tumors

The benign tumors may occur as lumps or lesions on the surface of the skin; typically, the benign tumors will have a regular shape and will develop at a slow rate. These tumors may keep their same size, as opposed to malignant tumors that will grow and spread at an alarming rate.

A benign tumor will not affect the dog’s health and should be removed only if the tumor causes discomfort or hinders the dog form breathing or moving. 

Malignant Tumors

Malignant tumors may form on the surface of the skin and may be felt as swellings or visible as lesions or sores that heal very slowly. The malignant tumors may be of different types:

  • Epithelial tumors
  • Mesenchymal tumors
  • Round cell tumors, which can be of several types including lymphosarcoma, mast cell tumors, histiocytomas, plasma cell tumors
  • Melanomas, which are pigmented tumors

If the skin tumor is malignant, the dog will also display some symptoms such as skin itchiness, redness, lack of appetite, lethargy and flaky skin. The dog may often scratch or chew the affected skin area.

The skin cancer is more frequent in middle aged or senior dogs (6 to 14 years old) and some dog breeds are more prone to developing malignant skin tumors.

The cause of skin tumors is not known, however, the occurrence of skin cancer has been associated with excessive sun exposure.

Tests for Skin Tumors

The typical test that is performed on skin tumors is the biopsy; this test will establish whether the tumor is benign or malignant.

A small portion of the tumor will be removed and tested under the microscope to determine the type of cells that form the tumor.

If the tumor is small the vet may perform an excision biopsy, which involves the removal of the entire tumor. However, if the tumor is malignant, there are high chances that the tumor will grow back and expand.

If the skin tumor is malignant, the vet should also establish the stage of the cancer, so that a suitable treatment can be established.

Treatment Options for Skin Tumors

The treatment for skin tumors will depend on the type of the tumor that affects the dog. Typically, benign tumors should be left alone; there is no need to remove these, as they are less likely to expand and won’t cause any health issues.

Malignant tumors may be removed through surgery and the dog also needs to get chemotherapy that will stop the cancerous cells from spreading. In some cases, the tumor may be too large and surgery may not be possible; also if the cancer has metastasized, surgery will not help.

Radiation therapy may also be applied, but this will not treat the cancer; it will only relieve the pain.