Canine Toe Cancer

Malignant melanoma can develop in a dog's toe.

Cancer of the toe is not unusual in dogs. The most common type is squamous cell carcinoma, which can also affect skin and other tissues. Malignant melanoma, or cancer of pigment cells, can occur on the toes, skin, mouth and eyes. Mast cell cancer arises in mast cells, part of the immune system that helps fight infections. Mast cells are found in the skin, intestines, other internal organs and respiratory tract.

Breeds at Risk

Large dogs and black dogs are more susceptible to squamous cell cancer. Scottish terriers, Boston terriers, Airedale terriers, cocker spaniels, boxers, Springer spaniels, Irish setters, Irish terriers, chow chows, Chihuahuas and Doberman pinschers are prone to malignant melanoma.

Mast cell cancer is more common in boxers, Boston terriers, pugs, English bulldogs and other breeds with a short, wide head as well as golden retrievers. Older dogs are more vulnerable to all cancers.

Symptoms of Toe Cancer

Squamous cell toe cancer may appear and a reddish lump or blister that does not go away. Symptoms may include a swollen toe or foot, limping, bleeding sore and a broken toenail.

Malignant melanoma usually occurs as a single brown-to-black tumor that may grow quickly or slowly. The tumor might cause the dog to limp. Mast cell cancer typically occurs as lumps on or underneath the skin. Tumors can be single or multiple and can be smooth or rough or can break open.

Diagnosis

Diagnosis typically begins with chest and abdominal X-rays, an X-ray of the affected foot and a complete blood count and biochemistry profile. Your veterinarian may also order a CT scan, sample lymph fluid and send a biopsy of the tumor to a laboratory for analysis.

Treatment for Squamous Cell Cancer

The cancerous toe should be removed surgically. Dogs treated this way recover uneventfully and have no problem walking. If the cancer has spread, your dog will need chemotherapy along with pain medication. If all of the tumor cannot be removed, radiation therapy can be used along with or after chemotherapy. Dogs treated for an isolated squamous cell tumor usually don't have a recurrence. Dogs with cancer that has spread typically survive about a year with treatment.

Treatment for Malignant Melanoma

The affected toe will be surgically removed, and the dog should receive chemotherapy or radiation, particularly if the tumor could not be completely removed. The Department of Agriculture has approved a new vaccine to treat canine melanoma, which is available if your dog is enrolled in a clinical trial. Consult a board-certified veterinary oncologist in your area for additional information.

Treatment for Mast Cell Cancer

Mast cell tumors are treated with surgical removal of the affected toe and with radiation. If the cancer has spread, your veterinarian may recommend chemotherapy or a medication called toceranib phosphate, which attacks the cancer cells and cuts off the blood supply to the tumor.

References

• PetMD: Tumor on the Toe in Dogs
• Petside: Melanoma in Canines
• PetEducation: Canine Mast Cell Tumors