Like humans, dogs and cats can also develop skin cancer.
Most notable are cancers of the skin cells (squamous cell carcinoma) or cancers of the pigment-producing cells (melanoma). Other tumours, such as malignant blood vessel tumours (hemangiosarcoma) and benign blood vessel tumours (hemangiomas) have also been described and associated with sun exposure.
Risk Factors for Skin Cancer in Dogs and Cats
Excessive UV light and sun exposure has been a documented risk factor in humans, and is proposed to contribute to similar risk in dogs and cats. However, it should be noted that those most at risk are thin-haired and light-colored breeds. These animals typically have skin exposed, which may explain the higher incidence of skin cancer.
Breeds including Bloodhounds, Basset Hounds and Standard Poodles appear to have a predisposition to developing skin squamous cell carcinoma, attesting to a possible genetic component to the development of this disease.
Skin Cancer Diagnosis and Treatment
The first thing you may notice is a mass located on the skin. It could be small to start, and may be darkly pigmented (melanoma) or the same color as the skin. Even if the mass is not pigmented, a melanoma is still possible.
In cats, squamous cell carcinomas associated with sun exposure are most commonly noted on the nose or bridge of the nose. These lesions are frequently crusted and eroded (like a cut on the skin). Dogs can also develop squamous cell carcinomas of the skin or nose itself.
The majority of skin melanomas in dogs tend to act in a benign fashion, with low rates of spread to other organs. With complete removal by surgery, most dogs do not require further therapy. However, if testing reveals that the cancer has not been removed completely or has characteristics that make it appear aggressive, further therapies may be warranted.
Similar to melanomas, surgery is the mainstay of therapy for squamous cell carcinomas. Again, this is a relatively uncommon diagnosis in dogs, and is more often observed in cats. When possible, surgery should be pursued to remove as much of the tumor as possible. If surgery is not an option or is unable to remove all cancerous cells, radiation therapy is sometimes pursued.
Preventing Skin Cancer in Dogs and Cats
The role of UV light exposure is still controversial in cats and dogs, but is considered a risk factor. Therefore, excessive exposure to sun should be avoided. Shirts and other coverings can be used in pets with very thin hair coats (or lack of hair) to protect their skin from excessive sun exposure.
If your pet has light hair, sunscreen may be applied to areas over the nose and nasal bridge. Sunscreen should be pet-safe; components such as zinc oxide and para-aminobenzoic acid (PABA) are toxic to pets. Consult your veterinarian about choosing an appropriate product.
Regardless of preventive measures, skin cancer may develop and pet parents must be vigilant. The earlier a mass or cancer is diagnosed, the better. If you notice a lump or bump that is concerning you, consult with a veterinarian so it can be investigated.