Dog Skin Cancer - When Is a Tumor Malignant? Everything You Need To Know About Dog Skin Cancer

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Is it cancer? Is it benign? Finding a lump under your dog's skin can make pet parents very anxious, and rightfully so. Here are some important things you should know about dog skin cancer and the steps to take in getting a proper diagnosis.

Skin tumors are the most common tumors found in dogs. Some breeds, such as Boxers and Retrievers, are at a higher risk of having a skin tumor in their adult or senior years. Dog skin cancer is not always a given, though. Tumors may be benign (non-spreading or non-cancerous) or malignant (cancerous), but any lump should be looked at by a veterinarian.

Not all skin tumors may be caused by the sun, but sun exposure can increase the chances of developing tumors, especially if your dog has light colored fur. Areas that aren't covered by fur, like the nose and paw pads, are at greater risk of sun damage. You can take some steps to help prevent it, but the best defense against skin cancer is early detection, so talk to your vet immediately after finding any lumps.

Is it dog skin Cancer?

Certain skin problems can be mistaken for skin cancer. Some of them can be just as serious as cancer, so any questionable lump or growth should be examined and treated.

  • Benign Tumor: Sometimes tumors are not cancerous, but they may still need to be removed.
  • Fungal Infection: Ringworm and blastomycosis can cause skin lesions or significant irritation. Ringworm is highly contagious, and blastomycosis can cause significant lung damage so it is important to treat either infection as quickly as possible.
  • Allergic Reaction: Some allergic reactions, such as eosinophilic granuloma (although rare for dogs), can cause raised ulcers, especially on the mouth, face, feet and thighs.

If a tumor seems to be growing, or is an open wound that isn't healing, it’s more likely that the tumor is cancerous. Either way, make sure to have every tumor examined by a vet. They’ll be able to give you an exact diagnosis with a biopsy and other lab tests, and will likely recommend surgical removal and additional treatment, especially if the tumor is malignant.

Most Common Types of Skin Tumors in Dogs

Several skin tumor types are commonly found in dogs, and their prevalence has allowed vets to develop specialized treatments to best extend length and quality of life. If detected and removed early, some dogs can recover completely from some kinds of skin tumors. Other tumors may require more aggressive treatment, which can become very expensive.

  • Mast Cell Tumors: Mast cell tumors are the most common malignant tumors for dogs, and are usually solitary lumps found on the body or legs. Breeds which are at risk include Beagles, Boston Terriers, Boxers, Labrador Retrievers, Pugs, and Schnauzers. One strange side effect of the tumor is an increase in stomach acid and in likelihood for developing gastric ulcers. Since these tumors spread easily, vets will often start with surgical removal, but the use of radiation and chemotherapy has aslo been used to fight mast cell tumors.

  • Basal Cell Tumor: This form of tumor is one of the most common in animals, and among dogs, is often found in Cocker Spaniels and Poodles. These tumors grow from deep skin layers and can be seen as a single hairless lump on the head, neck, or shoulders. It is unlikely they will be malignant and there is low risk of spreading, so after freezing or surgical removal, many dogs recover completely.

  • Melanoma: Melanomas are often seen as a darkened area, sometimes looking like an overgrown or raised mole. They can be found on the mouth or mucous membranes, or in areas with hair -- even in the toes of black dogs. Melanomas grow very quickly, especially with sun exposure or licking, and can easily spread to the lungs and liver if not treated quickly. More than some other, slower growing tumors, melanomas are likely to require radiation or chemotherapy in addition to surgical removal.

  • Squamous Cell Carcinoma: This tumor is usually firm and raised, sometimes mistaken for a wart, and found on the abdomen or genitals. Basset Hounds, Beagles, Bull Terriers, Collies, Dalmatians, Keeshonds, Schnauzers, and other dogs with short coats are at risk. This tumor has been linked to sun exposure and possibly also the papilloma virus. While it is unlikely to spread to organs, it can still cause significant damage to surrounding tissue.

  • Hemanglosarcoma: This malignant tumor grows from blood cells, appearing as a raised, bruised lump (or multiple lumps) on the hind legs or abdomen. The lumps may change in size or color but are often firm and malleable. Boxers, English Setters, German Shepherds, Golden Retrievers, Pit Bulls, Whippets, and older dogs are more likely to have hemanglosarcoma. These tumors are more likely to metastasize (spread to new areas or organs), and sun exposure for light-colored dogs may have a predisposition to getting hemanglosarcoma. This tumor will require surgical removal and probably ongoing radiation therapy because it is so aggressive. Unfortunately, it usually shortens a dog's lifespan.
More on Canine Diseases

Heart Disease in Dogs and Cats
How Dogs and Cats Get Heartworm Disease
Dog Cushing's Disease

This information is for informational purposes only and is not meant as a substitute for the professional advice of, or diagnosis or treatment by, your veterinarian with respect to your pet. It has, however, been verified by a licensed veterinarian for accuracy.

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