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Melanoma in Dogs

melanoma in dogs


Cancer. No other word instills fear in our hearts like this one. It makes no difference if it applies to us personally, a family member or a beloved friend – a diagnosis of the “Big C” is life-altering.

Now imagine your veterinarian telling you the swollen spot on your dog’s lip is cancer. The same anxiety steals your breath. The same fear seizes your chest. The same uncertainty and panic churns your stomach. A cancer diagnosis in your fur-baby is just as devastating as it would be in any other beloved family member.

What Is Melanoma?

The term “melanoma” is a broad classification for cancer in the cells that contain melanin, like the cells that create freckles and moles. These types of harmless, or benign, conditions are “benign melanomas,” or melanocytomas.

Malignant melanomas that present serious health issues which are potentially life-threatening if not treated. Malignant melanomas are the cancerous form of skin conditions that mimic freckles, moles and other lumps and bumps.

Among the human population of the United States, cancer is the second leading cause of death annually. Three million people each year find out they have some form of skin cancer. Luckily, it is not fatal in 85 percent of cases.

Cancer is the leading non-accident-related cause of death among dogs in the United States. Among fur-babies, about six million each year face a diagnosis of some type of melanoma cancer. About one-third of all cancers in dogs occur where the cells contain a substance called melanin. This is what gives the dog’s skin, eyes and fur its color.

Specifically, melanoma is cancer in the skin cells that have some color in them: black noses, lips and gums, brown around the eyes, a belly covered in freckles, the dark pads of the feet, the dark brown iris of the eye.

Like skin cancer in humans, melanoma in dogs is highly treatable. Early detection and treatment is as crucial in successfully treating furry family members as it is in our human relatives and friends.

Types of Melanoma in Dogs

There are four main types of melanomas found in dogs. The location determines how they’re categorized.

  • Oral melanoma. This type of cancer can appear anywhere around or in the dog’s mouth.
  • Cutaneous melanoma. These are the cancerous spots appearing on the dog’s skin.
  • Ocular melanoma. This form occurs in the eyelids or in the eyeball itself.
  • Subungual melanoma. This type of cancer appears in and around the nail beds and foot pads.

Each type of melanoma has its own characteristics and behaves in its own way.

Oral Melanoma

If you look at averages, about 80 percent of melanomas in dogs occur in the oral cavity. This means the cancer is in the dog’s lips, gums, tongue, or roof or floor of the mouth (the hard or soft palate.)

These cancers are usually single lesions such as hard or soft knots under the skin or nodules on top of the skin. But they can be deceptive. While it may look like a solitary knot on the dog’s gum, underneath it can be extending into the muscles and bones.

These tumors will many times appear dark or black in color. But they can be pink or a mixing of colors, such as pink, white and black. Some may not look like a mass, bump or knot at all. Some may appear as a flat, flakey area.

Small breed dogs are at a higher risk for oral cancers than larger dogs. Although any breed of dog can be stricken with melanoma, it is most likely to affect miniature poodles, chows, cocker spaniels and golden retrievers.

This type of melanoma usually shows up in dogs that are around ten years or older.

Cutaneous Melanoma

This type of skin cancer in dogs is also called dermal melanomas. These areas usually show up as a dark spot on the dog’s skin. It may or may not be a raised mass, like a swollen spot. There may be more than one suspicious spot or it could be a single area that takes on a different color.

Cutaneous melanomas that occur in skin that’s covered in hair are non-cancerous in 85-90 percent of cases. Surgical removal of the suspicious area with a biopsy of the removed tissue is the best way to determine if your dog will need further treatment afterward.

Ocular Melanoma

These are cancerous lesions found in and around the dog’s eyes. They most often occur around the eyelid and on the inner surface of the upper or lower lids. Some may even appear on the surface of or inside the eyeball itself.

Most lesions in and around the dog’s eyes are cancerous. They are frequently the result of a cancer elsewhere in the body that spread to the eye. Any tumor in or around the eyes, whether it’s cancerous or not, can cause vision problem for the dog and should receive treatment as soon as possible.

Subungual Melanoma

Subungual melanomas occur in the dog’s nail bed. These are the second most common location for cancer in canines, occurring in 15-20 percent of dogs. These are usually single lesions rather than multiple cancerous spots.

Unfortunately, this type of melanoma is prone to spreading through the lymph nodes. It is, therefore, imperative to check lymph nodes in the surrounding tissue be checked when subungual melanoma occurs.

Detection of Melanomas

Whether the melanoma is benign or malignant, the chances for a complete cure improve dramatically with early detection.

Benign melanomas are usually found on the surface of the dog’s skin.

  • appear as firm, round, raised masses
  • usually are darkly colored
  • size will vary, from a quarter of an inch to two inches in diameter
  • found most often on the dog’s paws, back or head
  • Can appear black, brown, gray or red in color

Malignant melanomas occur most often in and around the dog’s mouth.

  • can occur or spread to just about anywhere on the dog’s body
  • in and around the mouth, the pads of the feet and the toenail beds are the most common locations
  • usually have an abnormally dark color, although this is not always the case

The key to early detection is to check your pet frequently. Rub your hands over his skin, including between his toes.Take a look at the inside of his lip. He won’t mind the attention one bit!

Common Symptoms of Melanoma

The earliest symptoms are the appearance of lumps, knots, discolored spots and areas that are sensitive to touch. There are some generalized symptoms associated with skin cancers and melanomas that have spread to other parts of the body.

  • diminished appetite
  • vomiting
  • diarrhea
  • coughing
  • lack of energy and enthusiasm
  • wounds that won’t heal

But there are also more specific symptoms that point to a potential melanoma.

Oral Melanoma

Dogs who have melanomas in or around the mouth will generally show one or more of the following symptoms:

  • Loss of appetite due to pain and difficulty eating.
  • Bad breath.
  • Abnormal or excessive drooling.
  • Swelling around the face.
  • Chewing on one side of the mouth.
  • May bleed from the mouth.

Cutaneous Melanoma

Most tumors on the skin are benign but they should be properly evaluated, nonetheless. Benign skin melanomas are usually single growths.

  • small, firm and easily movable
  • usually found on the face, near the eyelids, on the trunk and the extremities.

Cancerous tumors are fast-growing, ulcerated and change colors.

  • are usually found on the head, belly and scrotum
  • commonly spread to the lungs and lymph nodes
  • may spread to the heart, brain and spleen.

Ocular Melanoma

Cancers in the eye usually show up as an obvious mass on the surface of the eye or inside it.

  • there may be blood on the front surface of the eye
  • early stage symptoms may look like a freckle on the colored part of the eye (the iris.)
  • may look like a dark, smooth nodule on the iris
  • can occur in one eye alone or in both eyes simultaneously
  • ocular melanomas are usually painful so the dog may shake his/her head frequently or rub a paw across the eyes

Subungual Melanoma

Dogs who suffer from subungual melanomas are often misdiagnosed because the cancerous lesions tend to become infected. Seek a veterinarian’s opinion on any sore or infected area on the foot pads or nail beds.

The first sign of a potential subungual melanoma is lameness. Your dog will limp because the foot or feet hurt.

Diagnosing Melanomas

Early detection is essential. Any mass on or under the skin that’s been there for more than a month and is larger than the size of a pea warrants a veterinarian check. This checking may include either aspiration of the mass or a biopsy.

  • Aspiration means inserting a needle into the tumor and removing some cells. This procedure usually doesn’t involve sedation.
  • Biopsy is a surgical procedure in which the veterinarian removes all or part of the tumor. The removed tissue is then examined by a veterinary clinical pathologist to obtain a definite diagnosis.

The veterinarian may also do a battery of blood tests to determine how the organs in the rest of the dog’s body are functioning. He/she may take chest x-rays to look for the spread of cancer into the lungs or heart.

A sonogram of the dog’s belly can check for the spread of cancer to internal organs like the liver and spleen.

The veterinarian may also do an aspiration of the lymph nodes around the area of the suspected cancer to check for spread of cancer cells.

Treatment for Melanomas

Once it’s determined your fur-baby has cancer, the best first treatment is surgical removal if possible. Surgical removal of the tumor gives the dogs the lowest chance of the tumor re-occurring during their lifetime.

In all cases, if the disease is in the surrounding lymph nodes, these need to come out at the time of surgery.

Oral Melanoma Treatment

Cancers in the gums or soft tissues inside the mouth, or cancer involving the jaw bone usually require surgery to completely remove the upper or lower jaw. Dogs who undergo this procedure do exceptionally well following surgery. There is generally a minimal to no impact on their ability to function and have a normal quality of life.

There are some locations in the mouth that make surgical removal of tumors difficult. Frequently the veterinarian can remove a large portion of the tumor but your dog may need additional therapy to prevent the tumor from regrowing.

Cutaneous Melanoma Treatment

Cutaneous cancers are frequently removed with a mild sedative and local anesthetic.

If the melanoma has spread into the tissues underlying the skin, surgical removal will be more involved. This usually means general anesthesia and possibly an overnight stay at the vet’s office.

Ocular Melanoma Treatment

This form of melanoma can be difficult to diagnosis. For this reason, supportive treatment is usually started when the veterinarian suspects an ocular melanoma. Initial treatments may include anti-inflammatory drugs, supplements, regular eye cleaning procedures and frequent monitoring by the veterinarian.

In the later stages of the disease, surgical treatment may be an option. Unfortunately, many cases of ocular melanoma are secondary tumors. This means there’s another tumor somewhere in the dog’s body that’s spread to the eye.

Subungual Melanoma

The first recommendation for most cancers in the footpads or nail beds is amputation. It the tumor is small, removal may only involve the toe, or two if the tumor is between the toes. With large tumors or those with chronic infection associated with it, the best treatment may be amputation of the entire foot.

Chemotherapy and Radiation Treatments

Radiation therapy can be effective in cases where the cancer’s location or size makes surgical removal impossible. If surgery can remove only part of the tumor, radiation therapy may help prevent regrowth.

Chemotherapy is not a very effective method of treatment for cancer in dogs. It usually extends life expectancy by a few months, at best.

The current treatment of choice for preventing the spread of a cancer that’s been surgically removed in the melanoma vaccine. Your dog will receive a treatment every other week for four treatments, then a booster every six months after that.

Prevention of Melanoma

Some types of melanomas are preventable, while some are not. Most cancers in dogs result from a genetic predisposition.

The major risk factor that is completely controllable is exposure to sunlight. Light-skinned, short-haired dog breed should curtail their exposure to direct sunlight. Bringing them inside or providing shade during the peak daylight hours may lower the risk of skin cancer in these pets.

The best prevention is early detection. Check your dog frequently for dark masses or nodules. Pay special attention to your fur-baby’s belly and armpits. He won’t mind you rubbing over these areas to feel for bumps and lumps.

Look lovingly into your dog’s eyes to check for spots in the iris or the whites of his eye. Check his eyelids for bumps.

Shake hands with your pet. While you’ve got his paw in hand, check the pads, between the toes and around the nail beds for swelling, soreness, bumps, lumps or any type of open, infected-looking sore. Don’t limit your inspection to the paw he offers for shaking – check each of them.

Don’t forget the tail! Run your hand over the length of his wagger to make certain there are no strange bumps, lumps or masses there.

You know your fur-baby better than anyone. If something doesn’t seem right, it probably isn’t. If your dog is constantly licking at the same spot on his body, be suspicious. Schedule a check up with your veterinarian.

Often when dogs don’t feel right, they don’t act right. If your dog starts acting strangely or suddenly loses interest in playing, cuddling or eating his favorite treat, it’s time for a trip to the vet’s office.

Beating the “Big C”

Cancer is a frightening diagnosis for anyone, human or fur-baby. It can be a challenging disease to beat, but it is beatable.

With early detection, proper treatment administered in a timely fashion, and the tender loving care of his human family, a dog’s chances of surviving to live a happy, healthy life are remarkable.

Beating the “Big C” is not as tough as it used to be.

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