Skin Cancer on Dogs

by Sarah

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Skin cancer on dog's lip

Can Dogs Get Skin Cancer?

They absolutely can. The skin cancer that is most aggressive on a dog is the same type that is aggressive on humans: malignant melanomas. Don’t confuse these with benign tumors called melanocytomas, which are benign tumors. Both of these, however, come from the cells in the skin that produce dark pigment. If you are able to tan easily, it is said that you have more melanin in your skin, than say a friend who doesn’t. Melanin also creates dark hair.

What many people don’t realize is that veterinarians don’t think that skin cancer on dogs is caused by exposure to sunlight. It is believed that genetics play a huge role in this and some breeds are more prone to malignant melanoma, such as the Chow.

What does skin cancer look like on a dog?

Just like other cells in the body, they can become cancerous and the tumors are not just found on the skin. They can happen inside the mouth, in the eye, even on toes. The tumors themselves are typically dark and solid to the touch; they are visible to the eye.

Skin Cancer in Dogs Symptoms

Obviously the first sign is a dark, fleshy mass on the dog’s body. As the cancer spreads, it spreads internally and can reach areas like the lungs. Once it is in the lungs, a dog may experience coughing, weight loss, decreased appetite, and blood in the mucous that is coughed up.

As I mentioned above, there are some benign tumors caused by melanin. These are usually the tumors found on parts of the skin with hair. The real trouble comes if the tumor is in the mouth, the edge of the lip, or the toe. These are areas where haired skin meets non-haired skin and the cancer can quickly spread internally to the lymph nodes, lung, liver, and adrenal glands.

Treatment for Skin Cancer on Dogs

Surgery is the primary way to remove a malignant melanoma or a melanocytoma. Prognosis with surgery is best if the tumor is only on skin with hair. If the malignant melanoma is in the mouth, surgery will be attempted. Chemotherapy does not typically work well with melanomas in the mouth. About 1 out of 5 dogs will respond to the chemo, but these types of tumors spread so quickly, it’s too difficult to treat all of the areas where the cancer has metastasized. Radiation has shown to reduce the size of the tumor in some dogs, but it will most likely grow or reappear later.

If the melanoma is on the toe, many veterinarians will recommend amputating the affected toe. Tumors on the toe also spread (metastasize) very quickly so that by the time surgery takes place, the cancer has probably already spread. The cancer cells that have migrated may be too small to see on a scan at first but will eventually grow other tumors in other parts of the body.

There is currently an experimental vaccine for dogs with malignant melanoma to boost a dog’s immune system and prolong their life after treatment. This vaccine can only be requested from your vet.
If your dog is experiencing any medical problems, please take him or her to your veterinarian immediately.

Osteosarcoma in Dogs

by Sarah

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Osteosarcoma in dogs occurs most frequently in the legs

The word “osteosarcoma” comes from “osteo” for bone (like in the word osteoporosis) and “sarcoma” which means malignant tumor. In short, it is bone cancer. The bone where this cancer is most likely to appear is in the leg and most oftentimes it is just found in one leg, The tumor grows within the bone. It is rare for osteosarcoma to be in another bone, but it can happen.

Osteosarcoma Symptoms in Dogs

Pain is the number one sign with this cancer, as the tumor will grow and cause swelling. This often causes the dog to limp. Sometimes you are able to see the protrusion of the tumor if it is on the lower leg where there is less muscle.
As the tumor continues to grow as the cancer advances, it can cause the bone to break just from normal activity like walking, which puts weight on the weakened bone.

Other symptoms may include problems in the lungs or other areas of the body, as well as decreased appetite resulting in weight loss.

Osteosarcoma Causes in Dogs

There are certain brreds that seem to develop osteosarcoma more often than others: Greyhounds, Rottweilers, Irish Wolfhounds, and other big breed dogs that are over 75 lbs; dogs of this size are two times more likely to develop this cancer than their smaller breed counterparts.
Rare risk factors include previous bone fractures where a bone plate was used, if a bullet was lodged in a dog’s bone, and previous infections. Again, these are rare but the fact that these things all cause inflammation cannot be ignored. Inflammation is sometimes seen has spurring cancer on.

Osteosarcoma in Dogs Treatment & Prognosis

Unfortunately, osteosarcoma often metastasizes. This means that the cancer spreads to other areas. These small cancer cells that spread are called micrometastastis and they cannot be seen by an X-Ray or other body scan. The cells may be lying dormant until it grows enough to cause another tumor. This makes the cancer tough to treat. It is said that potentially 90% of dogs diagnosed with osteosarcoma already have micrometastasis.
Amputation if the osteosarcoma is in the leg is the typical surgical choice. If just surgery is performed, the prognosis can be 4-5 months. About 11% of dogs will leave for a year and around 2% will make it for two years. Combining the surgery with chemotherapy can increase the survival time to 6-13 months, approximately longer. The veterinarian will decide which course of chemotherapy drugs to administer. Pain meds will also be given to keep the discomfort at bay. Radiation can also help with pain management but not as an approach to get rid of the osteosarcoma. It is important to consider the pain medication and radiation as supplying the dog with a better quality of life.
There are always new technologies underway for surgery, chemotherapy and radiation. As always, bring your dog to the vet immediately whenever there is a medical issue.

Mast Cell Tumors in Dogs

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