Skin Tumors on Dogs and Cats
It happens to most pet owners. Your dog or cat comes to you for a scratch or belly rub, and you feel a lump. You think, how long has that been there? Could it be cancer?
Lumps and bumps are very common reasons for owners to bring their pets to the vet. There are several words used to describe them, such as growth, mass, or tumor. Although we associate the word “tumor” with cancer, calling a lump a tumor doesn’t necessarily mean that it is cancerous. A tumor is just an abnormal growth of cells. These masses are usually either on the surface of the skin or just underneath it. Some masses appear to look like warts or skin tags, while others are soft, squishy mounds of tissue. They can be freely movable under the skin, or they can be attached to deeper structures, such as muscle. They may cause the pet no trouble or discomfort, but some tumors can become ulcerated or infected and can affect your pet’s quality of life.
What are some of the causes of skin growths in dogs and cats? First, a lump may be caused by inflammation or infection. Inflamed skin can form a firm bump resulting from an insect bite, allergic reaction, or other minor trauma. There are even certain parasites that can burrow into the skin and cause inflamed lumps. A more serious injury such as a bite wound can cause an infected, fluid-filled mass called an abscess. Cat bites are notorious for causing abscesses due the bacteria in their mouths. An abscess usually appears as a fluctuant swelling, and it can become quite large before it eventually ruptures. Because dogs and cats have fur, smaller abscesses may not be noticed by owners until a discharge is present. Typically, lumps due to inflammation or infection are painful and uncomfortable for the pet.
Another cause for skin growths is abnormal proliferation of cells. Many of these types of tumors are benign, meaning they are not cancerous. Benign tumors typically include things like cysts, which may fill with fluid or glandular material from the skin, and fatty tumors, called lipomas, which are depositions of adipose tissue. Skin tags and wart-like growths are also usually benign, though not always. Even benign tumors can cause problems if they become irritated or infected, and they should be removed if they are bothering your pet.
Finally, some skin tumors are made up of cancerous cells. These tumors may be very aggressive locally, invading and destroying tissues where they occur. They can also be malignant, meaning they are capable of spreading elsewhere in the body. They may be solid or cystic, ulcerated or smooth, rapidly growing or present for a long time. Some skin cancers, such as mast cell tumors, can look like almost anything.
So, how do you decide if the lump on your dog or cat is worrisome or not? It is very important not to assume anything, and have the lump checked by your veterinarian. The doctor will perform a physical exam and will likely try to get a small sample of cells from the mass using a needle and syringe. Sometimes your veterinarian can examine these cells under a microscope and diagnose the growth, but often it is best to send the slides to a veterinary pathologist for evaluation. However, needle biopsy is not always diagnostic, and sometimes surgery is the only way to find out what you’re dealing with. This may involve taking a larger piece of the tumor to be sampled, or removing it entirely.
Check your pet regularly. Don’t forget to observe unusual places, such as inside the mouth or around the toe nails. Have your veterinarian check every new skin tumor that you notice. Don’t wait until the mass grows very large, because it becomes harder and harder to remove surgically. If a cancerous tumor can be completely removed when it is small, the chance for cure is higher, and you may not have to face decisions regarding more surgery, chemotherapy, or radiation for your pet. Your veterinarian is the best person to tell you if you should be concerned about a lump or bump.
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