Lumps and Bumps On Dogs

As our dogs get older, it is common for lumps and bumps to form on or under the skin. Are they concerning? Is it cancer? Well, it depends on what type of cells the growth is made of. It is impossible to know with 100% certainty the nature of a growth or tumor without first testing it; this is important enough to repeat: all growths should be tested to determine if they are cancerous or benign.

In the following article, I will describe some of the more common growths encountered by veterinarians. With this knowledge, you will have the information needed to understand what that growth is once it has been tested, and a diagnosis achieved.

Common Benign Growths

There are many types of benign growths in dogs: Lipomas, Papillomas, and Keratinizing Acanthomas, to name a few. In more common terms, as dogs get older, they become prone to developing benign tumors of fatty tissue (lipomas), warts on the skin (Papillomas), or cystic lesions with a white to gray, gritty substance inside (Keratinizing Acanthomas).

These lesions are benign, which means they are not cancerous and do not spread to vital organs. However, many of these growths are unsightly to owners or can burst open on their own and become infected. They can pop up just about anywhere on or under the skin. Some tend to appear and gradually enlarge over long periods.

Most times, just keeping a careful eye may be all that is needed, as they are not painful or tend to cause ongoing problems. In cases where these lesions keep opening up, become infected, or restrict movement, surgical removal can be considered.

Also, there are other kinds of benign growths that are worth mentioning. These tend to occur in younger dogs and seem to appear suddenly. Viral Papillomas and Histiocytomas are both benign growths that occur in younger dogs.

Viral Papillomas are contagious growths that appear in the mouth or on the belly, often in dogs that frequent the dog park or other high trafficked areas.

Histiocytomas appear as red, raised, round growths on the skin. Fortunately, both are benign, and both often spontaneously disappear without treatment after a few months.

Cancerous Growths

Unfortunately, dogs can also get cancerous growths, some of which can be very dangerous to your dog. While there are too many types of cancerous skin growths to go over in one article, some of the more common cancerous growths I see are Mast Cell Tumors, Squamous Cell Carcinoma, Malignant Melanomas, and Subcutaneous Lymphoma.

Mast Cells are sometimes referred to as “The Great Imitators” because they can look like other common benign growths. However, their typical appearance is a round, raised, circular growth that appears on your dog. Mast Cells vary in their aggressiveness and can be graded on a scale based on their clinical features. Because these tumors can be great deceivers, it cannot be overstated how important it is that every growth be tested and subsequently diagnosed as either cancerous or benign.

At the Vet

When you take your pet to the Veterinarian to get their growths checked out, the veterinarian will ask about your pet’s history. You will be asked about when the growth appeared, whether it has changed over time, and whether it seems to be bothering your pet. Your veterinarian may then take a sample, which can be analyzed under a microscope. There are two ways to do this.

Firstly, a fine needle aspirate is a quick, relatively painless test where cells can be taken from the growth and applied to a microscope slide. Alternatively, biopsy is a slightly more invasive test where either a small piece of tissue or the entire growth is surgically removed and then tested. Biopsies can give more information about the architecture of a growth and may yield more information but are slightly more intrusive. Both tests are very safe.

Based on the appearance of the growth, your Veterinarian will decide which test is more appropriate. An aspirate may be taken in some cases, yielding results that recommend further investigation and that surgical removal and a biopsy are indicated. On the other hand, your Veterinarian may elect to remove the growth and submit it directly for an evaluation. When a growth is more concerning on appearance, painful, ulcerated, or in any way affecting the quality of your pet’s life, this may be recommended.

If you have noticed a new growth on your dog, or even an old one that you never got checked out, I recommend scheduling an appointment with our Veterinary Hospital. After a history, physical examination, and proper testing, a diagnosis can be made; this can help identify the nature of the growth and help give you the peace of mind of knowing the nature of that growth.

Jeffrey Stupine V.M.D.

Medical Director

World of Animals Veterinary Hospitals