Lumps And Bumps On Dogs

As our dogs get older, it is usual 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 testing it. This is important enough to repeat again…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 just to name a few.  In more common terms, as dogs get older they are 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 meaning 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 then become infected. They can pop up just about anywhere on or under the skin. Some tend to appear and get larger slowly over long periods of time. In many cases, 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.

There are also other 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 tend to occur in younger dogs. Viral Papillomas are contagious growths that tend to appear in the mouth or on the belly, often in dogs that frequent the dog park or other high trafficked areas. Histiocytomas tend to 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 is again important to recognize that every growth should be tested to arrive at a diagnosis.

At the Vet

When you take your pet to the Veterinarian to get their growths checked out, history will be taken. You will likely be asked about when the growth appeared, if it has changed over time, and if it seems to be bothering your pet. Your veterinarian may then take a sample that can be analyzed under a microscope. There are two ways to do this. A fine needle aspirate is a quick, relatively painless test where cells can be taken from the growth and applied to a microscope slide.  

A 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. In some cases, an aspirate may be taken which yields results that recommend further investigation and that surgical removal and a biopsy are indicated or your veterinarian may elect to simply remove the growth and submit directly for 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 a member of our Veterinary Hospital.  After a history, physical examination, and proper testing, a diagnosis can be made. This can help not only identify the nature of the growth, but help give peace of mind by knowing what the nature of that growth really is.

Jeffrey Stupine VMD

Medical Director

World of Animals Veterinary Hospitals