One day, you might be petting your beloved pup or brushing its hair when you notice a lump or bump on the skin that wasn’t there before. Finding bumps can alarming. They can be a sign of a health issue and, if they are under the skin, aren’t always easy to identify.

If you’ve recently discovered a strange lump on your dog, it could be one of a few different things. Here’s what you should know about lumps and bumps on dogs and what you should do if you find one.

Potential Causes of Lumps and Bumps

Before you automatically assume your dog’s bump is cancerous, remember that there are many causes of skin lumps and bumps in pets. Here are some of the most common.

• Hives or allergic reactions: Numerous small bumps on the skin may be caused by bug bites, an allergic reaction manifesting on the skin or contact with an irritant. These bumps generally appear red and may be itchy to your dog. They tend to go away on their own, but may require a topical ointment or antihistamine to relieve the swelling and itchiness.
• Injection-site reactions: If your pup was recently vaccinated, it may develop a small lump under the skin where the needle was inserted. These types of bumps are relatively normal and should disappear in around two weeks (or sooner). You’ll want to keep an eye on bumps near injection sites, though, because some can develop into cancerous tumors (although this condition is rare).
• Cysts: Sometimes, dogs can develop what are called sebaceous cysts, or clogged oil glands in the skin. These cysts can develop because of a buildup of sweat or dead skin cells and cause a moderate-sized bump underneath the skin. Usually, these are nothing to worry about. Sebaceous cysts tend to rupture on their own and heal, similar to a pimple in humans. However, some will not rupture and heal independently. If the cyst is causing your dog pain or discomfort due to its location and is not going away, or it appears to be infected, it may need to be removed by a professional.
• Benign tumors: A lump or bump beneath the skin may also be a tumor. Although the word “tumor” can be scary, not all lumps are harmful. Some tumors, like lipomas, are actually benign fatty growths that only reach a certain size and will not invade surrounding tissues. These types of growths may need to be removed depending on their location but are generally not harmful.
• Malignant tumors: Other tumors may be malignant, meaning they can spread rapidly, invading surrounding tissues and creating serious health problems. Malignant growths on our pups are generally what we think of when we think of dog cancer.

Next Steps After Finding Lumps and Bumps

Once you identify a lump on your dog, you’ll want to investigate further to see what kind of lump it is, identify the size, shape and color, and more. Gather as much information about the lump as you can right away.

Monitor it

Monitor the lump for a day or two at home, looking for signs of change, discomfort and severity. Some major things to look for in lumps and bumps include rapid changes in size or shape, swelling, redness, pus, blood or significant pain from your dog.

Also, keep an eye on your dog’s behavior and any symptoms of health issues it might be displaying. Hiding, lethargy and reduced appetite could be causes for concern.

Seek veterinary care

If you’re concerned about a lump on your dog’s skin that has not gone away on its own or continues to grow, you should take your dog in to a veterinarian. There, the vet will conduct numerous tests to identify what the lump is. They may determine that the lump is something minor like a cyst. Or, they may suspect cancer and need to conduct biopsies to examine the tissue cells to determine the specific root cause.

The type of lump your vet identifies will determine what course of treatment will need to be followed. The lump may be able to be removed by your vet right away, or your dog may need to undergo surgery or more intense treatment to stop cancerous growth.

In general, it’s a good idea to make a habit of checking your dog’s body over for lumps and bumps. Routine grooming is a great time for this. As you’re brushing your pup’s coat, use your fingers to check for any abnormalities on your dog’s skin or monitor any changes in existing bumps. With careful attention to your dog’s skin, you’ll be prepared to find and treat lumps and bumps of all kinds as soon as possible.