Hard Tumors in Dogs

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Just because you dog has a lump doesn't mean that it is a bad thing.
Image Credit: Sally Anscombe/Moment/GettyImages

You're petting your dog after she fetched and returned with the tennis ball for the hundredth time (and she's not worn out yet!) and you unexpectedly feel a hard lump. Your first reaction may be to quickly stop the game and give her whole body the once over. While it is scary to feel a hard lump on your dog, no matter where it is on her body, don't panic!


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A hard growth on a dog may be the result of something that is perfectly normal. Get any lump checked out by a vet though, as some bumps may be tumors, and early tumor detection makes a big difference in your pet's prognosis.

Cancer in dogs

Cancer is the most common cause of death in dogs, says the Journal of Veterinary Medicine. The Journal reported on a study looking at 82 dog breeds, and cancer was the leading cause of death for 71 of the breeds studied.


Sometimes, the signs of cancer are not apparent at first. You may notice that your dog has a small bump somewhere, but at the same time you may feel that he is eating, drinking, and playing normally so there is nothing to worry about. As it turns out, abnormal growths, lumps, or tumors are among the most common signs of cancer in your pet, so don't ignore them if you see them. The National Cancer Institute's Center for Cancer Research says that each year about 6 million of the 65 million pet dogs in the United States will be diagnosed with cancer.


Hard lump on dog

Pet Life Today explains that dogs develop hard lumps for a variety of reasons. Blocked hair follicles, bug bites, a blood clot that appears as a lump on the skin (called a hematoma), and even cysts can all turn into lumps that are not the same as a cancerous lump. A cancerous lump will behave differently than a non-cancerous lump in many cases.


Cancerous lumps will often grow quickly. It may change its color or appearance in other ways, and it will likely also do this quickly. A cancerous lump may have a different color of skin than the skin around it. It also may feel like you can't tell where the edges of the lump end.


Hard knot on dog's head

The Honest Kitchen talks about feeling a hard knot on a dog's head. If you feel a bump on a dog's head between the ears, it could be what is called a "wisdom bump." It is also called a "knowledge bump" or a "knowledge knot." In times past, this was considered a sign of a dog's intelligence.


Dogs with prominent bumps on their heads are hounds, especially bloodhounds, golden retrievers, Labrador retrievers, and English setters. The hard knot on a dog's head is officially called an "occiput" and it is simply an anatomical feature that makes the skull stronger to provide additional protection for the brain.


When is a lump serious?

How do you know when it is time to consider a hard growth on your dog a serious issue? Tex Vet Pets explains some of the signs that you should look for when determining if the hard growth on your dog is a serious problem.


The lump is fast-growing: A fast-growing lump may need to be removed, whether it is cancerous or not. If a growth does need to be removed, it is easier to remove it when it is small. Also, a large growth may impinge on nerves or some other movement or behavior that could impact your pet's quality of life.

The lump appears to be painful: If you touch your dog's lump and she's obviously in pain from it, it could be an infection.

There's discharge from the lump: Anything oozing from a lump is a sign of infection.

The lump's size changes: A lump that changes size could be a mast cell tumor. These bumps can be itchy. The change in growth is a result of the tumor containing a histamine that swells in size, and then reduces in size as the histamine is released. It is best to remove these types of hard tumors in dogs while they are small.

You see a cluster of smallish bumps that appear suddenly and grow in size: This could be a sign of an allergic reaction.

Types of tumors in dogs

The Diamond Pet Food blog lists 12 common types of lumps and bumps on canine skin that you may likely see.

Lipomas are common, benign tumors filled with fat that lodge under the skin. They are soft, round, and do not hurt your dog. They are also more common in overweight dogs, although any breed can get lipomas.

Histiocytoma Dogs under six years of age get these and they typically go away on their own. A histiocytoma is a red, button-like lump that's thought to be caused by an overactive immune system. These can resemble other forms of cancer, so get it checked to be sure it is a histiocytoma.

Perianal adenoma These are noticeable around your dog's anus. While common, an un-neutered dog is more likely to get these.

Skin tag
This is a common growth in which the skin develops "extra" skin where it shouldn't be. They are harmless and dogs of any breed may develop them.

Sebaceous cyst
This is a fancy name for a plugged oil gland in the skin. In humans, we might call this a large pimple. These are harmless.

This is a sign of infection that can be anywhere in the body under the skin. It is painful and may feel soft and squishy. It can often be caused by an external injury such as an insect bite that gets infected.

This is a collection of bumps similar to a rash. The cause could be an allergic reaction to something like a bee sting or an irritating plant.

Warts (papillomas)
Warts are caused by a virus, and they can pop up anywhere, just like they do in humans. The virus that causes warts is highly contagious between dogs. Warts are usually harmless.

Melanoma is skin cancer. In dogs, these tend to be benign and easy to treat with a surgery to remove them. More aggressive melanomas tend to grow around the mouth and on a dog's legs.

Mast cell tumor
This is the most common skin cancer in dogs. Certain breeds including boxers, Boston terriers, Labrador retrievers, beagles, and schnauzers are more prone to them. These tumors can have a widely variable appearance that can resemble other lumps and bumps. They may be small, or they may be large and hairless.

Soft tissue sarcoma Soft tissue sarcomas usually appear as a firm or semi-firm lump deep under the skin or within muscle. They are usually not painful and are common among middle-aged and older large-breed dogs

Squamous cell carcinoma
This is a skin cancer that is often found in the mouth, skin, or on a dog's nail beds. These are associated with sunlight exposure so they commonly appear in areas on a dog's body where there is less hair.

Always check with your veterinarian before changing your pet’s diet, medication, or physical activity routines. This information is not a substitute for a vet’s opinion.