Get

In Your Inbox

Dogster is reader-supported. When you buy via links on our site, we may earn an affiliate commission at no cost to you. Learn more.

Are All Tumors Cancerous in Dogs? Our Vet Explains the Differences

Share

dog in vet clinic

A tumor—in a dog or another animal—is a swelling due to the unregulated growth of tissue cells. While that may sound bad, it doesn’t necessarily mean cancer. Tumors can either be benign (noncancerous) or malignant (cancerous). Knowing which type your dog has will require a veterinary diagnosis. It’s nearly impossible to discern a cancerous tumor from a noncancerous tumor just by looking at it, so it’s best to always see your vet any time you notice a new growth on your dog.

divider single dog paw oct 2024

Tumors in Dogs

It is important to understand how different tumors form in the first place. The body is all about balance: If something goes in, something has to come out, and if you use up something, it has to be replaced, and so on.

The same principle goes for tissue growth. Normal tissue cells are actively dividing and reproducing to make new cells. Conversely, other tissue cells are dying and thus, need to be replaced. To maintain a healthy balance, bodily tissues need to reproduce a new cell to replace every dying cell. But sometimes, that balance gets out of whack, and the tissue cells start reproducing more rapidly than they are dying off. Therefore, you get an abundance of new tissue that creates a lump, mass, or tumor.

Depending on the type of cells that are overly multiplying, that tumor may keep to itself or look to relocate elsewhere in the body.

sick dog with veterinary assistant doing examination of his head tumor.
Image Credit: sarocha wangdee, Shutterstock

What Is the Difference Between Benign and Malignant Tumors?

Just because a group of cells gets overly excited and starts multiplying out of control doesn’t mean that they are cancerous. Different types of cells may simply multiply, creating tumors that stay put. These are benign tumors. They don’t spread to other parts of the body or even get into the healthy tissues around it. While they can grow large and displace surrounding tissue, they don’t actively invade it.

Conversely, malignant tumors tend to spread around. They will invade the surrounding tissues and disrupt their normalcy, often creating a great deal of damage. Certain ones also spread to other areas of the body, like the lymph nodes, liver, and lungs.

As you can imagine, a tumor that keeps to itself is less likely to destroy normal surrounding tissues than one that is more invasive. That’s the difference between noncancerous and cancerous tumors.

Malignant tumors need to be treated immediately to minimize their spread and resulting damage. That said, benign tumors will sometimes also need veterinary care.

If you are concerned about the health and well-being of your pet, seek veterinary advice for the best course of action.

If you need to speak with a vet but can't get to one, head over to PangoVet. It's our online service where you can talk to a vet online and get the advice you need for your pet — all at an affordable price!

PangoVet_Mention-in-Content Savings V1

Can a Dog Have a Non-cancerous Tumor?

It’s estimated that 25% of dogs will develop a tumor at some point in their lives and that malignant tumors are about twice as likely to develop as benign ones.1 Of course, this proportion depends on the type of tumor. For example, most skin tumors tend to be benign. So, it is completely possible for your dog to develop a tumor that isn’t cancerous.

Still, even noncancerous tumors may require treatment to prevent sometimes severe complications, so be sure to see your vet if you notice a new lump or bump on your dog.

close-up photo of a dog with lumps on his skin before the surgery
Image Credit: Todorean-Gabriel, Shutterstock

How Do I Know If My Dog’s Tumor Is Cancerous?

Cancerous tumors can look similar to noncancerous tumors, so it’s suggested that you have your vet check out any new lump on your dog. While a veterinary diagnosis is needed to definitively determine whether a tumor is cancerous, there are a few telltale signs that you may recognize at home.

Malignant tumors tend to grow more quickly than benign ones. So, if you notice a small bump one day that turns into a large bump within a matter of days, it may be cancerous. They also tend to quickly change in color, shape, and texture. A skin-colored lump that suddenly turns black or purple may be a red flag for cancer. Discharge from the lump may be another possible indicator.

If you notice a new lump, particularly if it’s growing and changing rapidly, see your vet as soon as possible. They will be able to take a sample of the tumor to find out what cells are growing there and determine whether it’s cancerous. Sometimes this requires them to send a sample to a different lab for a second opinion.

divider single dog paw oct 2024

Conclusion

Finding a tumor on your dog is never a good time. That said, while no tumor is considered normal or good, you should know that tumors can be either cancerous or noncancerous, and there’s no way to tell without the help of a veterinarian. So, be sure to seek professional help whenever a new lump or bump pops up or if you start noticing changes in your dog’s appetite, behavior, or elimination habits.


Featured Image Credit: Pickadook, Shutterstock

Want content like this delivered to you?

Sign Up For Our Newsletter

News, insights, expert advice, and everything dog

* By submitting, you agree to our Terms & Conditions and Privacy & Cookies Policy.




How useful was this post?

Click on a star to rate (you can leave written feedback after clicking submit)

Help us improve Dogster for pet parents!

Your feedback really matters.

What did you like about this post? Also how can we improve it?

Join the conversation

Leave a Reply

You’re very welcome to leave a comment or question. Please know that all comments must meet our community guidelines, and your email address will NOT be published. Let’s have a positive and constructive conversation.


Talk With A Vet Online

Peace of mind,
anywhere, anytime

Affordable vet advice

Dogster’s Weekly Photo Contest Winners: My Best Trick (April 16, 2026)

Every week our team gets the privilege of sorting through our readers photos to choose what dogs will win this weeks contest! See...

From Grief to Gratitude: How One “Potato” and a Road Trip Changed Everything

The “COVID Puppy” phenomenon is a well-known chapter of the pandemic, but for Alexis Walling, the arrival of a tiny, wrinkled English Bulldog...

Why Dogs Play Too Rough — And the Simple Fixes That Prevent It From Becoming a Problem

A dog that plays too rough with others is a problem that builds fast. One minute, the dogs are running and chasing, the...

Ricky Gervais Says: It’s Time to Release The Dogs

As activists prepare to carry out the biggest Open Rescue in the history of animal welfare, Ricky Gervais says, “it’s time to release...

More related

33 Cool Dog Products You Can Grab Today (2026 Guide)

People love their dogs, so there is no shortage of dog products on the market. Pretty much anything you could ever think of,...

Why Dogs Are Better Than Cats: 14 Reasons to Love Our Pups

If you’re a dog parent, you know dogs are better than cats. After all, your canine companions brighten your day, keep you active,...

American Bullnese: Info, Pictures, Care & More

The American Bullnese is a relatively new member of the so-called designer dogs. This pup brings the regal appearance and manner of the...

6 Best Flea & Tick Sprays for Dogs in 2026 – Reviews & Top Picks

You might not have to worry about fleas and ticks during the cold winter months, but once spring starts to roll around, these...

Keep reading

Can Dogs Eat Sour Cream? Vet-Approved Facts & FAQ

There are several tasty dishes that we enjoy by themselves, but the moment that you add a dollop of sour cream, the dish is transformed into something magical! It’s only natural that you want to share your food with your...

Can Dogs Eat Sour Cream

Can Dogs Eat Duck? Vet-Verified Health Benefits

It’s hard to resist when your dog is begging for a scrap or two from your dinner plate. But before giving your pet any people food, you should be sure that it’s safe to do so. Some human foods are...

Can Dogs Eat_Duck

What Fruits Can Dogs Eat? 13 Vet-Approved Options

Summer is right around the corner, and if you’re anything like me, you’re probably excited about all the in-season fruits you’ll be able to eat soon. You might also be curious about which fruits, if any, are safe to offer...

Labrador retriever dog eats watermelon from hands

Can Dogs Be Vegetarian? Vet-Verified Nutrition & Health Facts

Dogs are considered omnivores, or facultative carnivores, meaning they can digest and utilize both animal and plant-based foods in their diet. However, did you know dogs can be fed a vegetarian diet and thrive? Dogs do not need meat in...

The dog sits near a bowl of food and licks his tongue, dry food and fresh vegetables and fruits

Can Dogs Eat Cinnamon Toast Crunch? Vet-Verified Nutrition Facts & FAQ

Breakfast is not only the most important meal of the day, but you may think it’s the best one, too. Whether you’re chowing down on pancakes, bacon, oatmeal, or eggs, it’s hard not to love this meal. However, what’s a...

Can Dogs Eat Cinnamon Toast Crunch

14 Best Large Breed Puppy Foods in 2026 – Reviews & Top Picks

All humans may be created equal, but not all puppies grow at equal rates or end up the same size when they are done growing. If you have lost your heart to a large or giant breed puppy, there are...

german shepherd puppy eating dry food outdoors

Can You Judge Dog Food Solely by Its First Ingredient? Facts & FAQ

Judging dog food can be overwhelming. There is a lot that you need to keep in mind when checking out dog food. You may be tempted to shorten the process by only looking at the first ingredient. While you can...

Portrait of woman with small dog choosing preserves in pet shop

Can Dogs Eat Syrup? Vet-Verified Nutrition Facts & Info

Our canine companions are pros at begging our food off us, and they aren’t picky either. Our pups are more than interested in eating everything we eat. But not all people foods are healthy for dogs; in fact, some foods...

Dogster-Can-Dogs-Eat-Syrup

Love Dogs? So Do We! Join the Dogster Community

Stay informed with expert pet care insights delivered straight to your inbox! Discover professional guidance on animal behavior, feeding tips, trusted product picks, and much more.




Sign up for the Dogster Email Newsletter