Does Your Dog Have Cancer? The Warning Signs You Need to Look Out For

Unfortunately, cancer is the No. 1 cause of natural death among dogs, with 50% of canines over the age of 10 developing some form of it. Certain breeds are more likely to get sick than others. If you have a purebred, it’s important to be especially vigilant as your pup ages.

The good news: Half of all dog cancers can be cured if they’re detected early enough. Ahead, discover the most common warning signs that your dog may have cancer. And take special notice if your dog develops one kind of abnormal growth (on page 10).

1. Wounds that won’t heal

sick dog wearing plastic collar

Have a vet check the wound. | Fly_dragonfly/iStock/Getty Images

Festering wounds are a sign that there’s abnormal cell growth happening in your dog’s body. An open wound or lesion that doesn’t scab over or heal should be checked out by a vet immediately.

Next: If your dog falls, there could be a problem.

2. Collapsing

Greater Swiss mountain dog

It could be a sign of weakness. | iStock/Getty Images

It’s not normal for your dog to suddenly fall down from weakness. As Jake Zaidel, DVM at Malta Animal Hospital in upstate New York told Reader’s Digest, “I see this particularly in large breed dogs — even if they fall down and seem better the next day, bring them in because it could signal a tumor of the spleen.”

Next: Don’t assume your dog has a cold.

3. Coughing

Dog leaning away

A persistent cough isn’t a good sign. | fotoedu/iStock/Getty Images

A few coughs here and there shouldn’t be cause for alarm, especially with small breeds who are prone to windpipe issues. But if you notice a persistent cough in your dog that lasts several days, then it’s time to visit your vet. It could be an early sign of lung cancer.

Next: This obvious sign could point to stomach cancer.

4. Rapid weight loss

Dry Dog Food in a Stainless Steel Bowl on Ceramic Tile Floor

Get your dog checked if he suddenly loses his appetite. | herreid/iStock/Getty Images

You already know your dog loves to eat — so if he stops, you should be concerned.

According to Dr. Zeidel, the number one symptom of a gastrointestinal tumor in your dog is rapid weight loss.  Many dogs stop eating when they contract this form of cancer.

Even if your dog is still maintaining his appetite but is losing weight, it’s a good idea to get him checked out. Some cancers cause weight loss even if your dog is eating normally.

Next: Here’s an overlooked place you should always check on your dog.

5. Mouth changes

Beautiful labrador retriever dog in the park,

Look for signs of oral cancer. | sanjagrujic/iStock/Getty Images

It may not be top of mind to check inside your dog’s mouth, but you should make it a habit to ensure you catch any indicators of oral cancer. Many people miss the warning signs because they forget to look for abnormalities and don’t notice them until it’s too late.

Sores, lumps, odors, bleeding, and gum color changes can all be signs of mouth cancer, especially in older dogs.

Next: This should never happen to your dog.

6. Nosebleeds

A wolfdog is seen during a demonstration

A nosebleed could be a sign something major is wrong. | Jonathan Nackstrand/AFP/Getty Images

You might get a harmless nosebleed when the air is dry. But when your dog has a nosebleed, it’s an indication of a bigger problem.

For a younger dog with a nosebleed, the likely cause may be an injury. But older dogs that get a nosebleed could have nose cancer.

Next: If this symptom persists, call the vet.

7. Changes in bathroom habits

Young woman with Beagle dog in the park

Always notice changes in his bathroom habits. | SbytovaMN/iStock/Getty Images

There’s no need to panic the next time you notice that your dog has diarrhea — he most likely got into your candy stash when you weren’t looking. But if you notice a long stretch of loose stools, bloody urine or poop, or if he’s struggling to go or asking to go out more often than usual, it’s time to schedule a vet visit immediately.

Next: This could be a symptom of tumors.

8. Discharge

Happy vet holding french bulldog puppy

Let a vet know about any continuous discharge. | hedgehog94/iStock/Getty Images

Continuous discharge from the nose or eyes could signal facial or eye tumors lurking beneath the surface. Always mention these types of concerns to your vet.

Next: A brain tumor often presents this way.

9. Seizures

sick dog on the floor

Contact a vet right away. | Chalabala/iStock/Getty Images

A brain tumor in dogs often presents in the form of seizures, especially in older dogs. If you notice your dog having uncontrollable bursts of activity such as chewing or leg jerking, or if you see him foaming at the mouth, you need to call your vet immediately.

Next: This kind of growths are a huge indicator of canine cancer.

10. Tumors or abnormal growths

sick dog lying down

Know the signs of canine cancer. | sanjagrujic/iStock/Getty Images

One of the first things people think of when they hear the word cancer is, “tumors.” However, not all lumps you find on your dog are cancerous.

Some breeds are more likely than others to develop fatty tumors or other harmless lumps on their bodies. It is vital to get them checked out to ensure they’re benign, though. Be sure to keep an eye out for any new growths and never ignore a potentially cancerous tumor on your dog.

Next: You might want to notify your groomer to watch out for this, too.

11. Skin changes

dog scratching

Habitually check your dog’s skin. | dimarik/iStock/Getty Images

It can be hard to detect changes in your dog’s skin underneath their fur. Make it a habit to give your canine companion a rubdown and systematically look for sores, lesions, or other changes in the color or appearance of his skin and take those findings to your vet.

Next: Don’t ignore when this common thing happens to your dog.

12. Weight gain


Weight gain could be a serious problem. | YakobchukOlena/iStock/Getty Images

Whether it’s from an increased appetite or bloating, unexpected and rapid weight gain could signal a real problem. It’s always best to get it checked out by a professional immediately.

Next: Your dog may be trying to tell you something.

13. Pain or discomfort

sick dog under a blanket

Pain is an indicator something is wrong. | igorr1/iStock/Getty Images

Whining or crying when you touch a certain spot is a clear indicator that your dog has an issue. Mouth tumors might make it visibly difficult for your dog to eat. Schedule a vet visit right away when you notice this problem with your pooch.

Next: Pay close attention to this behavior change.

14. Lameness

limping dog

Contact a vet if you notice any changes in how your dog is walking. | CriDam/iStock/Getty Images

If you notice your dog favoring one leg or another, or any changes in gait, it could be a sign of bone cancer. Head to the vet for a definitive diagnosis if you notice this change in behavior.

Next: This is a scary side effect of cancer.

15. Difficulty breathing

Labrador panting outside

This could turn into an emergency. | eurobanks/iStock/Getty Images

If you notice your dog struggling to breathe or wheezing, it’s a cause for concern and could be an early sign of canine cancer. You know what to do — call the vet.

Next: Here’s what happens after your dog gets diagnosed.

16. Your dog has cancer — now what?

Man holding dog

The earlier the cancer is detected, the higher the chance of survival. | JamesYetMingAu-Photography/iStock/Getty Images

Cancer doesn’t necessarily mean a death sentence for your dog. Most types of canine cancer respond to treatments such as radiation therapy, chemotherapy, and surgery. Some medical facilities are even testing immunotherapy tumor vaccines.

The faster you can detect and diagnose cancer, the better off your dog will be. Pay attention for any of the common symptoms and don’t be afraid to visit the vet even if you just notice your dog is acting a little strangely. Your vigilance could save his life.

Read more: The 15 Least Healthy Dog Breeds

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