10 Signs of Cancer in Dogs

Cancer in dogs

The diseases are already quite frightening, but there is something particularly frightening in canine cancers. They depend on us for their health, but cannot tell us when something is wrong. That’s why it’s so important to be on the lookout for signs of cancer in dogs.

It would be wonderful if it were a rare and minor health problem in dogs, but unfortunately, according to the National Canine Cancer Foundation, one in three dogs will develop cancer in their lifetime.

Now let’s look at the warning signs of canine cancer and its most common types. Noticing any of these symptoms does not necessarily mean that your dog has cancer, but there is a good chance he has at least one other health problem, so you should contact your veterinarian immediately if you observe one.
Signs of cancer in dogs

Do you notice one or more signs in this list? Contact your veterinarian immediately.

1. Strange smells

You’ve probably gotten used to your dog’s bad breath, but you should be on the lookout for any unusually bad (or simply different) smell from your dog when you’re close enough to smell his breath.

2. Pale gums

Be sure to check your dog’s gums occasionally for color. Pale gums can be a sign of many health problems in dogs, including cancer. If you notice any changes in this area, contact your veterinarian immediately.

Here’s how to check your dog’s gums:

“lift the jowl so that you can see clearly press on the gums with the ball of your finger Observe the colour of the gum where you pressed.”

In healthy dogs, after pressing their gums, the area should turn white briefly. After about 2 to 3 seconds, the colour should return to its normal pink colour. If not, pay attention to other warning signs and consider talking to your veterinarian about them.

3. Lack of energy

Have there been any significant changes in your dog’s energy level? Lethargy is also one of the most common signs of cancer in dogs. No one knows your dog’s normal behavior better than you, so this is one that your vet can’t always catch.

Does your dog spend less time playing? Do they tire quickly? Do they spend much more time sleeping or do they generally seem uninterested in their usual activities? Pay attention to these, and if you are noticed, start looking for other signs, your dog has cancer

4. Vomiting and diarrhea

Sometimes, when your dog vomits or has diarrhea, it may be due to something coarse but usually harmless, such as eating droppings. Unfortunately, it is also one of the most common signs of cancer in dogs.

If you notice that your dog has diarrhea or vomiting – especially when accompanied by other warning signs from this list – consult your veterinarian immediately. Even if it is not a canine cancer, there may be another health problem that needs to be addressed.


5. Respiratory disorders

As is the case for people, there are many different types of canine cancer. And like people, you need to be aware of the warning signs of lung cancer in dogs. Be careful with your dog while he plays and leads his usual life.

Do you notice any differences in their breathing, such as coughing, wheezing or shortness of breath much faster than normal? Be on the lookout for other warning signs and consider talking to your veterinarian very soon.

6. Moguls or bumps

If you are not already, you should get into the habit of checking your dog’s skin regularly. About once a month is fine. Check by slowly and gently passing your hands over your dog’s body, noting how you feel.

Write down anything that seems unusual or inappropriate, and if this is not the first time you have checked, you will certainly want to investigate something new. Your dog should enjoy these caresses, so don’t be afraid to take your time.

Don’t forget to touch behind their ears and around their faces. If your dog does not want to be touched in certain areas, examine him carefully. Contact your veterinarian immediately if you notice any bleeding or discharge.

7. Unexpected weight loss

If you don’t have a weight loss diet for your dog and you haven’t given him weight control dog food, then unexpected weight loss is one of the most common signs of canine cancer that you should watch for.

Your dog who suddenly loses weight may not be cancer, but if there is no other obvious explanation, there is a good chance that some health problem is the cause and you should contact your veterinarian.


8. Change in appetite

Have you noticed any changes in your dog’s appetite? Do they eat less or are they not interested in the food they normally like? Many health problems for dogs could be the cause, and cancer is unfortunately one of them.

Sometimes it may just be a brief problem of discomfort, or maybe someone else has stolen food from them when you weren’t looking. Pay particular attention to their eating habits whenever you notice a change and talk to your veterinarian immediately if problems persist.

9. Behaviour change

Another sign of cancer in the dogs you will want to monitor is behavioural changes. Does your dog limp, walk or play differently than normal? Is your normally calm dog irritable and barking or slamming even after you?

Dogs, like humans, get angry or lethargic when they don’t feel well. If your dog starts acting weird and there is no obvious reason, there is a good chance he will be sick and you should talk to your vet about it.

10. Injuries or wounds

If you notice any injuries or open sores on your dog that are not healing as quickly as you would have thought or that appear without obvious explanation, contact your veterinarian as soon as possible.

Unexplained wounds or slow healing times can be a sign of something serious – including canine cancer. Feel free to contact a professional immediately who can examine your dog for anything that needs to be treated.

Types of canine cancer

We have already covered the signs of canine cancers, now we are quickly covering the most common types of canine cancers.


This type of canine cancer is found in the lymph nodes or bone marrow and is usually diagnosed in dogs aged 6 to 9 years. It attacks the dog’s immune system and spreads quickly if left untreated.

There are five stages of lymphoma in dogs, each with its own treatment options and prognosis. Canine lymphoma is usually first noticed in a painless but swollen lymph node behind your dog’s neck or knees.


Malignant cancer of the blood vessels, hemanglosarcoma is more frequent in dogs than in any other species. It is most often found in the spleen, liver and heart, but it can spread to any organ or occur just under the skin.

Unfortunately, there are no obvious warning signs of hemanglosarcoma and it is often not found until it is at an advanced stage. This type of canine cancer is most often found in large breeds such as German shepherds or golden retrievers.


A type of skin care that you have probably heard of because of its frequency in humans, melanoma is most often found in or around a dog’s mouth or lips. It can also be found in their nail beds, foot pads and eyes.

In dogs, melanoma can be particularly aggressive, extending from the skin to the dog’s organs. Early signs of melanoma in dogs include swelling of the legs, a draining eye or sores in or around the mouth.

Mast cell tumours

Found in the skin and other tissues such as the respiratory tract or intestines, mast cell tumours attack the dog’s immune system by turning normal protective enzymes and histamines against the dog.

Mast cell tumours are very common in older dogs. Mixed breeds should be particularly on the lookout, as should boxers, Boston burrows, beagles and schnauzers. The earliest sign is usually skin lesions, with agitation caused by discomfort also common.


Bone cancer, about 85% of osteosarcoma tumours are malignant and develop very quickly. It is most commonly found in large breed dogs aged 4 to 7 years.

Early signs are swelling and lameness. The most threatened breeds are the Great Danes, Irish setters, Doberman Pinschers, Rottweilers, German Shepherds and golden retrievers.

Breast cancer

Breast cancer is most often found in bitches that have not been sterilized or have only been sterilized after the age of 2 years. Approximately 50% of breast tumours in dogs are malignant and have metastases (spread) at the time of surgical removal.

It is difficult to detect, as breast tumours usually appear only as a small nodule on or around the dog’s nipple.

Be aware of these signs of cancer in dogs. If you notice one or more signs, you should contact your veterinarian immediately. Cure rates have never been so good and improve even more with early detection.

Best wishes to you and your puppy, and don’t forget to pin them down or share them so you can help other dog parents learn about the warning signs of canine cancer!



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