Vets Reveal The Top Signs Of Cancer In Dogs

signs of cancer in dogs
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The statistics aren’t encouraging. With 65 million dogs in the US, each year there are about 6 million new dog cancer cases. And half of dogs over 10 die from cancer. It’s every dog owner’s worst fear. So you want to be sure you don’t miss the signs your dog might have cancer.

First, let’s look at what types of cancers dogs get … and which breeds are most susceptible.

What Are The Common Types Of Cancer In Dogs?

Dr Charles Loops is a homeopathic veterinarian who specializes in cancer cases. He says there can be a general predisposition to cancer in some breeds and families. 

“We see more cancer in general in Boxers, Giant Schnauzers, Bernese Mountain Dogs, Irish Wolfhounds, and Dobermans. There are also familial tendencies toward cancer in many individual lines of dogs of various breeds, large and small.”

Charles Loops DVM

So … what are the most common types of cancer in dogs? And which cancer might your breed be prone to?


Hemangiosarcoma is a cancer of the blood vessel lining. It occurs more commonly in middle aged or older dogs, as well as certain breeds. Hemangiosarcoma represents 0.2% to 3% of all canine cancers. Breeds who most often get hemangiosarcoma include …

  • Golden Retrievers (lifetime risk is 1 in 5)
  • German Shepherds
  • Labrador Retrievers
  • Boxers
  • Rottweilers
  • Dobermans
  • English Setters
  • Flat-Coated Retrievers
  • Portuguese Water Dogs
  • Skye Terriers
  • Whippets

Other breeds can be prone to skin hemangiosarcoma. These are usually pink-skinned dogs with sparse coats, like Dalmatians, Whippets, Basset Hounds, Pit Bulls, Boxers.

Unfortunately, hemangiosarcoma is a very difficult cancer to spot. Dogs often don’t have any visible signs or symptoms. That does mean that it’s not a painful disease for your dog. 

Mast Cell Tumors

Mast cells are part of your dog’s immune system. They stem from your dog’s response to allergies or parasites. Not all mast cell tumors are malignant.  Mast cell tumors are usually on the skin … but sometimes in other organs. Dogs who suffer from allergic reactions may be more likely to develop mast cell tumors. Boxers, Pugs and Shar-Peis seem especially susceptible to mast cell tumors. 


Lymphoma is most common in middle aged dogs, from 6 to 9 years old. But it can happen in younger dogs too. Dogs with compromised immune systems are more susceptible to lymphoma. Exposure to herbicides or industrial chemicals are other risk factors. 

Lymphoma often first appears as lymph nodes (glands) under the neck. Other places are in front of the shoulders or behind the knee. Some forms of lymphoma may be internal and you won’t feel them.  Breeds who seem most prone to lymphomas include … 

  • Airedale Terriers
  • Basset Hounds
  • Boxers
  • Bulldogs
  • Scottish Terriers
  • St Bernards


Osteosarcoma is the most prevalent form of bone cancer. It represents about 85% of bone cancers in dogs. The first sign you’ll likely see for this cancer in your dog is persistent lameness or swelling. It’s more common in middle aged dogs. Taller, heavier dogs are most at risk for osteosarcoma … 

  • Great Danes
  • St Bernards
  • Irish Setters
  • Dobermans
  • Rottweilers
  • German Shepherds
  • Golden Retrievers
  • Scottish Deerhounds (genetically predisposed)

Brain Tumors

There are several different kinds of brain tumors in dogs. The most common forms are:

  • Meningioma – tumor in the membranes around the brain and spinal cord, called meninges. Dolichocephalic (longer nosed) breeds like Collies are more prone to these tumors. 
  • Glioma – tumor in the brain’s supportive tissues. These tumors are more common in brachycephalic (flat faced) breeds.

Brain tumors are more likely in middle aged dogs, 7 or older. Key signs of brain tumors in dogs can be: 

  • Seizures
  • Behavior changes
  • Unsteady walking
  • Vision loss
  • Neck or head pain (shown by head tilting) 

Bladder Cancer

Bladder cancer is fairly rare … about 1-2% of all dog cancers. There are two formal names for it: Transitional cell carcinoma (TCC) or urothelial carcinoma. Lawn chemicals are a known risk factor for bladder cancer in dogs. Bladder cancer is slow to develop.  Your dog may not show signs of this cancer for 3 to 6 months. Urinary obstruction and bleeding are common signs. 

Some breeds more at risk for bladder cancer include …

  • Scottish Terriers
  • West Highland White Terriers 
  • Beagles
  • Shetland Sheepdogs
  • Wire Fox Terriers
  • American Eskimos 

Mammary Carcinoma

This is breast cancer. It can happen in any female dog, though intact dogs are at higher risk. About 40-50% of female mammary tumors are malignant. Male dogs can occasionally get mammary tumors as well … and when they do, they’re usually malignant.  High fat diet and obesity may increase the risk of mammary tumors. 

Malignant Histiocytosis

This is a less common dog cancer. It comes from abnormal levels of a type of white blood cell … called the histiocyte. The histiocyte is part of the immune system that lives in the body’s connective tissues. Its job is to consume invading organisms. When it’s malignant, the histiocyte cell spreads aggressively in several different places at once, like the spleen, lymph nodes, lungs, bone marrow, skin, brain and joint tissue.

It’s more prevalent in certain breeds, including Golden or Flat-coated Retrievers, Bernese Mountain Dogs, Rottweilers.

Squamous Cell Carcinomas

These are skin cancers in the squamous layer (epithelium) of outer skin cells. Squamous cell carcinomas are most often in the mouth … or the nail beds of the toes (called sublingual tumors). They account for 5% of all skin cancers in dogs. They’re more common in dogs who live at high altitudes … or spend a lot of time in the sun. Breeds that may be more predisposed to squamous cell cancers have light skin and hair, including …

  • Scottish Terriers
  • Pekingese
  • Boxers
  • Poodles
  • Norwegian Elkhounds
  • Dalmatians
  • Beagles
  • Whippets
  • White English Bull Terriers

Large breed black dogs are more prone to squamous cell carcinomas on the toes. Early signs of this cancer may be a raised bump or white skin mass on your dog. Sometimes these masses will ulcerate and bleed.  In sublingual tumors, toenails may fall off or get infected.

Mouth and Nose Cancers

These are common forms of cancer in dogs, especially in the mouth. Nasal tumors are locally aggressive. They often spread to surrounding tissues more than to other body parts. Symptoms of mouth cancer include mouth swelling, excessive drooling, bad breath or difficulty eating. 

Breeds more prone to oral cancers include …

  • Cocker Spaniel
  • German Shepherd
  • German Shorthaired Pointer
  • Weimaraner
  • Golden Retriever
  • Gordon Setter
  • Miniature Poodle
  • Chow Chow
  • Boxer

Signs of nasal cancer in dogs are abnormal discharge, bleeding, snoring or trouble breathing. Long-nosed breeds and senior dogs are at higher risk. 


Melanomas come from pigment-producing cells called melanocytes. So they are more common in dark-skinned dogs. Melanomas can take different forms:

  • Oral (mouth) – 80-85% of melanomas, often with metastasis
  • Subungual (nail bed) – 15-20% of melanomas
  • Cutaneus (skin) – often, but not always, benign
  • Eyes (Ocular) – usually benign

Signs of these melanomas can be lumps or bumps, changes in existing growths or skin color … or mouth problems like drooling, swelling, loose teeth or trouble eating.


Testicular cancer can happen in any intact male dog, but usually in older dogs. The risk of testicular cancer is often used as an excuse to persuade you to neuter your male dog. Don’t fall for that … because there are many health reasons not to neuter him. And if your dog does develop it, most cases are easily remedied by castration at that time.  Cryptorchid dogs – who have a retained testicle ­– have higher risk of testicular cancer. 

Breeds more prone to testicular cancer include …

  • German Shepherds
  • Weimaraners
  • Shetland Sheepdogs
  • Boxers

 Signs of testicular cancer in dogs include scrotal swelling or lumps.

RELATED: Read Dr Demian Dressler, The Dog Cancer Vet’s recommendations on how to prevent cancer …

What Are The Signs Of Cancer In Dogs?

If you’re afraid this could happen to your dog … you’re one of millions of dog owners with the same fear. It’s easy to be too vigilant. And then you worry that any little lump, bump or minor ailment means your dog has cancer. (See what Dr Marty Goldstein says about this below). 

But you do need to know what to be aware of … so that if your worst nightmare happens, you can catch it quickly. So we asked some leading holistic vets about possible signs of cancer in your dogThese signs don’t always mean your dog has cancer … but, if you notice any of them, it’s a good idea to ask your vet to check your dog.

Here’s what some top holistic vets who treat cancer said when we asked them for the most common signs of cancer in a dog. 

Martin Goldstein DVM

Featured in the documentary The Dog Doc, and author of The Nature of Animal Healing. Dr Goldstein offers some important advice … especially if you’re a worrier!

“I don’t like giving people things to look for … because then they start looking for them. The mind is very powerful. And the bond between humans and animals is so strong … that when people start to look for cancer, they can actually create it. It’s more important to observe your dog for “what is.” Don’t look for negative things … look for how great your dog is doing! That’s very, very important.”

Marty Goldstein DVM

Dr Goldstein offered this list of big signs a dog may have cancer:

  • Lumps
  • Labored breathing
  • Severe lethargy
  • Pale gums 
  • Consistent lameness 

Richard Pitcairn DVM PhD

Author (with Susan Pitcairn) of Natural Health for Dogs and Cats. Founder of The Pitcairn Institute of Veterinary Homeopathy

Dr Pitcairn says that finding a bump or enlargement is often the most likely way you’ll detect a tumor. Watch for non-specific signs your dog isn’t feeling well … like:

  • Lack of appetite
  • Unexplained weight loss and wasting … called cancer cachexia. This can happen in late stage cancer, or in dogs treated with chemotherapy

Ian Billinghurst BVSc

Creator of the BARF Diet. Author of Pointing The Bone At Cancer; Give Your Dog a Bone, Grow Your Pups With Bones and The BARF Diet.

Dr Bilinghurst explains … “cancer is the master of mimicry.” Apart from obvious surface lumps and bumps, other signs include. 

  • Weeping sores that don’t heal
  • Lameness that won’t go away
  • Neurological signs that don’t improve with treatment

Or, says Dr Billinghurst, it could mean something else entirely …

“The trouble is with the more insidious cancers that pretend to be something else. By the time they’re diagnosed, it’s often too late.”

Dr Ian Billinghurst

Like Dr Pitcairn, Dr Billinghurst warns of one telling sign of cancer at an advanced stage. It’s cancer cachexia – the wasting cancer syndrome.

“Now we watch helplessly as the cruelly futile medical merry-go-round accepts another rider.”

RELATED: Read Dr Billinghurst’s opinion on chemo and radiation therapy for dogs with cancer … 

Dee Blanco DVM

Homeopathic veterinarian at DrDeeBlanco

Dr Blanco notes that emaciation is a common sign of cancer … especially if it happens rapidly. Undiagnosable disease is often a warning sign. If your dog needs a lot of complex, invasive, expensive diagnostics … that could suggest cancer. Statistically, any dog over six years old is at risk for cancer, especially if they’re …

  • Eating a commercial diet
  • Receiving frequent vaccinations and drugs 
  • Exposed to pesticides and other toxins

Patricia Jordan DVM

Author of Vaccinosis – The Mark Of The Beast Hidden In Plain Sight.

Dr Jordan advises watching for any changes in your dog after vaccination. 

“In my experience … common signs of cancer like lumps and lameness often follow vaccination.”

Other signs may include …

  • Weight loss
  • Coughing
  • Bleeding from the nose (nasal cancer)
  • Bulging eyes (tumor behind the eyes)

Be especially aware if you vaccinate or use pharmaceutical drugs regularly. Also, if you’re a smoker… secondhand smoke can affect your dog … even if you smoke outdoors! All these things can increase the likelihood your dog will develop cancer.

Judy Jasek DVM

Holistic vet at Animal Healing Arts

Dr Jasek treats a lot of cancer cases holistically. She explains that she tries not to take an “attack the cancer” or “seek and destroy” approach.  Instead her goal is to support the patient, keep the cancer from growing … and keep a good quality of life. And she applies this positive, supportive approach … no matter what kind of cancer the pet has. Here are some things to keep an eye on …

  • Lumps or unexplained swelling.
  • Behavioral changes.
  • Not eating.
  • Digestive changes, frequent diarrhea or vomiting.
  • Abnormal bleeding (in vomit, stool, or nasal discharges).
  • Sudden lethargy – even if your dog is getting older.
  • Dogs with itchy skin ­ – another sign of chronic inflammation.
  • Any chronic problem – means your dog’s body isn’t functioning normally.
  • Enlarged lymph nodes.
  • Don’t ignore symptoms and let them go on. Especially avoid using drugs to suppress symptoms. This is just a Band-Aid and will lead to deeper problems.
  • Be especially alert to changes if your dog is … over-vaccinated, eats kibble, or gets pharmaceutical heartworm, flea and tick meds.

If you want to be more proactive … 

  • Monitor bloodwork – this is tricky because changes can mean many things. But follow up on issues like elevated calcium, white blood count or lymphocytes … or very low blood glucose.
  • Check for inflammatory markers – any time the body is inflamed, it predisposes your dog to cancer. All disease begins with inflammation. VDI is a lab that offers tests for various wellness markers, including …
    • Inflammatory markers like C-reactive protein
    • Vitamin D levels
    • Vitamin B12 levels
    • Cancer risk assessment

Now you have some professional opinions from top holistic vets on how to monitor your dog for signs of cancer. Keep an eye on your dog’s health and follow up on any significant changes.


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