Vets Reveal The Top Signs Of Cancer In Dogs

Signs Of Cancer In Dogs

Let’s face it … the statistics aren’t encouraging. 

There are 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.

So, 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 I talked to some leading holistic vets about possible signs of cancer in your dog. 

These signs don’t always mean your dog has cancer … but it’s a good idea to ask your holistic vet about them.

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

Cancer In Dogs

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

“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.”

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. The good news about that is … it’s not a painful disease. 

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. 


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. 

Breeds who seem most prone to lymphomas include … 

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

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. 


Osteosarcoma is the most prevalent form of bone cancer. It represents about 85% of bone cancers in dogs.

Taller, heavier dogs are most at risk for osteosarcoma. And it’s more common in middle aged dogs.  

  • Great Danes
  • St Bernards
  • Irish Setters
  • Dobermans
  • Rottweilers
  • German Shepherds
  • Golden Retrievers
  • Scottish Deerhounds (who are genetically predisposed to the disease)

The first sign you’ll likely see for this cancer in your dog is persistent lameness or swelling. 

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.

Some breeds more at risk include …

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

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.

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 its malignant, the histiocyte cell spreads aggressively in several different places at once, such as …

  • Spleen
  • Lymph nodes
  • Lung
  • Bone marrow
  • Skin
  • Brain
  • Joint tissue

It’s more prevalent in certain breeds, including …

  • Flat-coated Retrievers
  • Bernese Mountain Dogs
  • Rottweilers
  • Golden Retrievers

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 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.

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. 

Mouth and Nose Cancers

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
  • Changes in skin color
  • Mouth problems like drooling, swelling, loose teeth or difficulty 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. 

Breeds more prone to testicular cancer include

  • German Shepherds
  • Weimaraners
  • Shetland Sheepdogs
  • Boxers

Cryptorchid dogs – who have a retained testicle ­– have higher risk of testicular cancer. 

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

Managing Cancer Risks In Dogs

Before I tell you what the holistic vets said about signs of cancer in dogs … I wanted to mention a few risk factors. You can manage some of these risks! 

There are obviously some environmental or genetic risks you can’t control. But there are other cancer risk factors you can reduce for your dog.


Vaccines aren’t safe … and there are no safety studies proving they are! 

There are several ways vaccines can contribute to cancer. 

So … don’t give any unnecessary vaccines. Do your research before you go to the vet, so you’re prepared to politely say “no thank you.”

And don’t let your vet convince you every vaccine is required annually or even every 3 years. Because the only vaccine required by law is rabies. And that’s every 3 years (after an initial 1 year shot). 

We can’t advise you to break the law … but again, do the research and try to make the best decision for your dog

RELATED: Why you shouldn’t volunteer your dog for cancer vaccine research …


Diet is probably the single most controllable influence on your dog’s health. 

And it’s also one of the biggest factors in managing cancer.

Kibble is one of the worst things you can feed your dog if you want to avoid cancer. 

  • Kibble is full of starches. Starches convert to sugar in your dog’s body. And sugar feeds cancer cells. So … feeding a starch-free and sugar-free diet helps “starve” cancer cells. 
  • Kibble contains aflatoxin molds, which are carcinogenic.
  • Kibble is full of synthetic additives, including carcinogenic dyes and preservatives.
  • Kibble is processed at very high temperatures. The heat produces carcinogenic substances called heterocyclic amines and acrylamides.  

Read more about why you should avoid kibble.

So … feed real food. Give your dog a fresh, whole food, raw meat-based diet.  

And if your dog does get cancer … work with your holistic vet on diet adjustments and supplements that’ll support his health even more. 

Don’t consult conventional vets or oncologists about diet. They’re not taught about nutrition in vet school. So they won’t give you good advice!


You may not think twice about filling your dog’s water bowl straight from the tap. 

But (unless you have well water) … your tap water contains chemicals and contaminants like …

  • Fluoride
  • Pharmaceuticals
  • Lead
  • Asbestos
  • Pesticides
  • Herbicides

Any holistic vet will agree … always give your dog spring or filtered water. 

Toxins And Chemicals

You can’t avoid every environmental toxin. 

If you live in the city, your dog is going to breathe car exhaust fumes that can contribute to cancer. And your neighbors may use carcinogenic pesticides like Roundup on their yards. City parks and golf courses also use chemicals to keep the grass lush and green. 

But you can avoid what you use in your home. There are toxic chemicals in things like … 

Remember your dog lies on the floor and walks on it in bare feet.  He’s much more exposed than you are to any chemicals you use to clean. 

So avoid chemical products in your home and yard as much as you can!

Avoid Spay/Neuter

This is always a hot topic … and controversial, whoever you talk to.

But spaying or neutering your dog can have devastating effects on your dog’s long term health  … and his cancer risk. 

Spaying and neutering statistics speak for themselves. The procedures lead to …

If you must spay or neuter your dog, do it as late as you can. Early spay/neuter increases the risk of many diseases, including cancer. 

Want more tips on avoiding cancer in your dog? Dr Demian Dressler is well known as The Dog Cancer Vet and author of the best seller “The Dog Cancer Survival Guide.”

Read Dr Dressler’s detailed recommendations.

Vets Talk About The Signs Of Cancer In Dogs

So now (finally!), here’s what some of our favorite holistic vets said …

… when we asked them for the most common signs a dog may have cancer. 

I want to start with Dr Marty Goldstein’s comments. Keep his thoughts in mind if you find yourself fretting about every tiny change you notice in your dog. 

Martin Goldstein DVM

Featured in the documentary The Dog Doc, and author of The Nature of Animal Healing.

“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.”

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 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.”

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.”

Read Dr Billinghurst’s thoughts about chemotherapy and radiation 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

So now you have varying professional opinions from top holistic vets on how to monitor your dog for signs of cancer. 

My personal thoughts?  

Keep an eye on your dog’s health and monitor him for significant changes. But don’t spend your time over-worrying about your dog … because that can create stress that will be negative for both of you. 

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