2021 Guide to Cancer in Dogs: Common Types, Symptoms, Treatments


2021 Guide to Cancer in Dogs: Common Types, Symptoms, Treatments

A cancer diagnosis for your pet dog can be just as devastating as getting one yourself. Unfortunately, cancer in dogs is quite common—with proper treatment and care, your dog can fully recover and live a happy life. 

Let’s look at some common types of cancers, including cancer of the bone, liver, spleen and skin. By no means is this list exhaustive, but it will give you some insight into the diagnosis and prognosis of common cancers that affect dogs.

Key Takeaways

  • Cancer is quite common among dogs.
  • With proper care and treatment from a veterinarian, your dog can recover and live a full life.
  • Different types of cancer can affect your dog. Some are fatal while others are benign.
  • Watch out for common signs and symptoms to help you decide if you suspect your dog has cancer. For a full diagnosis, contact your veterinarian.
  • Dogs older than 10 years and certain dog breeds are especially susceptible to canine cancers.

Most Common Cancers in Dogs

Cancer is quite a common disease among dogs. Even so, some cancers are more prevalent than others. Let’s look at some of them.

cancer in dogs Insidence rate of certain cancers in dogs
Some common cancers in dogs include bone cancer, soft tissue sarcoma, and mast cell tumor
Source: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3658424/#:~:text=Canine%20cutaneous%20histiocytoma%20was%20the,Figure%201%2C%20%5B12%5D).

Bone Cancer (Canine Osteosarcoma)

Canine Osteosarcoma is a common type of bone cancer in dogs. In the US, veterinary doctors diagnose nearly 10,000 cases of canine bone cancer every year [1]

Osteosarcoma is excruciating and can cause swelling, loss of appetite and lethargy. Bone cancer in dogs has a high metastasis.

Bigger and heavier breeds like Boxers, Mastiffs and Golden Retrievers are most susceptible to bone marrow cancer, as well as other types of bone cancer.

Skin Cancer

Squamous cell carcinoma is another common form of skin cancer in dogs. Genetics affect your dog’s susceptibility but excess exposure to sunlight and chemicals can also cause skin carcinoma [2]

Luckily, you can easily spot mast cell tumors which cause sores and swelling underneath your dog’s skin.

Miniature and standard Schnauzers, Boston and Scottish Terriers, Boxers, and Poodles are susceptible to mast cell tumors.

Liver Cancer (Hepatocellular Carcinoma)

Hepatocellular Carcinoma (HCC) is a common type of liver cancer in dogs. HCC rarely occurs in canines, and most dogs with HCC are asymptomatic in the early stages. 

Therefore, tumors can be difficult to detect. Because HCC causes massive liver tumors, veterinary doctors can remove and treat them with relative ease [3].

Experts have noted no particular disposition to liver cancers among any breeds. However, breeds susceptible to metastatic forms of cancer are at a higher risk. An example is the Golden Retriever.

Bladder Cancer (Transitional Cell Carcinoma)

Less than 1% of all carcinoma diagnosis involves bladder cancer in dogs. Tumors attack the inside lining of the urinary bladder, sometimes metastasizing to the kidney, liver, prostate, vagina, lungs and lymph nodes [4].

Although any dog can get it, some breeds are more susceptible than others. The Shetland Sheepdogs, Scottish Terriers, Wirehair Fox Terriers and Beagles have a high risk of catching TCC.

cancer in dogs The risk of urothelial carcinoma (UC) in Scottish terriers with age
The risk for Scottish terriers at developing urothelial carcinoma increases significantly with age
Source: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6036476/

Spleen Cancer (Hemangiosarcoma)

Spleen cancer in dogs is common and often deadly. Hemangiosarcoma attacks the blood-rich areas of your pet’s body, which makes these tumors fatal [5].

A sudden tumor rupture causes massive blood loss, which can lead to sudden death. Once diagnosed, many veterinarians make drastic decisions to save these dogs’ lives.

German Shepherds, Golden Retrievers, Labrador Retrievers and Portuguese Water Dogs are the most susceptible breeds, with males at higher risks than females.

Breast Cancer (Mammary Carcinoma)

Mammary carcinoma is quite common among female dogs. Unspayed females or those spayed after two years of age are at a higher risk of contracting these tumors. 

However, these types of cancer aren’t fatal as they have a good prognosis following surgical resection [6].

Poodles, Dachshunds, and Spaniels have higher susceptibility than other breeds. Breast cancer in dogs is also prevalent due to obesity.

Stomach Cancer

Just like hemangiosarcoma, stomach cancer in dogs is rare but just as devastating. Your dog may not show symptoms until the tumor is at an advanced stage. 

Malignant tumors can spread to other parts of the body, leading to a higher risk of death. Ulcerating tumors can also cause your dog’s stomach to perforate, causing a serious condition called peritonitis [7].

Older males of nine years and above are susceptible to this disease. Rough Collies, Chow Chows and Staffordshire Bull Terrier breeds are also at the highest risk of this disease.

Lung Cancer

Lung cancer is relatively rare in dogs. It has no primary cause. Instead, tumors form in your dog’s lungs because of a metastatic spread of other cancers [8]. Dogs 10 years or older are most affected, regardless of their sex or breed.

Lung cancer in dogs can also spread to other organs, including the lining of its chest cavity, lung lobes, bones and brain.

Testicular Cancer

Although testicular cancer in dogs is prevalent, fewer dogs are affected by it since many males are neutered while young. Any tumor on normally descended testicles is often benign but tumors on retractile testicles can be malignant [9].

Older male dogs aged 10 years or more are at the highest risk of this disease, although young dogs catch these tumors just as easily.

Thyroid cancer

Thyroid cancer is also relatively rare among dogs, and almost half of all thyroid tumors are benign. However, when cancerous masses form in your dog’s thyroid area, they are usually malignant [10].

Older dogs are at a higher risk of thyroid cancer. Boxers, Golden Retrievers and Beagles are at a higher risk than other breeds.

Symptoms of Cancer in Dogs

Cancer symptoms in dogs may vary depending on the type of cancer involved [11]. However, some common signs and symptoms across all these types include:

  • Excessive thirst
  • Sudden loss of appetite
  • Sudden weight loss
  • Lethargy 
  • Abnormal odors and discharges from mouth, anus, ears or eyes
  • Depression


Here are some cancer questions many pet owners ask about their dogs:

Is My Dog at Risk for Cancer?

Yes, your dog is at risk. It is estimated that at least 25% of all dogs will develop cancer in their lives [12][13]

Also, one in two dogs aged above 10 years will develop cancer. Fortunately, many of these cancers are treatable if diagnosed early.

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

You may have suspicions about your dog’s tumors, but the best way to know is to visit your veterinarian. They can do a biopsy of the tumor and test the cells [11]. The results will help you and your vet make better decisions on the medical care for your dog.

How Long Can a Dog Live After Being Diagnosed With Cancer?

It entirely depends on the diagnosis of your dog. Some cancers are benign, and your dog can live many years even after diagnosis. Other forms of cancer are deadly, and they often come with terrible signs and symptoms [14]

When you notice certain symptoms like swollen lymph nodes, lethargy, loss of appetite, limping or abnormal body discharges, contact your veterinary doctor immediately. Once they conduct tests on your dog, they’ll give you an appropriate diagnosis and prognosis.

Is a Dog With Cancer in Pain? 

Your dog may be in pain, depending on the type of diagnosis your veterinarian gives [14]. Not all cancers are painful, and some dogs are more resilient than others in handling pain. However, watch out for atypical behavior as an indicator of pain. Some examples include:

cancer in dogs

  • Limping
  • Heavy panting
  • Excessive Aggression
  • Excessive self-grooming

What Are Treatment Options for Dogs With Cancer?

Your dog can be treated in four different ways:


Veterinary oncologists can perform surgery on your dog to remove all cancerous tissue. Surgery can be quite successful where tumors have not spread beyond their initial location [15]

If a tumor is caught early, surgery can be enough to cure the animal. Other times, surgery goes hand in hand with radiation or chemotherapy depending on the case.

Radiation Therapy

Radiation treatments work to deliver just enough radiation to destroy or injure cancerous cells, which prevents them from reproducing [15]. Also, radiation therapy prevents damage to healthy cells and tissue.


You can also use chemotherapy treatments to kill cancer cells in your dog’s body without destroying normal cells. They specifically target abnormal cells and tumors [15]. Your vet can administer chemotherapy drugs to your dog orally or using a fine needle injection.

Combination Therapy

Combination therapy uses two or more treatment options to fight against cancer at once [15]. As there is no single best treatment for all dog cancers and using combinations can maximize the benefits of each method to deliver effective treatment and save your dog’s life.


Dogs are affected by cancer just like human beings are. Early diagnosis and treatment can save your dog’s life. Set an appointment with a veterinarian regularly to ensure your dog is fully healthy.

If you own a susceptible dog breed, pay special attention to common symptoms like mouth discharges, unusual swelling and weight loss. Care and treatment are available and increases your dog’s lifespan.


  1. “Osteosarcoma – A Deadly Bone Tumor of Dogs.” Morris Animal Foundation, www.morrisanimalfoundation.org/article/osteosarcoma-deadly-bone-tumor-dogs.
  2. Erb, Hilarie. “Dog Skin Cancer: Types, Symptoms, and Treatment.” American Kennel Club, American Kennel Club, 20 May 2021, www.akc.org/expert-advice/health/dog-skin-cancer-types-symptoms-treatment/.
  3. Burke, Anna. “Liver Cancer in Dogs: Symptoms, Diagnosis, and Treatment.” American Kennel Club, American Kennel Club, 15 Oct. 2020, www.akc.org/expert-advice/health/liver-cancer-dogs-symptoms-diagnosis-treatment/.
  4. “Canine Bladder Cancer.” Long Island Veterinary Specialists, 5 June 2018, www.livs.org/canine-bladder-cancer/.
  5. “Hemangiosarcoma – A Heartbreaking Cancer That Strikes Without Warning.” Hemangiosarcoma in Dogs – A Deadly Cancer, www.morrisanimalfoundation.org/article/hemangiosarcoma-cancer-in-dogs.
  6. “Canine Mammary Tumors.” NC State Veterinary Medicine, 22 Nov. 2019, cvm.ncsu.edu/nc-state-vet-hospital/small-animal/oncology/canine-mammary-tumors/.
  7. “Gastric Cancer.” The National Canine Cancer Foundation, 10 Apr. 2021, wearethecure.org/learn-more-about-canine-cancer/canine-cancer-library/gastric-cancer/.
  8. “Lung Tumors in Dogs ” Small Animal Hospital ” College of Veterinary Medicine ” University of Florida.” University of Florida, smallanimal.vethospital.ufl.edu/clinical-services/oncology/types-of-cancer-and-treatment/lung-tumors-in-dogs/.
  9. Brister, Jacqueline. “Testicular Cancer in Dogs.” VIN, 18 Sept. 2019, veterinarypartner.vin.com/default.aspx?pid=19239&catId=102899&id=9284643.
  10. “Thyroid Tumor.” Animal Cancer and Imaging Center, www.veterinarycancer.com/thyroid-tumor.
  11. “Dog Cancer – Symptoms, Diagnosis & Treatment.” Countryside Veterinary Clinic, 12 June 2019, www.countrysideveterinaryclinic.org/services/dogs/dog-cancer.
  12. “Is My Dog at Risk for Cancer?” AAHA , www.aaha.org/your-pet/pet-owner-education/ask-aaha/canine-cancer/.
  13. “FAQs.” Veterinary Cancer Society, vetcancersociety.org/pet-owners/faqs/.
  14. “Cancer in Dogs: Symptoms and Treatment.” Blue Cross, www.bluecross.org.uk/pet-advice/coping-cancer-dogs.
  15. Cancer Treatment By Manuals Staff Last full review/revision May 2020 , et al. “Cancer Treatment – Special Pet Topics.” Veterinary Manual, MSD Veterinary Manual, www.msdvetmanual.com/special-pet-topics/cancer-and-tumors/cancer-treatment.