Table of Contents
- What Is Cancer in Dogs?
- How Do Dogs Get Cancer?
- Signs and Symptoms of Cancer in Dogs
- When to Seek Help from a Vet
- Can You Prevent Cancer in Dogs?
- FAQs Related to How Dogs Get Cancer
- How Do Dogs Get Cancer: Before You Go…
Cancer is a frightening word, and as a dog owner, it's natural to worry about your furry friend's health.
Just like in humans, cancer in dogs is complex, with multiple factors contributing to its development.
But how do dogs get cancer, and what can you do to reduce the risks?
Let's explore the science behind canine cancer, its causes, symptoms, and ways to protect your pup.
What Is Cancer in Dogs?
The National Cancer Institute defines cancer as the uncontrolled growth of abnormal cells that can form tumors and spread to different parts of the body.
Some cancers remain localized, meaning they stay confined to one area and do not spread to other body parts.
These cancers are often easier to treat and may be surgically removed.
Others metastasize, spreading to other organs or tissues through the bloodstream or lymphatic system.
This makes treatment more complex and reduces the chances of a full recovery.
Common Types of Cancer in Dogs
Dogs, like humans, can be more susceptible to certain types of cancers due to their genetics, environment, and overall health.
Some breeds are predisposed to specific cancers, while external factors such as diet, exposure to toxins, and sun exposure can contribute to their development.
Here are some of the most common types of cancer seen in dogs:
- Lymphoma – Affects the lymph nodes and immune system.
- Osteosarcoma – A highly aggressive form of bone cancer.
- Mast Cell Tumors – Common skin tumors that can be benign or malignant.
- Hemangiosarcoma – A fast-spreading cancer affecting the blood vessels.
- Melanoma – Typically found in the mouth, skin, or nail beds.
Each type of cancer presents different symptoms, but understanding the causes can help you take preventive steps!
We have discussed each cancer in detail; click on each to read the full article!
How Do Dogs Get Cancer?
All that said, how does a dog get cancer? In truth, there is no single cause of cancer in dogs.
Instead, it develops due to one or a combination of genetic, environmental, and lifestyle factors.
1. Genetics and Breed Predisposition
Certain dog breeds are more prone to cancer due to inherited genetic factors.
Over generations, some breeds have developed genetic mutations that increase their susceptibility to specific types of cancer.
This happens because purebred dogs have a smaller gene pool, making it more likely for genetic conditions to pass down from parents to offspring.
For example:
- Golden Retrievers – High risk of lymphoma and hemangiosarcoma due to genetic mutations that affect the immune system and blood vessel integrity.
- Boxers – They are susceptible to mast cell tumors, which may be linked to an inherited defect in their immune response.
- Bernese Mountain Dogs – Higher incidence of histiocytic sarcoma, a rare but aggressive form of cancer believed to be linked to breed-specific genetic markers.
- Rottweilers – More likely to develop bone cancer (osteosarcoma), possibly due to rapid growth rates and inherited bone density traits.
While you can't change genetics, knowing breed risks allows for early screening and proactive care.
RELATED: Why Dogs with Cancer Smell Bad
2. Environmental Factors
Your dog's surroundings can significantly impact their cancer risk.
Over time, exposure to certain chemicals and pollutants can lead to DNA damage, cellular mutations, and chronic inflammation, all of which can contribute to cancer development.
Some known carcinogens include:
Pesticides and Herbicides
Many chemical lawn treatments contain carcinogens that dogs can absorb through their paws or ingest when licking their fur.
Studies have linked certain herbicides, like 2,4-D, to an increased risk of bladder cancer in dogs.
Secondhand Smoke
Dogs exposed to tobacco smoke have a higher likelihood of developing lung cancer and nasal tumors, especially those with long snouts, as their nasal passages trap more toxins.
Air Pollution
Living in industrial areas or places with high vehicle emissions may expose dogs to airborne pollutants, increasing their risk of respiratory cancers.
UV Radiation
Light-colored or short-haired dogs, such as Dalmatians and Bull Terriers, are more prone to squamous cell carcinoma, a form of skin cancer caused by excessive sun exposure.
Reducing exposure to these risks, such as using pet-safe lawn care products, limiting sun and secondhand smoke exposure, and keeping indoor air clean, can help.
RELATED: 10 Environmental Causes of Cancer in Dogs
3. Diet and Nutrition
What your dog eats plays a crucial role in its overall health.
Diet impacts inflammation, immune function, and cell growth, influencing cancer risk.
Certain dietary factors can contribute to cancer, including:
Highly processed foods
Many commercial dog foods contain artificial preservatives, fillers, and low-quality ingredients that may not provide optimal nutrition.
High-carb diets
Excessive carbohydrates can lead to obesity and chronic inflammation, increasing the risk of cancer.
Toxic foods
Some human foods, such as artificial sweeteners and processed meats, may contain carcinogens that can damage cells over time.
A balanced, high-quality diet rich in proteins, antioxidants, and omega-3 fatty acids can help reduce inflammation and support immune health.
RELATED: 10 Cancer Causing Ingredients in Dog Foods
4. Age and Hormonal Factors
Cancer is more common in senior dogs, as cellular damage accumulates over time.
As a dog ages, their body undergoes changes that make them more vulnerable to diseases, including cancer.
Cells divide and regenerate less efficiently, and the immune system becomes weaker, making it harder to fight off abnormal cell growth.
Additionally, hormones play a crucial role in cell regulation, and when hormone levels fluctuate or remain unregulated, they can contribute to cancer development.
Some of the most common hormone-related cancers in dogs include:
Mammary Tumors in Unspayed Females
Female dogs that are not spayed have a significantly higher risk of developing mammary gland tumors (breast cancer).
Studies show that dogs spayed before their first heat cycle have less than a 1% chance of developing mammary cancer, whereas those spayed after multiple heat cycles have an increased risk of up to 26%.
Testicular Cancer in Unneutered Males
Male dogs that are not neutered are more prone to developing testicular cancer, particularly as they age.
Neutering can completely eliminate this risk.
Prostate Cancer
While rare in dogs, prostate cancer is more likely to occur in older, unneutered males.
Unlike testicular cancer, neutering does not prevent prostate cancer, but it may reduce certain risk factors.
Osteosarcoma and Growth Hormones
Large and giant breeds that experience rapid growth in their early years may be at a higher risk of developing osteosarcoma.
Growth hormones and rapid bone development are thought to contribute to this aggressive cancer.
Spaying and neutering at an appropriate age can reduce hormonal-driven cancers in dogs.
5. Weakened Immune System
A strong immune system plays a crucial role in detecting and eliminating abnormal cells before they can develop into tumors.
However, when the immune system is compromised, the body has a harder time fighting off infections, regulating inflammation, and stopping the growth of cancerous cells.
Factors that can weaken immunity include:
- Chronic illnesses or infections.
- Long-term steroid or antibiotic use.
- Poor diet and malnutrition.
- Chronic stress and lack of exercise.
Boosting immunity through regular exercise, a balanced diet, and vet check-ups can improve your dog's ability to stay healthy.
RELATED: How To Boost Your Dog's Immune System
Signs and Symptoms of Cancer in Dogs
Early detection is key in managing cancer. Some warning signs include:
- Unexplained lumps or swelling.
- Sudden weight loss or loss of appetite.
- Lethargy or lack of energy.
- Persistent coughing or difficulty breathing.
- Wounds that won't heal.
- Changes in bathroom habits (blood in urine or stool).
- Foul-smelling breath or bleeding from the mouth
- Lameness or swelling in the limbs
- Neurological symptoms (seizures, head tilting, or incoordination)
If you notice any of these symptoms, schedule a vet visit immediately.
When to Seek Help from a Vet
Not all lumps or symptoms indicate cancer, but early detection increases treatment success.
Seek veterinary care immediately if:
- A lump grows rapidly, changes in texture, or starts bleeding.
- Your dog experiences chronic vomiting, diarrhea, or rapid weight loss.
- There is difficulty breathing, persistent coughing, or unusual bleeding.
- Your dog shows unexplained lethargy, sudden behavioral changes, or frequent collapsing.
- You notice pain or difficulty moving, especially in large or senior dogs.
Your vet may recommend biopsies, X-rays, ultrasounds, or blood tests to diagnose potential cancer.
Some cases may require advanced imaging, such as MRIs or CT scans for deeper analysis.
Early diagnosis greatly improves treatment success, whether through surgery, chemotherapy, radiation, or palliative care, to enhance your dog's quality of life.
RELATED: What To Do If You Can't Afford Your Dog's Cancer Treatment
Can You Prevent Cancer in Dogs?
While cancer isn't always preventable, these strategies may reduce the risk:
- Routine vet check-ups – Annual screenings help detect cancer early.
- Healthy diet – Opt for natural, high-quality dog food with antioxidants and incorporate fresh, whole foods as much as possible.
- Reduce environmental risks – Use pet-safe lawn and home products, avoid tobacco smoke, toxic chemicals, and excessive sun exposure, and use air purifiers to keep your indoor air clean.
- Spaying and neutering – These procedures can lower the risk of certain hormone-related cancers, plus many more benefits.
- Exercise and weight management – Obesity is linked to inflammation and cancer, so make sure to monitor and manage your dog's weight.
RELATED: TOP #113: Dangers of Dog Obesity and How to Slim Them Down
FAQs Related to How Dogs Get Cancer
How long do dogs with cancer live?
Lifespan varies depending on cancer type, stage, and treatment.
Some dogs live for months to years with proper treatment, while aggressive cancers may shorten their lifespan significantly.
What dog breeds are most prone to cancer?
Breeds like Golden Retrievers, Boxers, Bernese Mountain Dogs, and Rottweilers have higher cancer rates.
Genetics plays a role, so early screening is recommended.
Can cancer in dogs be treated?
Yes! Treatment options include surgery, chemotherapy, radiation, and holistic therapies.
The success rate depends on the cancer type and how early it's detected.
RELATED: Should I Treat My Dog for Cancer?
How Do Dogs Get Cancer: Before You Go…
Understanding how dogs get cancer allows you to take proactive steps toward prevention and early detection.
While some factors, like genetics and aging, are beyond control, diet, environment, and veterinary care are crucial in reducing risks.
If you suspect your dog has cancer, don't wait—schedule a vet visit.
Early detection can make all the difference in treatment success!
To learn more about dogs and cancer, check out our list of articles linked below!
