The essentials
- Many factors contribute to a dog’s chance of developing cancer — Some are easier to control than others.
- Different cancers cause different symptoms in dogs —There are a few common problems you can look out for. In most cases, earlier diagnosis leads to better outcomes.
- Take steps to reduce certain risk factors — Many of these are easy to do and may improve your dog’s quality of life in other ways.
Facing a cancer diagnosis for your beloved dog can be a heart-wrenching experience, but it’s a reality that many pet parents have to face. Cancer is a leading cause of death in dogs, especially as they age, and one in four dogs will develop cancer during their lifetime. Cancer is most common in older dogs, as well as certain breeds, but it can affect any dog. While it’s a word that no pet parent wants to hear, it is important to be aware of the causes, types, and symptoms of cancer in dogs.
In most cases, diagnosing and treating cancer as early as possible leads to a more favorable prognosis. While unfortunately there is no surefire way to prevent cancer, there are ways to help reduce your dog’s risk factors and promote a healthier lifestyle.
Causes of cancer in dogs
In order to consider ways we can help prevent cancer in our furry family members, it’s important to understand the possible causes. There is still much we don’t know about why cancer develops, but contributing factors include genetics, aging, environmental exposure, and more.
Genetics
Some dog breeds inherit genetic traits that make them more likely to develop cancer in general or develop a certain type of cancer. For instance, Scottish terriers are up to 20 times more likely to develop bladder cancer (transitional cell carcinoma) than other breeds. Poodles, golden retrievers, and several other breeds are more at risk for cancer of the lymph nodes (lymphoma). Boxers tend to be prone to several types of cancer, including lymphoma and mast cell tumors.
Researchers are learning to identify genetic markers for these cancers. Genetic markers help breeders work toward eliminating these inherited traits from their lines. This means we should see fewer incidences of inherited cancers in future generations.
Age
We all want our pets to live longer, and there have been many advances in veterinary medicine that have made this possible. However, as dog life expectancy increases, so does a dog’s risk of developing cancer during their lifetime. As individuals age, their cells undergo more divisions, increasing the chances of DNA damage and mutations that can lead to cancer. Additionally, the immune system tends to weaken with age, making it less effective at detecting and destroying cancer cells. Unfortunately, almost half of dogs over the age of 10 will develop cancer.
Environmental factors
A dog’s environment impacts their chances of developing cancer and what type. If someone in your household smokes, your dog is at an increased risk of tumors in the lungs and nose. Secondhand smoke isn’t the only environmental factor that affects your dog’s health. Exposure to certain pesticides and herbicides can raise a dog’s risk of cancer. Pups that spend a lot of time in the sun are also at an increased risk of developing certain skin cancers, especially those lighter in color.
Of course, certain environmental factors are outside of our control. Dogs, like humans, are susceptible to allergens and pollutants in the air and water. One study compared cancer rates in dogs living in areas with a history of illegal waste dumping. It found a connection between the dogs’ proximity to these areas and an increased risk of cancer, specifically lymphoma.
Hormones
Sex hormones can play a role in the development of cancer as well. For this reason, there are conflicting opinions in the veterinary field about the best time to spay and neuter your dog.
Sterilization surgeries (spaying and neutering) involve removing the sex organs to prevent unwanted litters, future health issues, and problem behaviors. Among other benefits, they also eliminate the possibility of uterine and ovarian cancer in female dogs. Neutering eliminates the risk of testicular cancer in male dogs, although may be associated with an increased risk of prostate cancer.
Studies show that female dogs who begin their heat cycle prior to being spayed are at an increased risk of developing mammary cancer. However, spaying or neutering early in life may be associated with an increased risk of joint issues and other types of cancers, such as osteosarcoma (bone cancer), hemangiosarcoma, lymphoma, and mast cell tumors. As many of the studies involving this correlation were small and did not take into account breed-related risk factors, this area is still being investigated and more research is needed.
Spaying and neutering is still recommended by vets. If you have questions or concerns about the best time to spay or neuter your dog, they will be happy to discuss it with you.
Body condition
The risk of cancer also increases with canine obesity. Obesity can predispose dogs to developing certain types of cancer, which may be related to factors such as insulin resistance, hormonal imbalance, and chronic inflammation.
Viruses
Certain viruses increase a dog’s risk of developing cancer. A trip to the dog park or a busy boarding facility may find Fido catching the contagious papillomavirus, which can lead to oral warts. Luckily, these masses are mostly benign and often resolve on their own.
Other
Some cancers, such as canine transmissible venereal tumors, are transmitted during mating. Additionally, areas of the body with chronic inflammation or sites of serious traumatic injuries may be more likely to develop cancer.
Common types and symptoms of cancer in dogs
Cancer can affect any part of a dog’s body, including the bones, blood, skin, and organs. There are many different types of cancer that affect our furry family members, including lymphoma, mast cell tumors, melanoma, osteosarcoma, hemangiosarcoma, and mammary carcinoma. As such, the symptoms can vary widely. Though every cancer presents differently, there are some common warning signs to watch for, including:
- Abnormal lumps and bumps, especially those that appear suddenly or grow at a rapid pace
- Sores that don’t heal
- Weight loss
- Loss of appetite or difficulty eating
- Bleeding or discharge from any opening on the body
- Diarrhea or vomiting
- Difficulty breathing or coughing
- Difficulty walking, including limping and/or stiffness;
- Changes in urination or defecation
- Foul odors or bad breath
- Lethargy or weakness
- Loss of interest in exercise or play
- Neurological signs such as seizures, disorientation, or loss of balance
- Changes in behavior
None of these symptoms on their own are a definitive sign of cancer. In fact, many other less serious medical conditions can and do cause similar signs. It’s also possible for early signs of cancer to be subtle and easily missed. Some cancers may only cause obvious signs once they are more advanced.
Not all tumors are cancerous. Some are benign, meaning they are not harmful and do not spread. However, malignant tumors can invade and damage nearby tissues and spread to other parts of the body through a process called metastasis.
Because of this, it’s always best to keep up with your dog’s regular vet visits to get an expert opinion about anything that concerns you. Early detection and treatment significantly improve the chances of successful treatment.
How vets diagnose and treat cancer
Diagnosing cancer in dogs begins with a thorough medical history and nose-to-tail examination, where your veterinarian will feel for lumps and bumps, check lymph nodes, and assess your dog’s overall health.
If your vet finds a tumor, cytology (using a needle to remove a small sample of cells) or biopsy (removing all or part of a tumor) for evaluation is needed to confirm if it’s cancerous and determine the type and severity. Your vet may also recommend tests like bloodwork, X-rays, or ultrasounds to rule out other medical conditions, look for signs of cancer, and determine if it has spread (a process known as staging). In some cases, your vet may recommend more specialized imaging like CT scans or MRIs, or referral to a veterinary oncologist.
Treatment options for canine cancer vary depending on the type and stage of cancer and the dog’s overall health. Common treatment approaches include surgery to remove tumors, chemotherapy, radiation, cryosurgery (freezing), hyperthermia (heating), and immunotherapy. In some cases, hospice or palliative care may be recommended to manage pain and improve a dog’s quality of life when a cure is not possible.
How to decrease your dog’s risk of cancer
Unfortunately in many cases, it is not possible to prevent your dog from developing cancer. But there are steps you can take to help reduce certain risk factors, and they might begin before you even become a pet parent.
Breeder selection
Sometimes the best way to fight canine cancer is to consider a puppy’s health before you ever add one to your family. Selecting a reputable breeder is an important step in this process.
Look for a breeder with a good word-of-mouth reputation among dog owners, a strong working relationship with a vet, and extensive knowledge of their chosen breed. A reputable breeder should welcome your questions about health conditions and temperament and allow you to visit their breeding facilities. They will perform health testing to screen their breeding dogs for common cancers and medical conditions associated with their breed. The American Kennel Club is a good place to start your search.
Adopting a dog is a wonderful and worthwhile endeavor. While there may be unknowns regarding breeding and medical history, don’t let it discourage you from adding a pet in need to your family. You can still be proactive in providing them with a healthy lifestyle and exceptional care (and you can even DNA test them).
Spaying and neutering
During your puppy’s first appointments, speak to your vet about when they recommend spaying or neutering your new pet. Your vet should consider your dog’s breed, age, and health. You may also wish to spay or neuter an older adopted dog to prevent future health complications.
Proper nutrition and body condition
Though no one food or supplement can prevent cancer, proper nutrition is key to boosting your pet’s health and immune system. Feed your dog a WSAVA-compliant complete and balanced diet based on their life stage. Keep an eye on portion size, frequency of meals, and nutritional value of the food, and provide opportunities for daily exercise. Obesity significantly shortens a dog’s life span by making them susceptible to several health conditions, including cancer.
Reduced exposure to harmful substances
Of course, we all want to keep harmful substances away from our pets. But reducing cancer risk is another reason to be extra cautious about your dog’s exposure to cigarette smoke, herbicides, pesticides, and caustic household cleaners. Always read the labels, and choose gentler or natural formulas free of known carcinogens. It’s also important to avoid excessive sun exposure, for example by keeping your dog indoors during the hottest part of the day and using pet-safe sunscreen if indicated.
Conduct at-home checks and keep up to date with veterinary care
While petting or grooming your dog, run your hands over their body and alert your vet to any new lumps or bumps. Additionally, be alert to any changes in your dog’s appetite, thirst, weight, energy level, urination, and defecation. Catching cancer early can increase your dog’s chances of a full recovery.
While following these measures can help reduce your dog’s risk factors for developing cancer, it’s important to remember that, unfortunately, cancer is not always preventable. Genetics, environmental factors, and age still play a role, even with the best of care. However, by making healthy choices and prioritizing your dog’s well-being, you can maximize their chances of a long, happy, and healthy life.
Frequently asked questions
What foods cause cancer in dogs?
No individual foods have been identified as cancer-causing in dogs. Mycotoxins, toxic substances produced by certain molds that can grow on food crops, can be associated with an increased risk of cancer. However, this risk is low for most commercial dog foods.
Does stress cause cancer in dogs?
Research suggests a potential link between chronic stress and the development of cancer. The medical community continues to explore whether stress causes cancer in humans. Hopefully, as our knowledge of canine cancer develops, we can learn more about how it’s linked to stress.
What is the most aggressive cancer in dogs?
Hemangiosarcoma is often considered the most aggressive cancer in dogs due to its rapid growth, sudden onset, and poor prognosis. This cancer originates in the cells lining blood vessels and can quickly spread throughout the body, most commonly affecting the spleen and heart. Early detection is difficult as symptoms often don’t appear until the cancer is advanced, and even with aggressive treatment, the prognosis is generally poor.
Is there a way to prevent cancer in dogs?
As the cause is often unknown or involves multiple factors, cancer is difficult to prevent. Choosing a reputable breeder and making healthy lifestyle choices can be beneficial. Spaying before 12 months of age and neutering your dog can reduce the risk of mammary cancer and prevent testicular cancer. You should also avoid exposure to carcinogens, such as secondhand smoke. Keeping up with routine veterinary care is the best thing you can do for your dog’s health.
Can dogs get cancer from not being bathed enough?
Bathing your dog too often can lead to dry skin, while not bathing often enough can lead to a smelly dog and the potential for skin irritation, infection, or inflammation. Luckily, cancer is not associated with how often you bathe your dog.
