November has been designated National Pet Cancer Awareness Month. While most people know that cancer is a leading cause of death in humans, many do not realize that it is also a leading cause of death among pets, especially older dogs and cats. Like their human companions, animals can develop different types of cancers. Fortunately, many cancers can be treated, especially when detected early. The goal of National Pet Cancer Awareness Month is to educate the public about the most common cancers in pets and to teach pet parents how to recognize the signs and symptoms of cancer.
What is cancer exactly?
Cancer is a genetic change in a cell that causes it to divide and proliferate uncontrollably. There are two types of cancer: benign and malignant. Benign tumors grow but do not invade tissue and do not spread to distant locations. Malignant tumors grow invasively and can metastasize (spread throughout the body).
How common is cancer in dogs?
Unfortunately, cancer is one of the leading causes of death in older animals. According to the American Veterinary Medical Association (AVMA) 1 in every 4 dogs will develop cancer in their lifetime. The Veterinary Cancer Society estimates that almost half of all dogs over ten will develop cancer.
How do you know if your dog has cancer?
Cancer encompasses a variety of diseases in which cells proliferate abnormally. Depending on the type of cancer and location, the specific presenting symptoms, prognosis, and treatment will vary. However, although each cancer is unique, they share many signs and symptoms. To increase your odds of detecting cancer in your pets early, you should become familiar with the common signs and symptoms of cancer. Be alert and watch for any changes in your pet. Some of the things to watch for are unexplained weight loss, trouble eating, decreased activity level, coughing, breathing problems, abnormal bleeding, lameness or limping, and the appearance of any skin growths or lumps and bumps. It is important to realize that these are only some of the most common signs and symptoms of cancer. These signs and symptoms are not specific to cancer and may be seen in other diseases. The key is to be observant and notify your veterinarian immediately if you notice any of these symptoms or have other health concerns about your dog.
Common signs and symptoms of cancer in pets:
- Abnormal swelling
- Sores that do not heal
- Weight loss
- Difficulty breathing
- Bleeding or discharge from the mouth, nose or other body openings
- Lumps, bumps, masses or discolored skin
- Difficulty eating, swallowing or loss of appetite
- Abnormal odor
- Unexplained lameness, pain or swelling
- Persistent diarrhea or vomiting
*Note this list is not comprehensive. There may be other signs of cancer and these signs may also be seen with other diseases.
The importance of regular veterinary visits
Unfortunately, no matter how vigilant we are, our pets may be asymptomatic in the early stages of cancer. To improve the chances of early detection, you should take your pet in for check-ups regularly. Your veterinarian will do a complete examination checking your pet from head to tail, looking for abnormal skin growths (lumps and bumps), enlarged organs or masses in your pet’s abdomen (belly), abnormal heart or lung sounds, and abnormalities in their eyes, ears, and mouth. These exams are important because veterinarians often discover things that you may not have noticed. For instance, how often do you open your pet’s mouth and look inside? Sadly, most people don’t do this, and oral cancers are common in pets. When oral cancers become symptomatic and animals stop eating or drool excessively, it may be too late because the tumor is too big to treat. Remember the goal and the best way to improve your pets’ odds of beating cancer is early detection. Regular examinations are one of the best ways to do this. Personally, I recommend animals over 6 years of age be seen by their veterinarian seen twice a year.
Screening tests for cancer
Not all cancers can be detected on physical examinations alone, so your veterinarian may also recommend screening tests like blood work, urinalysis, and radiographs (x-rays), to uncover underlying diseases like cancer. These tests are quick and painless and can give your veterinarian a lot of information about your pet’s health. The specific tests ordered by your veterinarian will be individualized and depend on the age, sex, and breed of your pet.
How is cancer diagnosed in pets?
If your veterinarian is concerned about a lump or bump, they will likely recommend a fine needle aspirate or biopsy to determine if the lesion is benign or malignant. Fine needle aspirates and biopsies are often recommended prior to surgery because they help your veterinarian determine if the mass must be removed at all and if it does, how aggressive the surgery needs to be to decrease the odds of it recurring in the same area. For pets suspected of having cancer but without visible masses your veterinarian may recommend one or more of the following diagnostic tests: radiographs (x-rays), blood tests, an ultrasound, and possibly advanced imaging such as a CT scan, MRI or PET scan.
What are the most common cancers seen in dogs?
Like their human companions, dogs can develop many different types of cancer. According to the Veterinary Cancer Society, the most common cancers seen in dogs are mammary tumors. Other common types of cancers seen in dogs are: lymphoma, osteosarcomas, mast cell tumors, oral melanomas, hemangiosarcomas, and transitional cell carcinomas.
What should you do if your dog is diagnosed with cancer?
Once you overcome the initial shock, it is important to realize that all cancers are different, and some are more treatable than others. The decision to treat and how aggressively to treat can be complicated. It depends on the cancer’s location, its stage, and the patient’s general health. Your veterinarian may suggest you see a veterinary oncologist to sort through the latest treatment options and determine which treatment is best for your pet.
What are the treatment options for cancer in dogs?
The treatment depends on the type of cancer and location. Treatment may include surgery, chemotherapy, radiation and immunotherapy, or a combination of these treatments. As is the case with other diseases, typically the earlier cancer is detected the better the prognosis. In recent years, our ability to treat cancer has improved dramatically and pets with cancer are living longer. Fortunately, recent advances in veterinary oncology have made many previously untreatable cancers now treatable.
Is cancer treatment in pets painful and will they lose their hair?
While remission is the ultimate goal, quality of life is equally important. As a result, cancer treatments in dogs are generally less aggressive than regimens used in people. Therefore, pets typically do not suffer from some of the troubling side effects seen in people, such as nausea, vomiting, hair loss, and extreme fatigue. If side effects occur, your veterinarian will adjust the treatment to ensure that your pet remains as comfortable as possible. The goal is to prolong your pet’s life while still maintaining quality of life.
Are some cancers more treatable than others?
Yes, all cancers are different, and some are more treatable than others. The type of cancer, location, size, and response to treatment all affect the ultimate prognosis. With many cancers, the earlier treatment is started the better the prognosis and ultimately the longer the survival times. That's why it is so important to bring your pet to their veterinarian for examinations at least once a year.
Are there clinical trials for dogs?
Yes! While recent advances in the field of veterinary oncology have enabled veterinarians to treat many previously untreatable cancers, there is still a pressing need for more safe and effective treatments. Clinical trials are an important step in the development of new treatment protocols. They enable researchers to evaluate new medications by studying how medications are metabolized, establishing effective doses, and identifying any potential side effects. There are hundreds of clinical trials being conducted at universities and veterinary specialty clinics around the United States. If your dog has an untreatable cancer, or if the treatment is cost-prohibitive, consider enrolling your dog in a clinical trial since most are partially or wholly subsidized. Besides helping your pet, you may be helping countless other animals in the fight against cancer.
The AVMA”s website has information about clinical trials and a searchable database for ongoing clinical trials. I also recommend pet owners ask their veterinarian or veterinary oncologist if they are familiar with any local trials that may be of benefit to their pet.
Can cancer recur in dogs?
Unfortunately, just like in humans, some cancers can recur. The likelihood of recurrence depends on the type of cancer. Before treatment your veterinarian or veterinary oncologist will give you the latest statistics pertinent to your dog’s cancer type and stage. This will include median survival times with and without treatment, rates of remission, and odds of recurrence. These statistics, while not an exact guarantee, may help you make an informed decision that is right for you and your pet.
Is there anything you can do to prevent cancer in dogs?
You may be surprised to learn that some cancers are preventable. So how can you prevent cancer in your dog? Spaying your female dog before their first heat decreases their risk of mammary carcinoma. Neutering your male dog will prevent them from developing testicular cancer. A 10-year study by the University of California Davis found that the age when this should be done in male dogs depends on the breed. To learn more about this speak with your veterinarian or check out the study by the University of California Davis. If you have a hairless breed of dog or light-colored dogs (like Pit Bulls, Bull Terriers), they have a higher risk of developing sun-induced squamous cell carcinomas, especially if they spend a lot of time outdoors. If your dog is at risk for skin cancer, consider using pet-safe sunscreen on the hairless area or nonpigmented skin (belly and ears).
Are some dog breeds more prone to cancer?
Yes. Sadly, certain breeds have a genetic predisposition to certain cancers. Some of the breeds that are more likely to develop cancer are: Boxers, Golden Retrievers, Bernese Mountain Dogs, German Shepherds, and Rottweilers. However, it is important to know that any breed or mixed breed can develop cancer. If you have a dog breed that is predisposed to cancer it is important to be extra vigilant and notify your veterinarian right away if you notice any changes in your pet’s appearance or behavior.
Do pets with cancer need to be on a special diet?
No. If your pet is on a well-balanced diet and they are eating and maintaining their weight, there is no need to change their diet. The nutrition service at Tufts Veterinary School caution against feeding raw diets or raw treats (even freeze-dried raw foods) to pets with cancer. Raw meat, dairy and eggs have a high risk of bacterial contamination with: Salmonella, Listeria, E-coli, Campylobacter and more. Pets with cancer are at a greater risk for infection, especially pets undergoing chemotherapy.
Are there any online support groups for pet parents?
Yes. To find a support group in your area, speak with your veterinarian. The Animal Cancer Foundation (www.acfoundation.org) provides helpful articles about cancer in pets and pet loss support.
Take Away
Remember early detection and treatment is the best way to improve your pet’s odds of beating cancer. So make sure your pet gets regular check-ups, take advantage of recommended screening tests, and be familiar and on the lookout for the most common signs and symptoms of cancer in pets. Be sure to report any “lumps and bumps” or other abnormal findings to your veterinarian right away.
