Puppy Up Foundation | April Is National Cancer Control Month

dog and cat

The purpose of National Cancer Control Month is to raise awareness about cancer.

That’s also one of our three guiding missions of The Puppy Up Foundation.

How common is cancer in dogs?

Unfortunately, cancer is one of the leading causes of death in older animals. According to the Animal Cancer Foundation (ACF), 1 out of every 4 dogs and 1 out of every 5 cats will develop cancer in their lifetimes, and each year, approximately 6 million dogs and almost that many cats are diagnosed with cancer.

Cancer in pets can be found in the skin, bones, breast, head and neck, lymph system, abdomen and testicles. Leukemia is the most common type of cancer in cats and lymphoma and mammary gland cancers are the most common types of cancers in dogs.

What is Cancer?

Cancer is not just one disease; it is a group of diseases that can appear almost anywhere in the human or animal body. How it develops and its symptoms, diagnosis, and treatment vary widely based on the cancer type and where it is located in the body.

Cancer refers to cells growing out of control. There are over 100 types of cancers, but they all start with cells that begin to divide without stopping, and have the potential to spread to surrounding tissues or organs.

There is an important distinction we must make. Cancer is malignant growth, meaning cancer has the potential to spread (metastasize) to other parts of the body. This often occurs when cancer cells migrate from their primary or original site to nearby lymph nodes. Cancer cells can circulate throughout the body in blood or lymph vessels, and even a very small number of cells can produce new tumors. Cancer is classified according to its original location.

Benign growths do not spread to other parts of the body. There may be many benign growths, (fatty tumors, for example), but they are not outgrowths of one another. Benign growths don’t metastasize to other tissues or organs.

Dogs are affected by more forms of cancer compared to other companion animals. According to The Veterinary Cancer Society, cancer is the leading cause of death in 47% of dogs, especially dogs over age ten, and 32% of cats. Dogs get cancer at about the same rate as humans, while cats get fewer cancers. Some breeds or families of dogs have a higher incidence for developing cancer at an earlier age (see below), but in most cases it’s currently a disease found in aging animals.

What causes cancer?

Cells normally grow, divide and die in an orderly cycle as the body replaces worn out cells with new ones. When this cycle is disrupted, cells can develop abnormally, multiply out of control or fail to die on schedule. Cancer cells can often hide from or disable the immune system so it cannot find and eliminate them.

Cancer occurs when the genes that control the cell life cycle are altered. These include genes that promote cell growth (proto-oncogenes), those that turn off cell division (tumor suppressor genes), and genes that play a role in repairing damaged DNA. Cancer occurs when the body’s immune system cannot stop cells from replicating at an abnormally fast, disorderly pace.

Similar to humans, our pets are living longer due to advances in medicine and an emphasis on preventive care and nutrition. Living longer lives exposes our animals to diseases of aging, especially cancer. In many of these animals, the malignancy will look and behave much as it would in humans, i.e., spreading to the same organs in our companion animals as it does in people.

It is important to remember that, just as in humans, companion animal cancer is not caused by any single factor. While genetics and environmental factors can play roles in cancer’s development, other variables such as toxins, radiation, and tumor viruses, as well as hormones, can also be responsible for causing several types of cancer. And finally, suppressed or deficient immune systems can increase an animal’s risk of developing cancer.

Symptoms of Cancer

Early warning signs of cancer:

• Abnormal swelling
• A sore that does not heal
• Weight loss
• Loss of appetite
• Bleeding or discharge from any opening on the body
• Unpleasant or unusual odor
• Difficulty eating or swallowing
• Loss of energy
• Ongoing lameness or stiffness
• Difficulty breathing, urinating, or defecating

The 6 Most Common Types of Cancers in Dogs

There are two main forms of cancer in dogs: carcinomas and sarcomas. Carcinomas are growths made up of cells. These cells then multiply and cause the cancer to spread. Sarcomas are tumors that come from connective tissue. Its name generally comes from the area where the cancer originated.

Below are six of the most common types of cancers found in dogs, as well as the symptoms. Being educated about canine cancers and their symptoms will better help you identify a serious illness in your dog.

1. Hemangiosarcoma

This cancer begins in a dog’s blood cells. The most common organs affected are the spleen, skin, liver and heart, although it can be found in almost any part of the body. A tumor that has ruptured will be the cause of severe symptoms in your dog. If the tumor has ruptured near a vital organ, anemia and weakness will occur. The tumor is composed of blood, so a ruptured tumor will result in blood loss and the resulting anemia and weakness. You may be able to detect a tumor before it ruptures by feeling it under the skin or swelling on the bone. The most common breeds affected by hemangiosarcoma are German shepherds, Golden retrievers, Skye terriers, Portuguese Water Dogs and other large breeds.

2. Lymphosarcoma

Lymphosarcoma (or lymphoma for short) affects a dog’s immune system. The lymphoid tissues are found in many parts of the body often resulting in metastases. The main symptom is irregularly swollen lymph nodes which can be found in the upper and lower neck, behind the front legs, in front of and behind the back legs.

3. Osteosarcoma

The prefix osteo refers to the bone which is where osteosarcoma originates. Large breeds are highly at risk for osteosarcoma, therefore, owners of these breeds should be aware of the symptoms for early detection. Symptoms include pain, swelling, lack of physical activity and, in severe cases, trouble breathing. Osteosarcoma in its late stages usually spreads to the lungs making breathing and treatment difficult.

4. Mammary Carcinoma

Over half of all cancerous tumors in female dogs are mammary tumors, which makes breast cancer the most common type for females dogs. This type of cancer is highest in non-spayed female dogs. It is so common that approximately 25% of all non-spayed female canines will develop mammary carcinoma. While any tumor can be frightening, in over half the cases of mammary carcinoma removing the tumor through surgery is curative.

To put this in perspective, breast cancer is three times more common in dogs than in people. Female dogs are more likely to suffer from breast cancer if they were never spayed or were spayed after their first heat cycle, if they eat diets high in meat, and if they are overweight and more than a year old. It also seems to be more common in German shepherds, pointers, English springer spaniels, and miniature and toy poodles.

5. Melanoma

Melanoma can occur in any dog but is most commonly found in dark-skinned canines. It can reveal itself in dark, small lumps or as large wrinkled areas on the skin. Melanoma can be benign or malignant. Benign cases can result in a mass that is not harmful but can be uncomfortable and require removal. Malignant melanoma is incurable. By the time it is detected, it is often too late because it has spread throughout the body making surgery difficult if not impossible. Radiation treatment can extend the life of the dog but will reduce his quality of life greatly. Chemotherapy is not effective in treating melanoma cases.

6. Mast cell tumors

Mast cell tumors are an extremely common form of cancer in older dogs and mixed breeds, as well as boxers, Boston terriers, Labrador retrievers, beagles, and schnauzers. Mast cells are found in the skin and other tissues, like the intestines or respiratory tract. They contain large amounts of histamines and enzymes that protect the body, but when tumors develop, that protection turns against the immune system. The first sign of a mast cell tumor is usually a lesion on the skin. Some mast cell tumors can also be uncomfortable and cause agitation.

10 Dog Breeds That Are Most Prone To Cancer
Bernese Mountain Dog
Boxer
Cocker Spaniel
Doberman Pinscher
German Shepherd Dog
Giant Schnauzer
Golden Retriever
Great Dane
Rottweiler
Standard Poodle

Are there diagnostic tests or exams that should be done regularly to try to detect cancer in dogs?

To improve the chances of early cancer detection, you should take your pet to your veterinarian at least once a year. Many veterinarians recommend animals over 6 years of age be seen twice a year. Your veterinarian will do a complete examination, checking your dog from head to tail to look 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 the eyes, ears and mouth

These exams are important because veterinarians can discover things that you may never notice. However, not all cancers can be detected by physical examination, so your veterinarian may also recommend screening tests like blood work, urinalysis and radiographs (X-rays), to uncover underlying diseases like cancer. Depending on the age, sex, and breed of your dog, your veterinarian may recommend one or all of these tests to help look for cancer.

Are some types of cancers more treatable than others?

Yes, all cancers are different and some are more treatable than others. The type of cancer, location, size, stage and response to treatment all affect the ultimate prognosis. With many cancers, the earlier the treatment is started, the better the prognosis, and ultimately, the longer the survival times. That’s why it is so important to bring your dog to the veterinarian for examinations at least once a year.

Do chemotherapy and radiation treatments affect dogs the way they affect human cancer patients?

While remission is the ultimate goal, quality of life is equally as 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 of cancer therapy in dogs, like with many other diseases, is early diagnosis and treatment. In order to give your dogs the best odds of beating cancer, make sure your dog gets regular check-ups, take advantage of recommended screening tests, and become familiar with the common signs and symptoms of cancer in pets so you can look-out for them at home. If you want to know more about cancer, speak with your veterinarian and visit Veterinary Cancer Society or Animal Cancer Foundation .

The Role of Comparative Oncology

Comparative oncology is the discipline that includes studying spontaneous, naturally occurring cancers seen in companion animals and expanding them into studies of cancer biology and therapy beneficial to both companion animals and humans.

Naturally occurring cancers in pet dogs and humans share many features, including histological appearance, tumor genetics, biological behavior, and response to conventional therapies. Tumor initiation and progression are influenced by the same factors for both human and canine cancer, including age, nutrition, sex, reproductive status, and environmental exposures. Several genetic alterations and molecular signaling pathways known to be important in human cancers have been defined and shown to be relevant in cancers of pet dogs.

Ten years ago when Luke Robinson, the Founder of The Puppy Up Foundation, and his two Great Pyrenees dogs, Hudson and Murphy, set out on their original walk from Austin, Texas to Boston Massachusetts to teach people about the growing epidemic of cancer in dogs, the field of comparative oncology was in its infancy. Since then, through efforts of The Puppy Up Foundation and other organizations, the science and importance of comparative oncology has become more well-known and developed.

The study of cancer in our companion animals is shaping our understanding of cancers in people, and leading to additional treatment options. According to a 2007 article by Philip J. Bergman, DVM, MS, PhD, DACVIM (Oncology) and Jeffrey Toll, VMD, DACVIM, the spontaneous cancers of pets treated by veterinary oncologists are similar to those arising in people. As examples, dogs and humans are the only two species that naturally develop lethal prostate cancers. The type of breast cancer that affects dogs spreads to bones – just as it does in women. And the most frequent bone cancer in dogs, osteosarcoma, is the same cancer that strikes teenagers.

Based on these similarities between humans and companion animals, veterinary cancer research benefits both animals and humans with cancer. In fact, The National Cancer Institute’s Center for Cancer Research has instituted a critical Comparative Oncology Program where veterinary oncologists are using naturally occurring cancers in animals to better understand and treat cancer in humans.

What’s Next?

Emotions run high when we hear the word cancer. Should your veterinarian suspect cancer in your pet, the first step is to obtain a definitive diagnosis, develop a treatment plan along with your vet or veterinary specialist, and prepare to be an advocate for your pet by arming yourself with information. Some other online sources of information include:

·   The Puppy Up Foundation
·   American College of Veterinary Internal Medicine, Oncology
·   The Veterinary Cancer Society
·   Abramson Cancer Center of the University of Pennsylvania
·   American Veterinary Medical Association
·   Cancer in the Canine
·   Texas A&M Veterinary Medical Center
·   Feline Cancer Resources
·   Emma’s Foundation