One of the hardest things about being a pet parent is that a majority of the time, people will outlive their furry friends.
Like humans, aging dogs and cats face a variety of ailments such as diabetes, joint problems, loss of hearing and eyesight. Another far too common disease that threatens both humans and animals is cancer.
Dogs get cancer at around the same rate as humans, according to the American Veterinary Medical Association. Nearly half of dogs ages 10 and up will develop the disease.
The Animal Cancer Foundation estimates roughly 6 million new cancer diagnoses are made in dogs and cats each year in the United States, with that number continuing to rise.
Like humans, dogs can suffer from several different types of cancer. Some of the more common cancers in dogs include mast cell tumors, melanoma, lymphoma and osteosarcoma. Cats are more apt to be diagnosed with mammary tumors, squamous cell carcinoma, fibrosarcoma and lymphoma.
Depending on the type of cancer and the stage of the disease at the time of diagnosis, treatment options include surgery, chemotherapy, cryotherapy and immunotherapy. For pet owners that opt not to treat the cancer, or if remission is unlikely, palliative care, which includes pain management, can be utilized to keep the pet comfortable until natural death occurs.
While there are treatment options, the Flint Animal Hospital at Colorado State University is conducting a study of a vaccine that might help prevent cancer in pets —specifically dogs —altogether.
Doug Thamm, a veterinary oncologist at the animal hospital, is conducting the Vaccination Against Canine Cancer Study, VACCS. The trial is the largest clinical study of canine cancer to date. Pet patients are being enrolled now.
The goal of the study is to evaluate how a cancer vaccine may prevent cancer in certain breeds of healthy dogs, potentially developing a new strategy to help prevent or control the spread of cancer in humans.
“Cancer is the leading cause of death in dogs and as a rank order, higher than people,” Thamm said. “Dogs don’t get a lot of the other things that kill people like heart attacks and strokes, which is what rises cancer to the top of the list.”
Interestingly, the types of cancers dogs get are very similar to cancers in humans, Thamm said. However, dogs get certain kinds of cancer more commonly than people do.
“But under a microscope, actually they all look the same,” Thamm said. “And that’s really kind of the reason why we feel like we can ask questions in dog cancer that might not only help out dogs and their owners, but help out people.”
Trials to incorporate around 800 dogs
CSU is one of three trial sites in the United States conducting the study. The University of California Davis and University of Wisconsin Madison are also participating.
Thamm definitely has some skin in the game, with himself being a double survivor of cancer and his wife being a thyroid cancer survivor.
“I had non-Hodgkin’s lymphoma when I was in my 20s, and I am currently being treated for a very benign leukemia made up of platelets called essential thrombocythemia,” Thamm explained. “My wife had (the cancer) removed surgically and takes pills to help stop it from coming back.”
Thamm’s experience with the disease and treatment made him wonder “what the deal was with cancer in animals” and helped him focus on veterinary oncology as a possible career track.
“I certainly can thank it for that,” he said.
CSU, as well as the California and Wisconsin sites, are looking for candidates for the study.
Dogs enrolled in the study will get either a vaccine or a placebo, have two health care visits with a cancer specialist twice per year, yearly blood work and financial support to treat any possible cancers they are diagnosed with.
“The actual participants in the study are getting real-time benefit, and at the end of the day, hey, maybe they get less cancer too,” Thamm said.
Pooches must meet specific qualifications
To be enrolled in the study, dogs must a set of qualifications that include:
- Owners must live within 150 miles of one of the participating trial sites
- Dogs must be between the ages of 5 1/2 and 11 1/2 years old
- Dogs must weigh at least 12 pounds
- Canine candidates can’t have any history of cancer
- No significant illnesses that could result in a life span of less than five years
- No history of autoimmune disease
- No current treatment with oral or injectable immunosuppressive medications
- Must be on the study’s eligible breeds list
“We are trying to capture dogs when they are getting into that age range where we typically see cancer more frequently, so that’s why that range of 5 1/2 to 11 1/2 years exists,” Thamm said.
Just as different races and ethnicities of humans can be more prone to certain cancers, like lung cancer in African Americans or breast cancer in Caucasian and Hispanic women, the same is true with cancer in dogs.
Thamm and his colleges are looking at how cancer develops in breeds including the Labrador retriever, French bulldog, German shepherd, golden retriever and the standard poodle. The study also is looking at cancer in mixed-breed dogs such as Doodles and Puggles. For a complete list of eligible breeds, go to the VACCS website.
“There are some really astonishing differences in cancer development in certain breeds of dog, which really lends credence to the idea that our genes are really important,” Thamm said. “The genes you are born with are probably pretty important in predicting your likelihood of developing certain kinds of cancer. There are a lot of folks studying that phenomenon. Like, why are Scottish terriers getting so much bladder cancer, and is there something we can learn about their genes?”
The reason the study is focusing specifically on dogs is that kidney issues are a leading health concern for cats.
“An awful lot of cats are going to run into issues with their kidneys before they get cancer,” Thamm explained. “But cats certainly do get cancer and very similar to the human cancers we see. Most of the cancers they get have human counterparts.”
Aside from typically being smaller than dogs, making it more difficult to get enough blood for tests, cats only make up about 15% of the animal hospital’s population, posing greater challenges in studying cat cancers.
Some of the signs of cancer in dogs and cats that pet parents should keep watch for include:
- Enlarged or changing lumps and bumps
- Sores or cuts that do not heal
- Sudden weight loss or weight gain
- A change in appetite
- Persistent cough
- Chronic vomiting or diarrhea
- Unusual or unpleasant odor from mouth
- Difficulty breathing, swallowing or eating
- Bleeding or discharge from any opening like nose or mouth
- Difficulty going to the bathroom
As with any odd or unusual symptom, the American Veterinary Medical Association recommends, “when in doubt, get it checked out.”
Vaccine developed by Arizona State University professor
The vaccine used in the trial was developed by Dr. Stephen Johnston, director of the Center of Innovations in Medicine at the Biodesign Institute and professor at the School of Life Sciences at Arizona State University in Tempe, Ariz.
“About 15 years ago I decided to see if we could develop a vaccine that would prevent cancer. It wasn’t a popular idea, but we thought it might be possible,” Johnston explained. “The initial intention was to do it in humans, but we had difficulty getting both funding and support for a clinical trial in people.”
However, when Johnston and his team proposed doing the initial trials on dogs, the study was approved and things began to move forward.
With so many different cancers and the instability of the disease, developing one vaccine that would affect all types might seem impossible.
“We discovered a source of what are called neoantigens that tumors make that stand out,” Johnston said. “Some of them were occurring across different types of tumors even in different patients. So we looked for those that were recurrent among the major cancers of dogs.”
Johnston found about 131 cancers with these similar neoantigens and chose 31 specific cancers to focus on for the vaccine study.
“We’ve learned a lot from this trial. What’s in the dogs now is antiquated,” Johnston said. “We know much better now how to make a vaccine now; we know better how to deliver the vaccine. So we are already designing the next generation for dogs and will probably get that into trial as soon as we can.”
The study is scheduled to take place over the next five years. Depending on the results, the veterinary community may be able to offer dog owners the opportunity to get their pooches vaccinated for cancer in the future.
“The scientifically most exciting thing is that if this works in dogs, I think it’s going to really help address some of the skepticism that the human cancer prevention community has about an approach like this,” Thamm said. “An awful lot of human cancer prevention specialists say that it’s not possible to design a vaccine to prevent cancer and they list off these reasons. And rightly so, but I think if there is data in dogs that live with us and drink the same water as us and get these tumors just like people do, it’s going to be really hard for those skeptics to say it’s not worth looking in to.”
For more information about the Vaccination Against Canine Cancer Study at Colorado State University, go to http://bit.ly/VACCS21.
