The medical truths about cats and dogs

Garnet, a long-haired tabby, lies on a plush blanket on an operating table at the Ontario Veterinary College’s new animal cancer centre at the University of Guelph.

The five-year-old mews a small protest as a veterinary technician inserts a chemotherapy catheter in his shaved hind leg. Blue-gowned staff on the other side of the table stroke his coat and lavish him with compliments. Soon he has relaxed into gentle belly rubs during his 15-minute treatment.

Garnet has lymphoma. A neck tumour, blocking 85 per cent of his airway, has been surgically removed, and he has had a course of radiation therapy. But a subsequent CT scan and ultrasound have shown the cancer has spread to his kidneys.

Garnet’s owners — Acton, Ont., empty nesters named Patti and Brian Resch — have decided on chemotherapy for their furry family member in hopes that it will give their “stay-at-home child” a year of quality life.

“My husband had lymphoma,” explains Patti. “He was given a five-year life span, and was put on experimental cancer treatments, which include many of the drugs we’re using on Garnet.” Brian’s cancer has been in remission for 25 years.

“We fought hard for Brian. We’re going to fight hard for Garnet.”

They’re not alone. A growing number of people are battling to improve the health — and save the lives — of their pets using a growing arsenal of technology and treatment.

In the past two decades, “the quality of veterinary medicine has been skyrocketing,” says Jean Gauvin, a small animals GP in Montreal and the vice-president of the Canadian Veterinary Medical Association. It has, he says, “revolutionized” his practice. Stem-cell therapy for arthritis and pacemakers to regulate pets’ hearts would have been unheard of just a few years ago.

Today, there are 40 distinct specialties of veterinary medicine, including cardiology, dermatology, neurology, ophthalmology and radiology. Sports medicine clinics, complete with treadmills and swimming pools, help pooches recuperate after orthopedic surgery. Cats and dogs wear braces to reposition misaligned teeth.

Even alternative treatments such as acupuncture are used to ease chronic pain, arthritis and allergies.

And a robust industry of behaviour specialists has emerged to treat dogs for separation anxiety, storm phobias and aggression.

Most of the advances in veterinary medicine are the result of adapting procedures, treatments and medications from human medicine. But the flow of benefits also goes the other way. Cutting-edge research on pets could benefit humans, too, because the basic physiological structures of cats and dogs aren’t all that different from ours.

Cancer care is an excellent example of a subspecialty of veterinary medicine that has made huge strides in recent years, with exciting implications for both animals and humans.

The Ontario Veterinary College’s Pet Trust Fund, a charitable organization that supports the health of companion animals, has pledged $ 15 million for the Mona Campbell Centre for Animal Cancer at the University of Guelph.

The centre opened last fall and boasts Canada’s most comprehensive centre for animal cancer care — including surgery, radiation and chemotherapy. There’s even a counsellor on-site to help pet owners make tough decisions about continued medical intervention. Treatment may not cure the disease, but it can give the animal up to three years of life — a huge benefit in pet years.

As with humans, cancer becomes more prevalent as pets live longer. About one in eight cats and one in four dogs die from cancer.

At the Guelph centre, 80 per cent of the patients are dogs — cats tend to travel poorly and make for uncooperative patients. Other pets, such as ferrets, are also treated. Each week, they schedule about 100 appointments, about 20 of which are new patients. In its first year, they expect to treat up to 1,500 pets.

The 12,000-square-foot facility has a linear accelerator with on-board imaging for radiation therapy that precisely targets the tumour. These accelerators are commonly used on humans but the Campbell Centre is the only one in Canada for animals.

Most patients are from central Canada, but some travel great distances to access treatment that can cost up to $ 10,000. A cocker spaniel travelled all the way from Korea; another cocker spaniel came from Nova Scotia by car for weekly radiation therapy; a golden retriever from the Prairies underwent radiation therapy while his owners camped nearby in an RV.

Treatment costs vary, depending on the severity of the disease and the scope of the treatment.

A consultation costs $ 150. Radiation therapy for palliative purposes, or to reduce pain, costs between $ 400 to $ 600, whereas doses intended to cure the animal or to improve symptoms may cost from $ 4,000 to $ 5,000.

A straightforward surgery, such as the removal of a mast cell tumour on the skin will cost $ 300 to $ 500. But a more complicated surgery (such as removing a tumour from the face — requiring advanced imaging with a CT Scan or MRI), surgery for curative intent and recovery in the intensive-care unit — can cost up to $ 3,000.

To date, Garnet’s cancer care has cost about $ 5,000 and the Resches expect the figure to reach $ 8,000. When asked why they would spend that much money to buy Garnet a year of life, Patti replies, “He’s worth it.”

The centre’s medical oncologist Paul Woods explains, “The pet is part of the family.”

“We have people for whom the investment of money is certainly there, but also the time, emotion and effort,” says Woods, who’s also a professor of oncology in clinical studies.

Pet chemotherapy isn’t as intense as that administered to humans, nor do animals experience as many adverse effects. But hair loss can occur among dogs, especially small breeds, such as poodles, bichons and schnauzers. Cats typically lose their whiskers.

Many pet owners are attracted to the Campbell centre for the experimental therapies and clinical trials offered through the university’s Institute for Comparative Cancer Investigation, which is comprised of 30 scientists from cancer-related fields, such as biology, nutrition, psychology, chemistry and toxicology. Many of these scientists work with patients at the animal cancer centre.

The university is the only Canadian member of the U. S. National Cancer Institute’s Comparative Oncology Trials Consortium, a network of 20 universities that run clinical trials in dogs before taking them to human trials. Because pets share our environment, they may provide clues that lab rats artificially induced with cancer cannot.

In fact, some cancers in pets and humans are so alike that they share the same tumour biology and behaviour. The bone cancer called osteosarcoma that killed Terry Fox is an example of a tumour that behaves similarly in humans and dogs, often targeting big breeds such as great danes and greyhounds. The cancer occurs in the same location of the bone and spreads to the lungs. New treatments that benefit dogs, could translate into treatments for people.

Similarly, dogs and humans are both prone to lymphoma, melanoma and bladder cancer, so research on canines might have implications for humans. (Meanwhile, lung, prostate and colorectal cancers — big killers of humans — are not common in pets.)

The centre has developed a tissue bank for tumours and normal tissue from animals so scientists in the future can study biomarkers, proteins and gene expression.

“The tumour bank is an investment for the future, for novel targets for treatment that we haven’t even dreamed of yet,” says Woods.

When it comes to Garnet’s future, his owners say that when the time comes to cease treatment, they’ll be ready.

“It’s a very fine line to draw: Who is this for? Him or me? Right now, it’s for all of us,” says Patti Resch. “If (treatment) was going to make him suffer or prolong a suffering, I think we’re strong enough to let him go. I know we are.”

But for now, Garnet is loving life, hanging out with the other family cat — a black long-haired domestic named Shadow — and cuddling up with her owners.

“Anyone coming into the house would never ever know I’ve got a sick cat.”

How pets might help their humans

A number of advances in cancer research have been developed as a result of mapping the human, mouse and dog genomes, which gives scientists a better handle on how cancers mutate in different species, says veterinary medical oncologist Tony Mutsaers. Much of his research at the Ontario Veterinary College at the University of Guelph involves studying the three species to pinpoint what’s causing the genes to mutate and then targeting them with treatment.

“We look at the human samples that we’re able to obtain from collaborators at human institutions and our samples and scan those together to look for cancer-driving mutations or cancer processes that occur across all three species,” explains Mutsaers.

Among current projects:

• Researchers are testing for the presence of a specific biomarker that seems to affect the response to chemotherapy in dogs with lymphoma. If the dog has the biomarker it can be switched to an alternative treatment sooner. This approach could also benefit people.

• Because low vitamin D in humans is linked to an increased risk for cancer and a poor prognosis, another clinical trial involves studying the vitamin D levels in dogs diagnosed with lymphoma, osteosarcoma and mast cell tumours and comparing them with healthy dogs.

• A joint study with McMaster University involves cats with breast cancer. The aim is to test a new agent and see if it is capable of activating the immune system to fight the cancer. If successful, the agent may go on to human trials.

• Researchers are testing a serum biomarker to identify hemangiosarcoma, a cancer of blood vessels that often affects the spleen and liver, which may cause them to rupture and bleed into the abdomen. They’re looking for a protein present in the blood of dogs with the disease, with the hope of providing early diagnosis and treatment. This cancer often affects Golden retrievers and German shepherds. (In humans, this cancer is called angiosarcoma.)

• Along with researchers from the Lawson Health Research Institute, in London, Ont., clinicians are investigating whether advanced imaging with a PET-CT scanner will reveal dogs with mast cell tumours responding to targeted chemotherapy earlier than monitoring with conventional radiographs and measurements.

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