How Dogs Fight Cancer

Man’s best friend is becoming a key player in fighting cancer, allowing scientists to speed up the process of connecting dots between genetics and disease

A dog named Maz collects on his psychic debt.
A dog named Maz collects on his psychic debt. Photo courtesy of Carol Ryder

If, like me, you have dog that can sense when you are feeling particularly indebted, you might want to make sure he or she isn’t in the room when you read this.

Because now their species is becoming a key weapon in fighting human diseases, particularly cancer.

As William Grimes pointed out in The New York Times last week, doctors and veterinarians are working together more than they ever have before, exchanging notes and insights about their research and seemingly dissimilar patients.

One reason is that treatments that work on mice and rats too often are frustratingly ineffective on humans. At the same time, an approach called “one medicine” is beginning to take root, based on the recognition that 60 percent of all diseases move across species, as do the environmental factors that can help cause them.

“Dogs live side-by-side in our environments with us,” notes Elaine Ostrander, genetics researcher for the National Human Genome Research Institute at the National Institutes of Health. “They drink the same water, they breathe the same air, they’re exposed to the same pesticides and they often eat some of the same food.”

It’s all about breeding

Last month Ostrander published a study in the New England Journal of Medicine that explained why, when it comes to making connections between genetics and disease, dogs are so special.

It has everything to do with breeding. By selectively mating purebreds to excel at a particular behavior or maintain a specific body shape or hair color, breeders also limited their genetic diversity and made them more susceptible to diseases carried through recessive genes.

But it’s that clustering of genes that’s helping to speed up the process of connecting the dots between a genetic mutation and a particular disease. For instance, several dog breeds are prone to epilepsy, and researchers have been able to identify the genes responsible. The hope is that will help pinpoint what’s happening in humans.

Same thing with cancer, the number one cause of death in dogs. Chromosome changes seen in some canine cancers have been similar to what’s been observed in humans with the same kind of cancer. By focusing on what parts of genes are altered in both species, the number of potential target genes can be reduced to a handful.

Learning from dogs

In one study, Matthew Breen, a researcher at North Carolina State University, tracked 150 dogs with lymphoma. He and his team were able to identify a genetic indicator that predicts how long a dog will respond to chemotherapy, and he believes that that knowledge could help refine treatment for humans with lymphoma.

Says Breen: “Within the canine genome, we’re starting to find the answers we’ve been looking for in our own genome for 50 years.”

In another dog cancer study at the University of Illinois, researchers found that a particular type of virus that doesn’t harm humans or dogs was able to invade dog cancer cells and leave healthy cells alone. The scientists also determined that a version of the virus with a single gene deleted was four times better at killing cancer cells.

It’s only a first step, but it shows promise as a cancer treatment for dogs that could do far less collateral damage than chemotherapy or radiation–and could one day be used to treat humans.

Adds lead researcher Amy MacNeill:

“We wanted to make sure that the dog cells were like the human cells because we want to use these viruses not only to cure dogs of cancer but also to use the dogs as better models for humans with cancer. People are beginning to see the logic of this approach.”

Dogs in diagnosis

Here’s more recent medical research involving connections between dogs and humans:

  • Help me help you: Researchers at the University of Pennsylvania School of Veterinary Medicine are using an experimental treatment on a handful dogs with osteosarcoma, a form of bone cancer. If the therapy is successful–it involves introducing bacteria to provoke their immune systems to kill cancer cells- it could be used in trials on humans.
  • Magic mushrooms?: In another study at the University of Pennsylvania, scientists found that a mushroom used in Chinese medicine for 2,000 years has been effective in treating dogs with hemangiosarcoma, a particularly nasty blood cancer that attacks the spleen. It too could one day be tested in human clinical trials.
  • Going ’round in circles: It sure can look funny, but a recent study in Finland came to the conclusion that a dog chasing his tail is a canine variant of obsessive compulsive disorder in humans.
  • I feel your pain. No, really: Several new studies say that dogs’ brains may be hardwired to comfort humans in distress. The majority of dogs in one of the studies tried to calm people with licks and nuzzling when they pretended to cry–even if they weren’t their owners.
  • So why does he keep grabbing my hair?: A study of more than 5,000 babies in Australia found that they were less likely to develop an egg allergy if there was a dog in the house.
  • And 50 percent of it gets on you: And finally, researchers at Georgia Tech determined that a wet dog can shake off 70 percent of the water on its fur in four seconds. For that alone, dogs deserve props, but the scientists think this uncanny ability could some day lead to self-drying machines on equipment.

Video bonus They help us fight cancer and catch Frisbees?

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