Analyzing your pet’s genome may shed light on human aging, mental health, and cancer.
Why would you want to swab your dog’s inner cheek, ship the sample cross-country, and perhaps shell out cold cash to learn the secrets contained in your canine’s saliva? Purveyors of dog-DNA test kits can supply plenty of reasons: Discover where on the planet Sparky’s fluffy ancestors likely snoozed and sniffed out their days. End that spousal debate about whether your mutt is mainly French bulldog or Boston terrier. Find out which breed-specific health conditions could afflict your beloved pet later in life.
But there’s a more human-centric reason, one that excites even geneticists who aren’t selling tests: Because canine genomics one day could save human lives.
Several commercial test kits of dog DNA are on the market, spurred by the sequencing of a complete dog genome in 2005 and falling lab costs since then. Meanwhile, research into canine genomics is surging at institutions including MIT and the National Institutes of Health. Improving veterinary medicine is the primary purpose of the academic work. Yet the researchers believe that studying canine biology could lead to a deeper understanding of human health and disease.
As with fetching, herding, and boring into our hearts with their very eyes, dogs are uniquely suited to this task.
Humans and dogs have a lot of medical matters in common. “Humans and dogs suffer from many of the same genetic conditions … and they live in the same environment and get many of the same health care treatments,” explains Adam Boyko, associate professor at Cornell University College of Veterinary Medicine and chief scientific officer of the dog DNA testing company Embark.
Plus, humans have spent centuries simplifying domestic dogs’ gene pool. The quest for certain traits has produced breeds whose members are so genetically similar that it’s relatively easy to spot genetic differences that could account for their varying health, sickness, or behavior. Already, canine genetic studies have yielded discoveries about illnesses such as narcolepsy, retinal degeneration, epilepsy, and certain cancers, all with human implications.
Dogs’ short lifespans make studying canine genomics a promising path to help us understand human aging.
The saliva swab alone is not enough to lead to big insights, for dogs or humans. To spot connections between genetic variations and health, researchers also need data on dogs’ physical traits, behavior, home environment, diet, and health over time — lots of it.
And this makes dog owners an essential part of the research mission.
“Pet dogs all live with humans, and humans are amazingly good at watching them and also really like to talk about them,” says Elinor Karlsson, director of the Vertebrate Genomics Group at the Broad Institute of MIT and Harvard and assistant professor in bioinformatics and integrative biology at the University of Massachusetts Medical School. Karlsson leads the crowdsourced pet-genomics project Darwin’s Ark (though she is personally — don’t hold it against her — a cat owner).
Cats and their owners aren’t entirely left out, though their DNA-test options are more limited at present. A complete feline genome was sequenced in 2007, and scientists have found some of the same genetic mutations underlying kidney disease in cats and humans. Cats also could provide a powerful model for studying infectious diseases, including AIDS. At least one cat-DNA testing company, Basepaws, conducts feline health research, as does the UC Davis Veterinary Genetics Laboratory. Darwin’s Ark intends to start collecting data on cats soon.
Meanwhile, researchers such as Karlsson and researcher-entrepreneurs such as Boyko rely on dog owners to provide essential information that a genome alone can’t reveal, as they pursue discoveries that could improve and lengthen dogs’ lives — and our own.
Here are five areas of human health where doggie DNA research is poised to teach us the most:
1. Extending lifespans
Most dog owners outlive their dogs. The pets’ sadly short lifespans may leave us bereft, but they also make the study of dog genomics a promising path to help us understand aging.
“Aging may be the area where canine genetics has the most to offer,” explains biologist Matt Kaeberlein, director of the University of Washington’s Healthy Aging and Longevity Research Institute and co-leader of the Dog Aging Project. Dogs age 7–10 times faster than humans, meaning that we can make discoveries about the biology of aging 7 to 10 times faster in dogs than in humans.
Also, “Big dogs age about twice as fast as little dogs,” says Embark’s Boyko, “and discovering the genetic causes of that difference might give us clues about how we can make dogs, and maybe people, live longer.”
Kaeberlein has started a Dog Aging Project Longitudinal Study to follow 10,000 dogs through almost their entire lifetimes, aiming to identify the factors in dogs’ genes and environments that cause some to live long, healthy lives while others die early. The same study in humans would take 70 years.
Participating pups will get annual vet exams and other tests. Their owners, meanwhile, will supply not only DNA samples but also information about the pets’ diet, activity, and home environment — essential data that is far more difficult to collect on humans.
2. Curing cancer
Almost half of all dogs over age 10 will develop cancer. Purebreds of certain breeds, such as golden retrievers, have an even higher risk. And humans’ experience of cancer is not so different from that of our canine friends. People and dogs get similar types of cancer, such as kidney cancer and soft-tissue sarcomas, and undergo surgery, chemotherapy, and radiation treatment.
If researchers can pinpoint genes that fuel cancer and affect response to treatment in the canine genome, they’ll have a starting point to search for cancer-related genes in humans.
“Because cancer risk is correlated with breed, we know genetics is important, but so far we don’t know that much about the genetics of canine cancer,” Boyko says. “With large-scale studies … we think we can identify the genes underlying both cancer risk and cancer resistance in different breeds.”
Dogs could teach us a lot about how something as mechanical as a gene, which codes for a protein, can translate into something as complex as behavior.
Austin-based Embark aims to do some of those studies, in collaboration with Cornell, using the DNA and health data that dog owners provide when they send in their $199 test kits — if owners opt to participate. Find My Pet and Wisdom Panel offer a simpler set of results for around $85-$90. Wisdom Panel also uses such data to conduct health research.
The NIH has been researching canine cancer genes for well over a decade. The Institute’s Dog Genome Project is currently seeking DNA samples from Portuguese water dogs, Scottish and West Highland terriers, flat-coated and golden retrievers, Rottweilers, standard poodles, and other breeds (even mutts) with certain cancers.
3. Understanding genetic disorders
Cancer is hardly the only disease driven by genes. Nearly any ailment — or our response to it — could have roots in genetic differences as yet undiscovered. With more than 350 inherited diseases already identified in dogs, many of which also occur in humans, it’s no wonder researchers are combing canine chromosomes for clues to which genes influence them.
The simplest genetic links to identify are those where mutations in a single gene cause a disease. This kind of work has already led to discoveries that stand to help humans.
For example, Stanford University researchers in 1999 pinpointed a gene in Dobermans and Labradors that, when altered, causes canine narcolepsy. That led to the discovery that humans with certain narcolepsy symptoms have problems with the same brain chemical that’s affected by that dog gene. More recent studies have revealed mutations that cause retinal disease leading to blindness in dogs and humans, and gene therapies for both species are being studied.
Canine genomics research is expanding into more areas of dog health that also affect humans. Potential targets include dilated cardiomyopathy (a kind of heart disease that’s common in Dobermans and can be life-threatening in people), hip dysplasia, and obesity.
4. Probing genetic influence on behavior
To link behavior in sniffing, slobbering dogs with that of humans may seem like a leap — especially when you’re watching your pup chase sprinkler streams or bark at a washing machine. But here again, breeding has molded dogs into model subjects.
Certain breeds have been cultivated for specific traits and tasks, and those tendencies are certainly conserved in their genes. So dogs could teach us a lot about how something as mechanical as a gene, which codes for a protein, can translate into something as complex as behavior.
The dream of understanding how genes drive behavior is what got Karlsson into canine genomics in the first place. Her project, Darwin’s Ark, is building a massive public database of genetic and health information from tens of thousands of dogs. Pet owners send DNA samples and health surveys and get back breed identification for free (or for a fee, if they want more information faster). Unlike commercial testing services, which spot-check a dog’s DNA for specific codes, Darwin’s Ark sequences each dog’s entire genome.
Dogs, like humans, suffer from compulsive behaviors they can’t stop repeating, like spinning, barking, or chewing.
“People are always asking me: ‘How many dogs do you want?’” Karlsson says. “And I’m like, ‘Well, really, all of them.’ Because the more information you have, the more you can learn.”
For example, dogs, like humans, can suffer from compulsive behaviors that they can’t stop repeating. Canine compulsions may include spinning, barking, or chewing. Compulsive disorders come on in early adolescence in both humans and dogs. They’re treated in both species with the same drugs, with equally unreliable results. And they’re highly heritable in both species.
Already, Karlsson has found evidence that some of the same genes involved in dogs’ compulsive disorders could be present in humans. The fact that the drugs work similarly “really suggests that the same brain pathways are probably involved in some of these diseases,” she says, which may lead to new treatments.
5. Fighting food allergies
Grocery stores often stock “allergen-free” or “grain-free” dog food just an aisle or two away from peanut-free sunflower butter and gluten-free bread for humans. Dogs have food allergies less often than their owners may suspect, but some truly do.
A dog’s allergic reaction doesn’t look like the sudden, life-threatening inability to breathe that can strike people with, say, a severe peanut allergy. Instead, canines have a longer, slower response that can cause digestive problems and itchy skin. Genes probably play a role in either case.
So Karlsson is working with the Broad Institute’s Food Allergy Science Initiative to glean insights from dogs that could be applied to humans. Her surveys for dog owners ask about eating habits, such as picky eating, and her team has started analyzing the links between those traits and genes.
For the tens of millions of people with food allergies — a number that’s rising for reasons hard to understand — clues from the canine genome can’t come too soon.
