Most dogs get poked and prodded at the veterinarian's office. Piper, a 4-year-old golden retriever in Chicago, gets far more scrutiny than that.

Her annual checkup this month took three hours. Her flaxen hair was trimmed and bagged, her toenails clipped and kept, her bodily fluids collected.

Everything was destined for a biorepository in the Washington suburbs that holds similar samples from more than 3,000 other purebred golden retrievers from across the country.

The dogs, though they do not know it, are participating in an ambitious, US$32 million research project that researchers hope will yield insights into the causes of cancers and other diseases common to goldens, other breeds and maybe even humans.

All the dogs were enrolled in the Golden Retriever Lifetime Study before they turned 2, and all will be closely tracked for their entire lives. The researchers, from Colorado State University and the Morris Animal Foundation, are not just analysing biological matter.

They're also compiling exhaustive data, recorded and reported each year by the dogs' owners, on every aspect of the pooches' lives: what they eat, where they sleep, whether their lawns are treated with pesticides, whether their teeth get brushed and more.

Longitudinal studies like this - with information gathered in real time - help researchers detect causes and effects that might be missed in other kinds of studies.

Some focused on humans who have tracked thousands of babies born in the United Kingdom during one week in 1970 and monitored the cardiovascular health of residents of Framingham, Massachusetts.

But this is the first and largest lifetime longitudinal study of pets, and the hope is that it will shed light on links between golden retrievers' health and their genetics, diets, environments and lifestyles.

Some of "these dogs will get cancer as they age … but in the meantime, they are doing everything that dogs do," said principal investigator Rodney Page, a veterinary oncologist who directs Colorado State's Flint Animal Cancer Center.

As for tracking the minutiae of participants' lives, "some of these things seem kind of silly, but you never know what you're going to identify as a significant risk factor with an outcome that you could easily change."

That information, by extension, could be useful for other breeds, as well as people, who develop cancer and respond to treatments in similar ways to dogs.

At its core, the study is about cancer - what Page calls "the No. 1 concern among dog owners".

The disease is the leading cause of death in dogs over age 2 and something diagnosed in half of dogs older than 10.

The prevalence is believed to be slightly higher in golden retrievers, which most often succumb to mast cell tumours, bone cancer, lymphoma or hemangiosarcoma (originating in the lining of blood vessels).

From left, Shelby and Gretchen. (Marvin Joseph/The Washington Post)

But that is not the only reason the bouncy, amiable breed is the study's focus.

Goldens are the third-most popular dogs in the United States, which made it easier for researchers to find 3,000 subjects; they also tend to have besotted owners who pay close attention to their health - an important criteria for a project that demands years of owner commitment.

Golden retrievers "are right beside us when we're running, when we're having dinner, when we're out traveling. They basically reflect a lot of the same exposures and activities that we have," Page said.

The study began in 2012. It has produced no major revelations yet; its oldest participants are 7 and not widely afflicted with cancer or other ills. But annual surveys have yielded interesting tidbits about the dogs' lives.

One in five sleeps with its owner. Forty percent swim at least once a week. Twenty-two percent drink or eat from a plastic bowl, and about one in four eats grass.

And the researchers' prediction - that the breed's owners would be an enthusiastic study group - has been validated. They have an incredibly active private Facebook group, plus local meetups with their "hero" pets.

"We have a really passionate cohort, is the best way to describe it," study veterinarian Sharon Albright said.

When a Chicago golden named Piper briefly fell ill last year, her owner, Joe Brennan, posted a photo of her wrapped in blankets to the Facebook group. More than 100 well-wishers quickly responded, he said.

Brennan and his wife had enrolled Piper in the study shortly after they purchased her from a breeder. Brennan's mother had two golden retrievers that died of cancer, and he said he wanted "to give back and maybe play some tiny part" in reducing the breed's risk for the disease.

And one of the conditions as Kelly Hinkle adopted Maizie in 2016 was that she keep the 2½-year-old dog in the study. "I'm like, 'Of course I'd continue!' " said Hinkle, a Silver Spring, Maryland, veterinarian who was especially excited by the project's emphasis on exposure to both inside and outside environmental factors.

"A lot of common things, like hip dysplasia, that's the way they're bred," she said. "But getting tumors or cancer - is that a genetic thing or something we've done throughout their lifetimes to cause that?"

Although cancer rates may be higher among golden retrievers, they're not necessarily increasing. Cancer is a disease of older age, and today's dogs, which mostly stay indoors and see vets more often than their ancestors, are living longer.

Experts say the prevalence in goldens may be partly explained by their sheer abundance.

"Do you see a lot of goldens that have skin diseases? Do you see a lot of goldens that have flea allergies? Yes," said Jaime Modiano, a canine cancer researcher at the University of Minnesota's College of Veterinary Medicine who is not involved in the study.

"Golden owners as a group tend to be very attentive and attached to their dogs," and so they seek out care when they suspect a problem.

The project's focus on golden retrievers might be an inherent limitation, said Modiano, whose lab has done multi-breed studies that found certain genetic markers create a higher level of risk in some kinds of dogs. "If you look at a single breed, you're going to lose part of the picture," Modiano said.

Still, the study's large sample size and systematic, controlled approach will yield data that could fuel research on questions that go well beyond cancer, he said - such as whether goldens in some geographic regions or with certain traits, like size or coat color, are more or less likely to have particular conditions.

"Being able to discriminate random chance becomes a lot easier when you have large numbers," he explained. "It really is ambitious, and the treasure trove of material that they are going to get will be remarkable."

Gathering all this data depends on owners, whose vet visits are subsidised. One is Matt Morley, a lawyer in Chevy Chase, Md., whose retriever, Hayley, had lymphoma and died in 2013. He enrolled her successor, Nellie, in hopes of helping other dogs as well as people.

"Whatever they learn in this study could have real human applications," Morley said. "All the drugs my original dog was taking, they're all drugs that people who have cancer take."

Owners commit to spending a few hours for the study every year. They say goldens are well worth it.

"They're the smartest dogs ever," Brennan gushed. "They're the most loyal things you'll ever meet in your life."

Piper was found to have a bit of hip dysplasia but no other issues at her recent exam, where Brennan snapped a photo of her. It shows her sitting proudly, wearing a green bandanna printed with a yellow silhouette of a golden retriever and the words "Study Enrolled Dog."

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This article was originally published by The Washington Post.