by Chip Reid / CBS News

SPRINGFIELD, Va. ( –  The sweet and playful golden retriever is one of the most popular dog breeds in America, with a special talent for getting even so-called grown-ups to join in the fun. But, as Kris Campesi has learned through painful experience, they also rate high on another scale.

“Goldens have a high probability for cancer,” she explained.

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That rate is about 60 percent, one of the highest in the dog world. Campesi recently lost one golden to cancer and now 7-year-old Malachi has a brain tumor.

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“They’re such a part of your life, and when it’s time for them to go it’s hard,” Campesi said.

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Kris Campesi has a dog in a nationwide cancer research study for golden retrievers / CBS NEWS

Looking for answers, she entered 3-year-old Nicodemus, who’s perfectly healthy, into a national study of nearly 3,000 golden retrievers. The goal is to understand why the cancer rate is so high.

“I have to keep track of everything they eat, the water they drink, the chemicals I use around the house,” Campesi said.

Nicodemus even has something called a “whistle” that stays with him all the time so it can record his activity and sleep.

Veterinarian Laney Rhymes takes samples of his hair and nails during frequent medical exams.

“They’re looking for environmental stuff that the dogs might be exposed to that would concentrate in the nails,” Rhymes said.

Even while he’s giving blood, that tail keeps on wagging. Campesi hopes the study will eventually help all dogs including hers to live longer lives. She’s not the only one who hopes that will be the case — Nicodemus is also a therapy dog for special needs children, and they’re counting on him to live a long and healthy life.