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Have We Found the Canine Fountain of Youth?

Old Dog

After Sasha's 15-and-a-half-year-old chow-vizsla mix passed away in her arms, she vowed he would be her last dog. She could not bear the sadness of losing a beloved pet again.

The tragedy that befalls a family after one of its furry members moves on is well-known, especially because our four-legged friends live for only a fraction of the time we do. Fortunately, studies are pointing to a cancer-fighting drug called Rapamycin currently used successfully in human patients that could extend the life of man's best friend.

"These were serendipitous findings," said University of Utah veterinary pathologist Roger Van Andel, DVM, PhD. "Through mechanisms we don't completely understand, Rapamycin does seem to extend the life of various species by differing amounts." These species range from single-celled organisms like yeast to small mammals like mice. Researchers are hoping the drug could have similar effects on canines and even humans.

While it is unclear exactly how low doses of Rapamycin work to extend the lifespans of mice and other organisms, there are several theories. One is simply that, as a cancer-fighting drug, it works to reduce the rate of cancer development. Another theory focuses on inflammation.

"Certainly, the processes of growing up and aging and ultimately dying are very complex," said Van Andel. "One thing that we have found in the past several years is that inflammation itself is a huge contributor to disease and aging." Rapamycin, along with its anti-cancer effects, also appears to be a powerful anti-inflammatory agent and may contribute to the extended lifespans of study subjects, said Van Andel.

It's not exactly the Holy Grail, but researchers at the University of Washington's Dog Aging Project have been studying the effects of Rapamycin on the hearts of dogs and noted that the hearts in dogs given the drug started to function better. Van Andel believes this phenomenon may be due to the drug's anti-inflammation properties in cardiac muscles, which are affected by a lifetime of inflammation.

The idea of the study conducted by the Dog Aging Project is to extend the healthy, active life of a middle-aged dog rather than to prolong the more painful, sickly years of old age.

But let's not get our hopes up too quickly, warns Director of Drug Information Service at University of Utah Health Erin Fox, PharmD. "Certainly, this is very much in the clinical trial phase of things," said Fox.

Furthermore, the drug approval process takes time and it may be five to 10 years before we see an approved application of Rapamycin for our dogs, said Van Andel. "Rapamycin has a number of really nasty side effects," he said of the high doses given to humans for cancer treatment.

Van Andel, who has had three dogs die of cancer, said he would be tempted to give the drug a try on his own pets in the future as long as its low-dose regimen has been proven to have no unintended side effects.

Sasha's daughters, missing the friendly presence of a dog in the house, finally persuaded their mother to adopt a loving hound puppy from a local rescue program. Even if the dog, Elvis, were to live as long as Sasha's last dog, he would probably still not outlive his human mom. But by keeping his heart healthy through exercise and diet, and potentially Rapamycin, Elvis may just be bounding around the park, fetching tennis balls and sleeping at Sasha's feet for many more years to come.