Lucky dogs. They're not bound by the social constraints we humans must endure. They can belch and fart whenever they please. They can take a bath (with their tongues, no less) in public. And certainly, no one begrudges a beloved pooch a few extra pounds around the middle. Why, it just wouldn't be a dog's life if you weren't able to enjoy a few extra calories every now and then, would it?
Obesity is considered the number one nutritional problem in dogs, and studies have documented that at least 25 percent of dogs in the United States may be overweight.
The scientists who conducted a just-released study would beg to differ. As it turns out, a dog's life can actually be extended if he's kept on a strict diet and not allowed to indulge too much in the dog food department.
The first-ever lifelong canine diet restriction study, sponsored by Nestle Purina PetCare, followed a group of Labrador retrievers for 14 years, from birth until death. The researchers found that a dog's median life span can be extended by 15 percent -- nearly two years for the Labs in the study -- by restricting the diet to maintain ideal body condition.
Forty-eight 8-week-old puppies from seven different litters were tracked in the studies. Puppies were paired within their litters according to gender and body weight, and then each puppy was randomly assigned to either a control group or a restricted-diet group.
All dogs were fed the same nutritionally complete and balanced diets appropriate for their age group, but those in the control group were allowed free access to food during 15-minute daily feedings. Dogs in the other group were fed 75 percent of what their paired littermates in the control group ate.
The dogs were weighed on a regular basis throughout the study, and beginning at age 6, their body condition was evaluated. Other healthy indicators -- including body fat mass, lean body mass, bone mass and glucose, glucose and insulin use, and cholesterol and triglyceride levels -- were also measured annually.
What researchers found isn't really a surprise -- veterinarians have stressed for years (often in vain) that owners need to keep their dogs lean and trim. Obesity is considered the number one nutritional problem in dogs, and studies have documented that at least 25 percent of dogs in the United States may be overweight.
The study's rather dramatic results, published in the Journal of the American Veterinary Medical Association, may lend more weight to veterinarians' arguments, and help convince owners that they may, in fact, be killing Fido with kindness.
To put it succinctly -- lean dogs live longer. The median life span (the age at which 50 percent of the dogs in the group died) of those in the lean-fed group was about 15 percent, or nearly two years, longer than that of the control group, researchers discovered.
Dogs in the restricted-diet group lived to a median age of 13 years, and 25 percent of the group survived to 13.5 years. Dogs in the control group only lived to a median age of 11.2 years, and none of the dogs lived to 13.5 years.
Only three lean-fed dogs had died by age 10, compared to seven control dogs. After 12 years, only one control group dog was alive, versus 11 lean-fed dogs.
"We all know that obesity, whether human or canine, is bad for health -- that's not new news," said Dennis Lawler, DVM, in a press release. Dr. Lawler, along with principal investigator Richard Kealy, Ph.D., led the study.
"What's exciting about this study is that, for the first time in a larger mammal, we proved that eating less resulted in longer life. That's powerful stuff," said Dr. Lawler.
Only three lean-fed dogs had died by age 10, compared to seven control dogs.
The study also showed that, from 6 to 12 years of age, the dogs on restricted diets maintained a significantly leaner body condition and, on average, weighed less, had lower body fat, and lost lean body mass later than the control group dogs as they aged. The researchers also observed that control dogs showed more visible signs of aging -- like graying muzzles, stiffened gaits, and reduced activity -- at an earlier age than the lean-fed dogs.
In addition to the veterinary ramifications, the study may well provide information valuable for human health.
"This study is significant for human as well as canine health because it's the first study completed in a larger mammal that proves the significant power that diet restriction wields in extending life and delaying the markers of aging," said Richard Weindruch, Ph.D., professor of medicine at the University of Wisconsin, in a Purina press release. "From this study, we can extrapolate that large mammals, including humans, can potentially live longer and healthier through diet restriction."
Article used with permission of Vetcentric.com. Copyright 2007. Erin Harty.
Written by Erin Harty