Veterinary research can sometimes appear to have little relevance to what dog owners care about most. Investigations delve into minutiae while we want answers to the big questions. But two recent research papers deal with possibly the biggest of big questions — how to prolong life.
In the first, 48 Labrador retriever puppies from 7 litters were divided into 24 pairs based on their gender and weight at weaning. One dog from each pair was randomly designated to be the control, while the other was fed 25% less than what the control dog ate. The study ran from when the dogs were eight weeks old until they died. The pair was housed together with access to both indoor and outdoor areas and no restriction to their activity levels. The dogs received standard preventive care and medical treatment as necessary. At three years of age, all the dogs were switched off of puppy food to an adult maintenance diet and the control dogs were fed an amount that should have maintained them at an “ideal” body weight.
The result of a 25% reduction in caloric intake was profound. On average, these dogs lived almost two years longer than those dogs who were fed a “normal” amount. In addition, the calorie-restricted dogs developed fewer chronic diseases like osteoarthritis, and when they did occur, they developed later in life. This is what we all want for our dogs — a long, healthy life, and if disease has to come, let it come as late as possible.
I found the next study equally interesting. Researchers on the human side of things have noticed that Parkinson disease patients who take L-deprenyl not only experienced fewer symptoms but also lived for longer than did other patients, even when demographic differences between the two groups were taken into account. Scientists decided to see whether a similar effect occurred in dogs.
They paired 82 beagles ranging in age from 2.8 to 16.4 years and gave one individual a placebo and the other L-deprenyl for over two years. Due to the inclusion of so many young dogs and the relatively short duration of the study, no overall difference in life expectancy for the two groups was noted (we’d expect 3 year old dogs to live for another couple of years). However, when the researchers looked only at dogs who were between 10 and 15 years of age at the start of the study and received L-deprenyl for at least six months, the results were quite different. Eighty percent (12/15) of the dogs who received L-deprenyl lived until the end of the study, while only 39% (7/18) of those who didn’t survived.
I’m not at the point where I’m recommending that all older dogs receive L-deprenyl in an effort to prolong their lives, but when presented with a patient who might otherwise benefit from the medication, say a dog exhibiting signs consistent with early canine cognitive dysfunction, I will be more apt to prescribe it and recommend a dog stay on it for life.
On the other hand, I do recommend that most healthy dogs be fed in such a way as to mimic a 25% reduction in caloric intake. Keep your dog on the skinny side and you just might have him around for a couple of years longer than you would otherwise.
Dr. Jennifer Coates
Metabonomic investigations of aging and caloric restriction in a life-long dog study. Wang Y, Lawler D, Larson B, Ramadan Z, Kochhar S, Holmes E, Nicholson JK. J Proteome Res. 2007 May;6(5):1846-54
Treatment with L-deprenyl prolongs life in elderly dogs. Ruehl WW, Entriken TL, Muggenburg BA, Bruyette DS, Griffith WC, Hahn FF. Life Sci. 1997;61(11):1037-44.
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