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The big news this fall in canine nutrition is an energy bar designed to recharge a hard-working dog’s ability to continue hunting, and I have to say it’s the most fine-tuned example of microbiological engineering I’ve ever seen. It isn’t the old “candy bar” fix, which provides a brief sugar boost followed by a deeper low. Nor is it a supplement that has to be fed daily. And it doesn’t upset the balance of nutrients in premium or other dog foods. What it does is focus solely and efficiently on resupplying muscle with glycogen, a carbohydrate essential for energy. When glycogen stores are depleted, muscle fatigue sets in and performance becomes limited.

In one human study, athletes who ran 16 miles a day for three days started the third day with smaller glycogen stores than they had at the end of the first day. Their fatigue was greater and their times reduced. Exercised dogs fed normal meals regained only 65 percent of their glycogen stores in 24 hours.

Arleigh Reynolds, DVM, PhD, DACVN, who wrote a paper on glycogen repletion in 1997, has been researching canine nutrition with sled dogs for five years in Alaska with Purina. Before that he was a professor at Cornell. Purina’s new Pro Plan Performance Bar was created largely through his expertise. Here’s how it works.

Glucose in the blood is the building block of glycogen. During exercise, special glucose transporters allow rapid entry through the muscle surface. Transporters remain on the surface for only about 30 minutes after exercise before they’re internalized, allowing a very small window of time in which to feed the bar. It should be given as soon as heavy panting stops, preferably within 10 minutes and no more than 20.


The type of carbohydrate in the bar is also fine-tuned. Candy-bar sugars, while rapidly absorbed, require lots of water to process glucose and cause high insulin spikes. If inadequate sugar remains in the bloodstream for the spike’s duration, low blood sugar (hypoglycemia) can result. Fructose and some corn syrups are liver-processed, which takes longer than the transporters remain on the muscle. Grain starches digest too slowly to match the time window. Between the fast-digesting simple sugars and the slow starches is a moderately fast carbohydrate called maltodextrin, which seems most efficient in supporting glycogen replenishment. It is the main ingredient in the Pro Plan Performance Bar.

For optimum performance, feed half a bar per 50 pounds just before exercise and every hour during hunting. Then feed your dog a whole bar within 10 minutes of the end of exercise.

The one concern held by some owners of hard-working dogs is that the bar might cause injury by pushing the dog beyond natural limits. “Not so,” says Reynolds. “The Performance Bar doesn’t push dogs further than they can go. It helps them reach their potential. They’re not tired, so they won’t get hurt. When dogs with great hearts become tired and keep going, that’s when they get hurt.”

Optimum Plan

Underconditioned dogs can certainly benefit from the Pro Plan Performance Bar, since they have less stored glycogen and actually rely on it more. However, the best plan is to condition the dog in addition to feeding it the bar. Muscles become trained to burn fat, which the well-conditioned dog stores at a ratio of 50 calories of fat to 1 of carbs. A conditioned dog can cruise on fat energy, saving glycogen for bursts of intense exercise, and not deplete glycogen stores when hunted several days in a row.

Quick Tip

CHOW CHECK According to Dr. Reynolds, the best time to check a dog’s ribs for proper weight is when the dog is eating or inhaling deeply. The sucking-in action makes the “rib check” easy and accurate.

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