I guess the most common question I get around field trials and hunt tests involves something to "give my dog a boost". This desire for helping dogs perform better is reflected in the dozens of products for sale that offer nutritional supplementation. If we look closely at the energy needs of hard working dogs, we can make a better choice as to which product to buy and even if we need to supplement our hunting dogs.
In my view, the very best supplement available is just another handful of dog food. The commercial diets available for hunting dogs today (the one's with the word performance in their brand name) offer a balanced, complete nutritional matrix that outperforms any magic powder you mix in the food or in the dog's water. Most dogs that I see professionally that are off in weight or lacking stamina either have a medical condition or they are not getting enough of the right kind of dog food. This means 20% fat on the bag's label from a respected manufacturer.
Fat is where it is at for hunting dogs. These high-fat diets allow for maximum energy usage. Even dogs that are soft and out of condition perform better when fed a high-fat diet. Ideally, the dog is fed this type diet for at least 8 weeks before hunting season begins to allow for the little energy furnace in muscle cells to adapt to the high energy foods.
For maximum endurance, you should not feed your dog the night before going hunting. My Dad told me that 40 years ago and now his advice is documented by real research. This tactic can increase a dog's endurance by up to twice what it would have been if he were fed the night before. In addition, do not feed your dog the morning before going out. The reasons are two-fold: First, the empty gut allows for less straining to defecate, decreases the level of intestinal flopping around in the abdomen, and just makes the dog lighter in weight. Secondly, if a dog eats a big meal, his insulin "spikes" which tends to decrease the animal's ability to mobilize stored fat thus decreasing his energy level.
If you insist on giving your dog an energy snack during the day, pick a high-fat, small volume treat like a hot dog wiener or a piece of that old deer sausage you didn't eat last summer. But, if you do that, keep it minimal and give it to him just before you turn him loose.
Obviously, if you hunting for several days in a row, you have to feed him sometime. I recommend feeding him as soon as possible after you come in from the field or blind. Let him cool off for a while, say 1 hour, then feed him before you go out to eat or to a bar.
All that being said, most hunters want something to give to the dog during a day's hunt or at least at night to give them a "carb boost". After several days of hard hunting, the dog's stored energy (called glycogen) will be decreased, so it is acceptable then to begin some type of daily supplementation. The key ingredient in these type products is maltodextrin, typically mixed in water which you can carry in your vest or blind bag. Pure maltodextrin is available and you can mix about 1/3 cup per 40 pounds bodyweight in about 2 cups of water. This is the gold standard for carb boosting.
One commercially available product that I have personally used and believe in is called K9-Restart made by Tech Mix (www.techmixinc.com). K9Restart in only 10% fat but it does have maltodextrin in it. I have used this product for several years and it is one of the few that I can say that I actually see a difference in the dog's performance. It is cheap and good which is rare nowadays.
While providing extra energy is important, do not overlook the need for hydration. A dog with a dry nose cannot smell as well as one that is well hydrated. The use of electrolytes in dogs is controversial. Some experts think that adding electrolytes may actually increase the level of dehydration while others think that dogs lose some electrolytes in the moist air panted via the respiratory tract.
Bottom Line: Feed correctly and timely. Give your dog some type of energy supplement just before going hunting, i.e. a wiener and maybe give him some K9 Restart as the day progresses.
Feed him as soon as possible after he cools down and provide plenty of water. Keep him healthy and you will be doing all you can do.