I honestly paid very little attention to the hydration products on the market until I was recently asked about them. I am a stickler about water intake though. It is a key nutrient and one that I feel often gets left out when we are talking about other macronutrients such as vitamins, minerals, proteins, fats and carbohydrates. Many of my clients have been told to add water if they feed kibble and in fact I feel everyone should. Water is one of the main nutrient differences between raw meat diets and kibble diets, including grain-free. Whole prey and raw diets contain approximately 70% water while kibble contains only about 10% (yes, kibble does contain some moisture). To me it's no wonder why we see kidney problems in cats when they are fed kibble diets their entire lives. So, those that feed kibble, add a little water to it when you feed.
When I looked up the ingredients on the main products that consumers have access to, I was surprised to see all of them contained maltodextrin as their main ingredient. One of them was very clever and actually "named" their sugar "glucose polymers". One of the company websites even stated directly that "maltodextrin is rapidly absorbed without an insulin release...". Let's stop there for a second. First off, maltodextrin is nothing more than chains of D-glucose units of variable lengths produced from the hydrolysis of starch typically from corn, rice or potatoes. The company is absolutely correct in their statement that maltodextrin is rapidly digested and absorbed. All you need to do is look on the labels of many enteral formulas and you'll see maltodextrin added. The problem I have is the statement that maltodextrin does not produce an insulin release. Comments like those floating around the internet frustrate me. Maltodextrin indeed produces an insulin response just like other sugars in fact it has a higher glycemic index than table sugar, honey, or fructose. I would caution anyone that may have a dog with sensitivities to gluten being that maltodextrins can pose issues for those suffering from Celiac disease. So why start off with a simple carbohydrate as the main ingredient in these formulas?
That answer is based on muscle glycogen recovery research in various animal models including dogs. Dogs involved in high intensity, short duration exercise such as agility or flyball obtain most of their energy from muscle stores through anaerobic metabolism (Cline and Reynolds, 2005; Rovira et al., 2007). So, these products are likely better for muscle recovery rather than "loading" per se, and indeed they indicate that with their product information. Muscle glycogen synthesis post-exercise after depletion occurs in 2 distinct phases. An initial short phase that does not require insulin and lasts 30 - 60 minutes after exercise. The 2nd phase may last several hours after exercise and is insulin dependent. When amino acids and proteins are added to maltodextrin solutions, there is an enhanced insulin response and stimulation of protein anabolism (synthesis). This response is significantly lower when carbohydrate only solutions are used (Jentjens and Jeukendrup, 2003).
The four products I reviewed include: Animal Naturals K9 Go Dog, CPN Power Boost Advanced Rehydration and Energy, CPN Vertex Canine Essentials, and Glyco-Gen Shake. As I did with grain-free products I'm only going to look at the top ingredients in each product.
K9 Go Dogs: Glucose polymers, resistant starch, medium chain triglycerides, beef fat, glutamine, leucine
CPN Power Boost: Maltodextrin, whey protein concentrate, canola oil, medium chain triglyceride, glutamine, lactobacillus
CPN Vertex: Maltodextrin, whole dried egg, whey protein concentrate, poultry liver hydrosylate, canola oil, olive oil
Glyco-Gen Shake: Maltodextrin, whey protein, vanilla
The protein and fat concentration of K9 Go Dog, Power Boost and Vertex are 6 and 9%, 8 and 11% and 24 and 24%, respectively. The fat sources used are very different and range from highly saturated fatty acids (beef fat), monounsaturated fatty acids (canola and olive), medium chain triglycerides (MCT), and omega 3 fatty acids (flaxseed oil). When it comes to dogs (and other carnivores), their efficiency at utilizing fat sources is tremendous. There is little data to support one type over the other; however, I would hypothesize that the beef fat used in K9 Go Dog would make it more palatable than the others but that might be the only advantage (in my opinion). I do like the use of MCT's as they are often digested and absorbed easier than other fats. There are some cases where MCT's have been associated with diarrhea; however, for the vast majority of dogs (and humans) they are digested very well.
Protein sources are primarily whey protein, egg, or free amino acids. All are suitable and highly digestible sources of proteins for this purpose. The amino acid glutamine is listed both for K9 Go Dog and Power Boost. Glutamine is a non-essential amino acid; however, may become conditionally essential particularly after exercise and during periods of protein turnover. It is also a preferred fuel for cells in the gut.
As the ingredient lists continue the products vary in their additions of probiotics (lactobacillus), branched chain amino acids (leucine, isoleucine, valine), alfalfa, algae, and ginseng to name a few. None of the additional ingredients pose any issues or concerns for me, in fact they all likely contribute some nutrition.
A price analysis indicates that per Tablespoon serving (approximately 20 grams) the cost for K9 Go Dog, Power Boost, Vertex, and Glyco-Gen Shake are $0.88, $0.46, $0.40 and $0.63, respectively.
Based on the purpose of replenishing glycogen stores and rehydration after exercise, ingredient lists, and cost, I would choose to use CPN Power Boost. Although I think the Vertex product has a lot to offer in the ingredient list and certainly nothing that would harm, I feel it's just too high in fat and protein to be used as a "rehydration" or recovery product. The product information indicates that it could be used as a daily conditioning supplement and that might be a better purpose for it. It likely would boil down to which product my dogs liked better between K9 Go Dog and Power Boost.
I actually don't use any of these products but I do "rehydrate". I use a mixture of meat-based baby food, honey, and some glutamine mixed with water. I'm sure the inclusion of honey might stimulate more discussion and this post has already gotten long so I'll leave that for further discussion. The thought process; however, is along the lines of these products and my little Keegan loves it.