There are many sports that we can practice with our dogs. Even if most of those sports are only practiced on amateur basis, it is possible that your passion brings you and your dog on a more professional level. At this level, small details will make a difference, like the muscle strength and the endurance of your dog compared to others. Like for human athletes, there is a lot of ways to help your dog to perform better, with targeted training and diet, but that’s where the resemblance stops. Indeed, as it will be discussed below, dog metabolism is very different from us, and the adjustment in their diet to promote stamina and muscle growth are very different than us.
The main difference relies on the type of muscular fiber than the dogs have, that are different from us and even from cats. Understanding how those muscular fiber works, what are their purpose and how they prefer to get their energy will help us understand what type of diet should be fed and when. Without going in too much anatomic details, it is important to know that there are three types of skeletal muscle fiber (muscle used for locomotion). They are varying in proportion depending on the species, and some species like dogs only have two of the three fiber type. Those fibers are classified depending on what are their preferred way of creating ATP – the fueled for muscles. The first fiber type prefers the use of oxygen to create energy (aerobic), the second type can create energy with or without oxygen (aerobic and anaerobic), and the third type is more efficient in creating energy when there is no oxygen available (anaerobic). The first two type of fiber can use carbs (glucose), fat and protein as their source of energy, when the third type strictly use what is called a glycolytic pathway – it can only use glucose as its energy source.
Dogs do not have this third fiber type, and this is one of the major differences they have with us. That means all their muscle fibers has strong aerobic capacity, and that will have a major impact in what type of energy source will be preferred by their metabolism. Aerobic muscle fiber use mainly fat has their energy precursor, while anaerobic muscle use glycogen. Aerobic muscles are for endurance, and anaerobic muscles contract faster and stronger, but fatigue more easily.
Before going deeper into what muscle use what energy source, when and why, let’s talk about those energy source. I’m sure that just like many others, glycerol, glycogen, glucose, etc. all sounds the same to you.
Back to the start, there is three major nutrients that dogs (and us) eat and that can act as energy source to the body: carbohydrates (glucose), fat and protein. There is a wide variety of each of these nutrients, and they will be stock in the body in different forms. The body will stock fat as fat, protein as protein or fat, but will not stock carbs as carbs. Carbs will be transformed primarily in glycogen to be able to stock them in glucose form, and the extra carbs will be stock as fat – this regulation role is mainly done by the Insulin. The body stock carbs in glycogen as a fast energy source – we can find glycogen mainly stocked in the liver, and some in muscles. But glycogen storage capacity is quite small, compared to fat storage capacity. When all the glycogen storage are full, the extra glucose is stored as fat for long-term-use energy source.
When there is a high energy demand, the body will that to break down glycogen to create the fueled – ATP. Once all the glycogen is gone, the body switch to alternative source of energy. In the human body, this is 100% true. What is also true is that if you are able to build and promote glycogen storage or provide glucose during a physical exercise, you will increase your stamina capacity. If there is more glycogen available for a longer period, your muscles will be able to rely longer on this energy source. Science have shown that it is not the case in dogs.
Now back to the energy storage, how does the body use fat and protein as the energy source, instead of glycogen? When the body needs energy, the signals also go into the fat storage, and the protein storage. To become a source of energy, proteins will be broken down in amino acids and converted to glucose by the liver. Not all amino acids can be converted to glucose – alanine and glutamine are the preferred ones. When energy is created from glucose, either from the glycogen storage or protein storage, it is called the glucogenic pathway.
The signal will also go into the fat storage. That will induce the break down the fat into two components: free fatty acids and glycerol. Those two components will then travel to the place where the energy is required and will be able to create ATP as well. The metabolic pathway for the creation of energy from free fatty acids and glycerol is called ketogenic pathway, and requires oxygen, while energy create from glycogen – glucogenic pathway – can be done anaerobically. Fun fact, fat oxidation can create 3x more energy than glucose oxidation. Some protein can also be involved in the ketogenic pathway instead of fat, and the two preferred amino acids for this energy conversion are leucine and lysine.
Glycogen is used by anaerobic muscle for a fast and strong contraction, but since the storage of glycogen is limited, those muscle will also lose their energy source faster. Those muscles are involved in sprint and jumps, but less in endurance exercises, while aerobic muscle can rely on long term energy storage like fat or protein. They will be slower to get on but will be able to work for a long period of time.
It is very important to understand all those energy conversion process, because it will guide us in the elaboration of a diet for your little furry athlete. We could go even deeper into those metabolic pathways, but you understand enough now for the purpose of this article. Here’s what there is to remember:
Carbs that the body will eat is going be stored in glycogen, while the extra will be stored as fat. Glycogen is the fastest energy source, but the storage is limited. Fat and protein will be stored as they are and are efficient and long-term energy source to use by endurance muscles.
There are some very important differences between dogs and humans that we need to take in account. Based on the information provided above, it would be logical to think that dogs will also use all the glycogen available before jumping on fat and protein as energy sources, and that building glycogen reserve is a great way to increase the body stamina. That would be forgetting that the main muscle fibers in dogs are aerobic fiber, and therefore, dogs are naturally more adapted to use protein and fat as energy source. Studies have shown that at rest, muscle use aerobic energy source, 20% from free fatty acids and 30% from glucose. When the dog has to do a physical effort, the proportion of glucose utilization will decrease to 10% and the free fatty acids proportion will rise up to 70% of the energy source. Those proportion will change with the intensity of the physical effort. If the dog is closer to maximal effort on a short period of time, the utilization of glucose (from glycogen or protein) will increase at the detriment of fat, but still on the aerobic pathway. During physical exercises, dogs will rely on anaerobic source of energy for the first 7 to 15 seconds of effort and will then move to aerobic energy source after 30 to 60 seconds of effort, even if there is still glycogen available. This is why, in opposition of human metabolism, high fat, high protein and low carbohydrate diet is more likely to build stamina in dogs. Glycogen storage only has an impact on anaerobic energy source, while dogs rely faster of aerobic energy source during a physical effort. There is therefore no benefit to dogs of feeding high carbs diet in the purpose to potentially increase glycogen storage and stamina. Feeding higher fat diet has been proven to spare glycogen storage and improve stamina.
Higher carbs diet (over 38% carbs) have also shown to lower the concentration of red cells in blood. Red cells being the oxygen transporter, high carbs diet also have an impact on stamina because of this. If there is less oxygen arriving to aerobic muscle, the energy conversion slow down. There are also studies that have shown that very active dogs such as sled dogs can rely 100% on protein has their glucose precursor. The liver will convert certain amino acids in glucose which will be store as glycogen and it will be available for anaerobic energy source for short intense physical effort.
All that being said, it doesn’t mean that your dog can’t benefit from some carbs in their diet, but the amount and the time of feeding is important. Also, and more importantly, carbs shouldn’t be added in the detriment of protein and fat, but it could help for sprinter dogs or dogs having a hard time building fat storage on protein and fat diet only. For dogs doing sprint or acceleration only, a maximal effort during a short period of time, here’s what the diet breakdown should look like: minimum 30% of metabolizable energy coming from fat, minimum 24% coming from protein, and maximum 45% coming from carbs. For other sport dog, like hunting, traction or any sport involving more aerobic energy source, the diet breakdown should be: minimum 50% of the metabolizable energy coming from fat, minimum 35% coming from protein, and maximum 15% coming from carbs.
To calculate how much calories comes from which nutrient, you simply need a guaranteed analysis of your dog’s diet and remember those easy numbers: each grams of fat brings roughly 9kcal, each grams of protein 4kcal, and each grams of carbs (excluding fiber) 4kcal. Multiply those number by the % of each nutrient, and divide by the total kcal per 100g, and you will have the proportion of energy coming from each nutrient.
As an example, a typical raw food containing 17% protein, 11% fat, 4% carbs, 65% moisture and 180kcal per 100g will have 38% calories coming from protein, 55% from fat and 8% from carbs. As you can see, this raw diet you be very suitable for dogs doing more endurance exercises. If we now take a typical “high quality” kibble analysis, being 30% protein, 16% fat, 34% carbs, 10% moisture and 470kcal per 100g of food, the breakdown would be 26% kcal coming from protein, 30% coming from fat and 30% coming from carbs. This food would be less adapted for endurance sport, and maybe more for dogs doing short and intense sprints as their physical exercise. It doesn’t mean that if you dog eats a high carbs food that he can’t practice any dog sports, it just means that you are not promoting high stamina and maybe higher overall performance. Since we now know that protein can be stored as glycogen as well, it might be a better strategy to rely on higher protein diet if you have to feed a lower fat content protein, instead of increasing carbs.
We also need to keep in mind that body score condition and overweight can play a major role in sport performance. Overweight increase the risk of injuries and joint issues. Science now shows that obesity is mainly linked to high sugar diet (glucose and starch) – eating a lot of those carbs increase the secretion of insulin, that increase the storage of glucose in fat and decrease the effect of leptin, the satiety hormones. It is called leptin resistance and brings the body in a never-ending circle of being hungry and stocking fat. Feeding a low carbs diet to canine athlete therefor promote stamina and reduce the risk of overweight.
As we discussed earlier, you can also choose the type of protein to feed based on their amino acids profile. Alanine and glutamine will support the glycogenic pathways, while leucine and lysine will promote the ketogenic pathways. There are other amino acids than can be useful to canine athlete, like creatinine and carnitine. Those two amino acids are in the non-essential categories, meaning the dogs are able to synthesize them with the help of other amino acids, but some research have shown in human nutrition that they can promote the energy transport to muscle and muscle recovery. There are no studies in dogs that are showing the same results, but it is safe to assume that feeding meat that are naturally higher in those amino acids can’t hurt.
Here’s the list of Big Country Raw recipes, their % of calories from each nutrient, listed in order of alanine, glutamine, creatine and carnitine concentration per 100g. You can modify the meal rotation of your dog to favor those meals during high exercises periods, during trials or intense training period. If you are mainly feeding kibble and want to introduce some raw food to promote your canine’s performance (reduce carbs and increase protein and fat ratio), you can also use this list of products to help you chose which meal to give to your dog for the specific purpose of improve performance. As you can see, red meats are always a good indicative of the higher amount of these amino acids.