Fats and Proteins and Carbs, Oh My!
When it comes to diet, dogs are carnivores. Specifically, they are what are known as facultative carnivores. This means that although they can gain nutrients from some vegetable matter, their digestive system is better equipped to handle animal products such as meat.
According to the National Research Council (NRC), Dogs are able to obtain all the nutrients they need from raw fat and protein. The reason for this is that a dog’s digestive system evolved primarily to process wild prey. Unlike us, dogs never evolved to produce the enzyme amylase in their saliva, however, they do produce a small amount in their pancreas, meaning they are able to digest a small amount of plant matter. This has a significant impact on what makes for a healthy diet for any dog and should be considered when providing for your best friend’s nutritional needs.
The National Research Council generates species-specific reports that serve as the authoritative source of state-of-the-art recommendations for meeting the nutrient requirements of various animal species. In their 1986 publication of The Nutrient Requirements of Dogs, the NRC stated that as per two studies done by Brambila and Hill (1966) and Belo., et al (1976), dogs did not require any carbohydrates – plant matter – to be included in their diet in order to thrive. This has remained unchanged in their most recent publication, The Nutrient Requirements of Dogs and Cats (2006). While humans are able to utilise carbohydrates exclusively as an energy source, dogs obtain the bulk of their energy from protein and animal fat. For dogs, the digestibility of fat is between 85% and 100% depending on the source and quality. The digestibility of carbohydrates on the other hand range between 0% to a maximum 55%. In addition, FEDIAF – the trade body representing the European pet food industry makes no mention of carbohydrate content at all for either dogs or cats.
What this means is that while you certainly can feed your dog a plant-based diet, a meat-based diet will always be healthier for them. Pound for pound, a dog will better digest – and thus get more energy – from meat-based diets.
The Role of Fat, Protein and Carbohydrates in Dogs
Fat has numerous roles within the body; it’s the body’s primary form of stored energy, it protects vital organs from injury, insulates the body preventing heat loss and helps the skin guard against penetration of foreign substances. One gram of fat contains twice the energy of one gram of protein or carbohydrate. Fat is also vital for brain function, it surrounds nerve fibres and aids in the transmission of nerve impulses. Omega-3 fats are essential for learning and memory function. Several fat-derived compounds perform extensive hormone-like actions in the body and are involved in vasodilation and vasoconstriction, muscle contraction, maintaining blood pressure, gastric acid secretion, regulation of body temperature and blood clotting. The gross energy of fat is 9.4 calories per gram, while protein and carbohydrate offer 5.65 cal/g and 4.15 cal/g respectively.
Why Do Dogs Need Protein?
Proteins are the literal building blocks of life. They are used to build muscle, skin, bones, ligaments and even hormones. Proteins are made up of amino acids, most of which are able to be made by the body, however, there are ten amino acids that are essential to a dog’s health that must be obtained through food. These are Arginine, Methionine, Histidine, Phenylalanine, Isoleucine, Threonine, Leucine, Tryptophan, Lysine and Valine. Taurine is an essential amino acid that cats require, however, unless your dog’s diet is consistently high in legumes (think grain-free dry food), it is not viewed as an essential dietary requirement.
Why Dogs Need Carbohydrates
In the body, carbohydrates have several functions. A constant supply of glucose is necessary for the proper functioning of the central nervous system, glycogen present in the heart muscle is an important emergency source of energy for the heart. Carbohydrates also supply carbon skeletons for the formation of non-essential amino acids and is needed for the synthesis of other essential body compounds such as glucuronic acid, heparin, chondroitin sulphate, the immuno-polysaccharides, DNA and RNA. Digestible carbohydrates also have a protein-sparing effect. When an animal eats, the body satisfies its energy requirements first before using the energy-containing nutrients in the diet for other purposes. If adequate carbohydrates are supplied in the diet, protein will be spared from being used for energy and can then be used for tissue repair and growth.
The 3 Forms of Carbohydrates
Carbohydrates come in three forms; sugar, starch and fibre. The simplest carbohydrates are monosaccharides and disaccharides, more commonly referred to as sugars, that are found in many refined grains like white rice, fruit (fructose) and dairy products (lactose). These sugars are quickly and easily metabolised providing short-term energy.
Complex carbohydrates such as starch and fibre are made up of larger, and more complex molecules called polysaccharides. Both soluble and insoluble fibres are only found in unprocessed whole plant foods such as vegetables. Complex carbohydrates provide a slower released energy, aiding in digestion, helping to maintain the immune and nervous systems and will help regulate the metabolism.
Glucose is the form of carbohydrate found circulating in the bloodstream and is the primary carbohydrate used by cells for energy. It is the final product of starch digestion and glycogen hydrolysis.
When glucose is detected in the body, the pancreas secretes insulin into the bloodstream to regulate blood sugar levels. Insulin instructs the muscles, cells and fat tissues to absorb excess glucose, however, the body can only store so much. When there is an excess, it is turned into glycogen and stored in the liver for later usage. Once the liver has reached capacity, glycogen is further converted into fatty acids and stored in the tissues as fat.
Although dogs have a very limited capacity to store carbohydrates in the form of glycogen, they have an almost limitless capacity to store surplus energy in the form of fat. This means that eating more carbohydrates than the bodily energy requirements will lead to increased body fat and obesity.
What this means for your dog
Every dog is different. However, if your dog is energetic, playful, and gets lots of exercise, then it will need a high-energy diet. But that doesn’t just mean feeding it meat unconditionally. Although it is often the best for them, there are things to consider. Additionally, you may also have noticed that many commercial dog foods recommended for a dog’s health are also predominantly plant-based. Let’s take some time to consider the limits of raw food and the reasons behind the commercial variants.
Periods of high energy demand in dogs occur during growth, gestation, lactation and prolonged periods of physical exercise. Feeding an energy-dense, high-fat diet during these times can allow a dog to consume adequate calories without having to ingest excessive amounts of food. In addition, feeding a diet containing a sufficient concentration of dietary fat during strenuous physical work has metabolic benefits. Fatty acids are the primary source of energy used by the body during prolonged physical exertion. Studies of dogs engaging in endurance events such as long-distance sled races have found that the consumption of a high-fat diet enhances dogs’ ability to use fatty acids for energy which can ultimately contribute to improved performance.
Dogs & High Fat Foods
Feeding high-fat energy-dense foods during periods of rapid growth must be strictly monitored. This is especially important for large and giant breeds of dogs as high-fat, energy-dense foods that are balanced for all essential nutrients are capable of supporting a high rate of growth if they are fed ad-lib. The maximal growth rate has been shown to be incompatible with proper skeletal development in dogs and is a risk factor for the development of several skeletal disorders.
Excessive fat intake can also be detrimental to a pet’s health. Providing more fat than the gastrointestinal tract can effectively digest and absorb results in fatty stools and diarrhoea. This problem is commonly observed when pet owners provide their dogs with table scraps composed predominantly of fatty foods. Any fat to be given must be raw and of high quality, once the fat is heated it becomes rancid and can quickly lead to life-threatening conditions if fed in large quantities.
So why are carbohydrates a large percentage of commercial food? Typically, this is because carbohydrates provide a certain amount of structure and texture to their meals and they are much cheaper than meat. It’s also more convenient and cost-effective to add synthetic nutrients to a carbohydrate-based diet in order to meet the minimum RDIs than it is to prepare a whole-food diet on a commercial scale.
Whilst I advocate for raw feeding, everyone’s circumstances, situations and dogs are different. Ultimately, you should feed the best complete diet you can afford and more importantly, what keeps your individual dog fit, healthy and happy.
