An animal eats to provide itself with energy. Food provides the fuel required to keep the body functioning properly. The quality of the food eaten therefore has a direct impact on the overall health of the animal and on its energy levels. If we want a dog to be as healthy as possible, we need to ensure that its diet contains high quality ingredients to provide all the nutrients and energy he needs on a daily basis.
Dogs require a variety of different types of nutrients. These include proteins, fats, carbohydrates, vitamins, minerals and water. Nutrients are classified in two ways, essential or non-essential nutrients. Essential nutrients are those nutrients that are needed but cannot be synthesised by the body. They must therefore be contained in the dog’s diet. Non-essential nutrients can be synthesised in the body from other nutrients so do not necessarily have to be included in the diet.
Below you will find a summary of the different nutrients required in order for a dog to remain healthy. All dogs, no matter what their age or lifestyle, need a combination of all these nutrients However, the required concentration of each nutrient will change as the dog progresses through his life. When choosing a diet for a dog, it is therefore important to consider his age, his breed size and also his lifestyle.
For example, a puppy will need a more energy- and nutrient-dense diet to support his fast rate of growth. He will also need a diet with an optimal level of DHA to support optimal brain development. A nine year old dog on the other hand, will need a diet with higher protein levels than that of an adult dog (to maintain muscle mass) but with reduced fat levels (to manage his weight as his activity declines).
In summary, we need to consider the following elements when choosing a food for our dog.
Proteins perform many important functions within a dog’s body: they are used to build tissues (e.g. muscles), to protect against infection and to transport oxygen, vitamins and hormones in the blood. They can also be used as source of energy (however, in a correctly balanced diet the majority of the dog’s energy will not come from protein but from carbohydrate and fat).
The quality of different individual protein sources varies a great deal, depending on both the amino acid profile of the protein and on its digestibility. One measure of the quality of a protein is called the ‘biological value’, which gives an indication of the nutritional value of the protein that is actually retained and used by the body. The greater the biological value, the better. For a dog, animal proteins have a much higher biological value than vegetable proteins. In particular, egg has the highest biological value, followed closely by chicken, lamb and fish.
The best diet for a dog is therefore one in which the protein comes from animal rather than vegetable sources. There is no fixed optimal percentage of protein needed in dog food as the amount required depends on both the quality of the protein source and on the energy content supplied by other nutrients within the food.
Fats (along with carbohydrates) are the primary sources of energy for the dog. Fat is the most energy-dense nutrient, containing more than twice the energy of carbohydrate and protein. As well as being a source of energy, fats also have other important functions. They are the building blocks for hormones, they help transport fat-soluble vitamins and they are a source of essential fatty acids. In particular, studies have shown that fatty acids omega 6 and omega 3 are critical to skin and coat health and that the optimal ratio between these two fatty acids is 5-10:1.
Carbohydrates exist in two forms: digestible and non-digestible.
Digestible carbohydrates, also know as starches, serve as a source of energy. Examples of starchy foods are grains such as wheat and barley.
Non-digestible carbohydrates, also known as fibre, help to transport foods in the digestive tract but if added in large amounts can interfere with the absorption of nutrients by the body. Examples of fibre are bran, cellulose, beet pulp and hulls.
Fibre also has the important function of nourishing the intestinal cells and therefore supporting gut health. Some fibres are fermented more quickly and easily in the gut than others. It has been shown that a moderately fermentable fibre source (such as beet pulp) is optimal for promoting the intestinal health of the dog. This is because it provides the optimal energy for the cells lining the intestine through the production of short chain fatty acids whilst also providing bulk to move waste through the system efficiently. If the fibre is poorly fermentable, it does not provide sufficient short chain fatty acids so the intestine appears under-nourished. It can also result in dry stools and constipation. If the fibre is too highly fermentable it can increase the frequency of the stools and decrease the absorption if nutrients.
Most vitamins needed by dogs must be provided in the diet as they cannot be synthesised in the body. Vitamins are either water-soluble (i.e. they are carried by the water in the body) or fat-soluble. Vitamins C and B are water-soluble whereas vitamins A, D, E and K are all fat-soluble. Provision of each individual vitamin is critical to the health of the dog as they each have a different function within the body. For example, they promote proper healing and tissue repair, they promote cell growth and development and they enhance metabolic reactions.
The most important minerals required by dogs in their diet are calcium, phosphorous and magnesium. These minerals help to maintain fluid balance, they help with muscle contraction and are building blocks of the skeleton itself. The percentage of minerals required in the diet depends on its energy content. There are also minerals, called polyphosphates, which have been shown to reduce tartar build-up on the teeth. When the dog bites on the kibble, the polyphosphates are released to embed themselves in the plaque on the teeth to block tartar build-up.
Water is the most important nutrient as it makes up 60-70% of the body. It is a component of blood, cells and the lymph system. It is involved in every body process including helping to regulate the body temperature and to dissolve and transport materials through the body.