Gemma Gaitskell
Dr Gemma Gaitskell (BVetMed MSc MRCVS, Royal Veterinary College, London)
Labrador holding an empty bowl in anticipation

A healthy balanced diet providing adequate nutrition is an essential part of looking after a dog. After all ‘we are what we eat’. Deciding between the numerous different diet options and commercially prepared foods can be difficult.

Conscientious dog owners have an ever growing awareness of what is in dog food, with greater access to information via the Internet available to help them make better-informed choices. However, much of this information can be conflicting and or confusing as authors often tend to be strongly in favour of or against certain feeding options.

Basic Nutrition Information

Dog food and water bowls

All foods are made up of nutrients. These nutrients include protein, fats, carbohydrates, vitamins and minerals and water. Dogs require different levels in their diet of each nutrient and these requirements have been carefully studied. Each nutrient plays a vital role in the body, contributing to normal body function and maintaining a healthy weight. Both deficiencies and excesses of nutrients can cause problems so it is important that a healthy equilibrium is achieved to ensure that a dog is happy and healthy.

Although many people do not think water is a nutrient, it forms a very important part of a dogs diet and is essential for the body to function normally. The body requires approximately the same amount of water as it does energy on a daily basis. It is therefore very important that dogs have free access to plenty of fresh water at all times.

In commercially available foods there is often a lot of information on the labels, which if you are unfamiliar with nutrition can be difficult to understand. All nutrients are important but many people focus on the protein content of a diet. The minimum recommended amount for a normal, healthy adult dog is 18% and this goes up to 22% for growing dogs. Fat, although given a lot of bad press in human nutrition is also very important. Relatively small amounts are needed but it plays an essential role in the body, even affecting the immune system.

Vitamins and minerals should also be present in a dog’s diet, although these are usually needed in very small quantities. Their absence or an excess of them can have severe consequences as they are essential for many reactions and functions in the body’s cells.

Different Types of Diet

Jack Russell Terrier chewing a raw meat bone

There are several different types of diet for dogs to choose from, more recently, as with human diets there are certain trends which are becomingly increasingly popular. In the majority of cases, most dogs can eat a normal diet, which contains grain without any problems. Here we have a look at some of the options, along with their advantages and disadvantages.

Commercial Diets

Commercially formulated diets are often available in canned, moist and dry preparations. The category they fall into depends on the water content of the food. When compared to other diet options they can offer some advantages:

  • Nutritionally Balanced (although the reliability of this can vary across brands and qualities)
  • Reduced Variation – These foods are produced to be consistent in terms of ingredients and nutritional value
  • Easy, clean and convenient
  • Less costly

Commercial diets for dogs should be formulated according to recommended minimum nutrient requirements. There are different organisations and government bodies that provide these nutritional guidelines, which can vary slightly between countries. The National Research Council (NRC) first published nutrient requirements in the 1970’s and these are updated every so often. The majority of vets and canine nutritionists feel that using a commercial diet is the best way to provide a dog with a balanced nutrition.

The main reason some owners choose not to feed a commercially formulated diet is due to a lack of control of what their dog is eating in terms of source and quality or a need to avoid certain ingredients – for example, if a dog suffers from an allergy. Otherwise, for most owners, commercial diets are often the most sensible option, providing the most reliable and easy method of giving a dog a complete and balanced nutrition. Commercial diets for dogs can be divided into three broad categories:

Supermarket Foods

This type of commercial diet for dogs is sold in a wide variety of non-specific shops, such as supermarkets, small convenience stores and petrol stations. Although they are generally less costly and may use lower quality ingredients and/or include more artificial preservatives and colourings than premium pet foods or veterinary approved foods, they should still comply with the minimum nutritional requirements for dogs and any regulations set by the body governing dog foods in the country or region where they are sold.

Premium Pet Foods

Premium pet foods are usually of a higher quality than supermarket foods. They tend to be sold by specialised pet shops and are less widely available. They often target a specific ‘life-stage’, breed, size or energy level or use additional beneficial ingredients or recipes.

Life StagesActivity LevelsDog Size
Growth or Puppy Low/Light Mini/Toy
Adult Maintenance Small
Senior Active Medium
Pregnancy/n Working Large

Most foods are available in a variety of meat or fish recipes, some with or without grain, gluten, natural ingredients and a whole other range of different selling points.

Veterinary Approved/Prescription Diets

Veterinary approved diets are also known as prescription diets. This type of diet for dogs is usually sold through a veterinary surgery as they are designed for animals with very specific health issues and are not balanced for a healthy dog. Prescription diets are usually significantly more expensive than other commercial foods, but may form an essential part of treatment for certain health conditions. Feeding a prescription diet is not recommended unless advised by your veterinarian.

Home-Made Diets

Home cooked diets have become increasingly popular over recent years and consist of cooked foods made from scratch at home following different recipes. It is very important that the diet is designed so that it provides a balanced nutrition for the dog in question and is supplemented with the correct balance of vitamins and minerals, as inadequately balanced diets can be a major problem with this choice of diet for dogs. Read more about home cooked diets.

Raw Diets

A trend towards recreating the type of diet a dog may have eaten in the wild has seen raw diet options grow in popularity in recent years. As the name suggests raw meats and bones, sometimes in addition to some other raw foods, are fed in this kind of diet. Although there are strong supporters of this kind of diet, unfortunately, there is a lack of solid scientific evidence that backs up the benefits, and the cons outweigh the pros. Due to this, most veterinary bodies do not support the feeding of this kind of diet. Read more about raw diets.

Feeding Your Dog

Feeding a Jack Russell Terrier kibble

The amount you need to feed your dog depends on several factors. These include things such as age, activity level and whether he or she is growing, but the energy level found in a food should also be taken into account.

Most commercially available diets provide a rough guide on the packaging to give an indication of how much is needed. However, these guidelines tend to provide a fairly broad categorisation, so it is more than likely you will need to adapt these to the needs of your dog.

Energy Requirements

A dog's energy requirements depend on life stage and activity level in addition to individual variations in metabolism and environmental temperature. Energy is derived from the different nutrients that are contained in a food, such as protein, fat and carbohydrates. The amount of energy in a diet is also affected by its digestibility; this is the amount of energy that is actually available to a dog from a food. The energy in a diet is usually displayed in the form of calories on the label.

Muscle has a higher energy requirement than fat, so dogs that are overweight have lower energy requirements. Activity level is the principal factor which influences how much energy a dog needs, and as many dogs are relatively inactive this should be taken into account, with the amount they are fed being limited accordingly. If a dog has an insufficient energy intake in their diet this can also cause consequences, such as poor growth and weight loss.

A Brief Look at Pet Food Labels

Understanding pet food labels and whether certain ingredients which get negative press are actually ‘bad’ for your dog can be difficult and confusing. Certain ingredients, for example, "by-products" have received a poor reputation. By-products are often perfectly acceptable and nutritious ingredients that are simply unwanted in the human food production chain, often because of their appearance. Many meat by-products include organs and bone and can often be higher in some essential vitamins and minerals than the meat itself.

Grain is also an ingredient that has recently got a lot of poor press. It is in fact a perfectly acceptable source of carbohydrate and other nutrients. Dogs are omnivores and therefore need some source of carbohydrate in their diet. Studies have also shown they are perfectly able to digest the starch found in grains. Many foods claim to be ‘grain-free’ as a selling point, but unless your dog is suffering from an allergy to grain or gluten (a protein found in some types of grain) then there is no reason why you should necessarily avoid them.

In addition, commercial foods should contain adequate levels of the major nutrients and meet the minimum requirements of the body which is responsible for regulating them in the country where they are sold. Most foods will state whether they comply with regulations and any testing they put foods through on the label.

Changing Your Dog’s Diet

Any planned change in diet should be implemented over a number of days, as gradually as possible. The time you take to introduce a new type of food may depend on how sensitive your dog is to different types of food. A dog with a very sensitive stomach may require a longer period with a more gradual diet change, but a typical plan to change from one food to another would be over 5-7 days. Whilst we provide an example below, it is always best protocol to consult with your local veterinarian before changing your dog's food, as each dog is different and may require a different changeover plan:

  • First Day – 10% new food, 90% old food
  • Second Day – 20% new food, 80% old food
  • Third Day – 30% new food, 70% old food
  • Fourth Day – 40% new food, 60% old food
  • Fifth Day – 60% new food, 40% old food
  • Sixth Day – 80% new food, 20% old food
  • Seventh Day – 100% new food

When introducing a new food to a dogs diet you should keep an eye out for any digestive upset, such as vomiting and diarrhoea. If you are introducing a new food slowly, following an appropriate plan and your dog suffers from vomiting or diarrhoea, it is wise to return to the old food and consult your vet, especially if this occurs more than once.

There are occasions when a sudden diet change may be necessary for a health related reason. These are often conditions that will have been diagnosed by your vet, who will have recommended the diet change. Some examples of health issues which may cause your vet to advise a sudden change in diet include:

  • Food allergies
  • Liver and kidney problems
  • Digestive upsets
  • Urinary problems
  • Diabetes


Deciding what type of diet you are going to feed your dog can be a tough choice, especially given the numerous different options and often conflicting information available about them. As with most things, you generally get what you pay for. A very cheap dog food is likely to use lower quality ingredients as high quality ingredients are expensive and it is therefore not feasible to expect that an economy food will contain the best.

Despite this, it does not necessarily mean that you need to buy the most expensive food available. There are many good middle range options and learning some basics about nutrition and what to look out for can help you make a better-informed choice. If you are ever unsure what diet to feed your dog, your local veterinarian will be willing to help you make a decision or explain anything that you do not understand.