Cat and Dog Pet Food Guide

Choosing the right pet food for your cat or dog is important both for their health and well-being, and also your finances, but with so many different cat and dog foods available how do you pick which is best? Good nutrition helps your pet maintain a luxurious skin and coat, strong muscles, bones and joints, and helps them stay healthy, so it's worth spending some time looking into what they are eating so you can provide them with a food that best meets their needs, but is affordable too.

We've put together some information to help you decide, although no single food is best for every animal so you may need to try several to determine which is best for your particular pet. Any good quality complete pet food from one of the well-known manufacturers should provide your pet with their basic nutritional needs, although the wide range of foods available mean there are foods designed to meet your pet's specific needs - for example, "light" foods provide less calories, so can avoid weight gain in less-active pets.

If your pet has specific dietary needs, or you are still unsure about which pet food to feed your pet, then do seek professional advice from your vet.

What's in Pet Food

Pet Food Ingredients

Foods are made up of three main components: Carbohydrates, Fat and Protein, plus vitamins and minerals.


Carbohydrates are important as they provide a readily available energy source. They can be divided into three categories: sugar, starch and fibre, however when people talk about 'carbs', they are typically talking about sugars (like fructose and glucose) and starches (like flour), as fibre is not digestible by cats, dogs and people.

Carbohydrates are not considered essential nutrients, however they do serve many important purposes such as providing energy, and starch provides the necessary structure to help achieve different shapes, textures and densities of kibble which is important as different animals have different preferences and requirements for dry food.

Adding or removing Carbohydrates from the food also enables the amount of energy provided by fats and proteins to be adjusted, which is important for animals with particular dietary requirements such as low fat diets.

Carbohydrates can be obtained from numerous sources, such as grains, fruits, legumes and vegetables.


Fibre is the part of plants that can't be digested, and as a result it doesn't provide any calories and passes through the digestive system virtually unchanged. Along the way however it does provide some useful functions.

Fibre absorbs water like a sponge, so if there is excess water in the colon (for example if your pet is suffering from diarrhoea), the fibre will help soak it up which results in a firmer stool. It also helps when the opposite is true and there is too little water which results in constipation, as the fibre will draw water in from surrounding tissues.

Fibre also slows down the digestion of the other foods it is consumed with, which is useful for helping with weight loss, as the slower digestion means your pet will feel fuller for longer. It is also useful if your pet suffers from diabetes, as the fibre helps to provide a slow, steady release of dietary sugar into the bloodstream.

Fibre is only found in plants, so almost all grains and vegetables contain fibre, however meat doesn't contain any.


Fats (or oils) are a concentrated source of energy, and are important as they supply building blocks for the growth of tissues in the body, and are essential for healthy skin and hair. They are classified as saturated, unsaturated, or polyunsaturated according to their structure, and all three fat types share some common functions, but unsaturated and polyunsaturated fates have additional features that are beneficial to your pet's health.

Fat soluble vitamins (vitamin A, D, E, K) require fat to be present in order to be absorbed, and fat is often a source of these vitamins as well. In addition, fat influences the smell, flavour, texture, and moisture level of foods, which contributes greatly to how palatable the food is. Common nutritious oil supplements include fish oils, Borage oil, Evening Primrose oil and Rosemary oil.

While fats are essential and many can be beneficial, others can be harmful and too much of any fat can lead to your pet becoming over-weight, and suffering from related health problems. Many pet food manufacturers add large amounts of low grade, highly processed fats (usually just referred to as 'animal fats' or 'oils and fats') to make the food taste better, however these fats tend to contain large amounts of saturated fats which can raise blood cholesterol and may contribute to heart disease.

If your pet is overweight, you should look for foods that contain lower than average amounts of fat. For example, dry dog foods contain around 9-14% fat (about 2-4% for wet foods), however If your dog is overweight, you should look for foods with less than 10% fat (2.5% wet).


Proteins plays an essential role in almost every aspect of the body; including muscle tissue, the immune system, bones, blood, and within cells of the body. Protein can be used as a source of energy, however when carbohydrates are present in the diet, they will provide energy which allows the protein and fat in the diet to be used as building blocks for the production and maintenance of body tissues, instead of being used as an energy source.

Proteins can come from many sources, and while the most natural and digestible form comes from meat and fish, grains, seeds, legumes and vegetables are also good sources of protein.

Unfortunately, meat is an expensive ingredient and the manufacturers of many cheaper pet foods substitute meat with cheaper protein sources like soya meal, maize, potato protein and vegetable protein. Proteins from non-meat sources are harder for your pet's body to digest and use and have a higher chance of causing dietary intolerance. Just like many things in life, when it comes to protein, go for quality rather than quantity.

Omega-3 and Omega-6

Omega-3 and Omega-6 fatty acids are considered to be essential as they cannot be made by the animal, so must be obtained from food. Omega-3 and Omega-6 are beneficial to neurological development, the immune system and managing inflammation, and also play a vital role in improving skin and coat health. It is important however to balance the amount of Omega-6 and Omega-3 fatty acids in the diet, as too much Omega-6 can be detrimental to your pet's health. The ratio should be around the 1:1 to 5:1 ratio (i.e., up to 5 parts Omega-6 to 1 part Omega-3). In general, foods containing meat from animals that eat grass will contain more Omega-3 than foods containing meat from grain-fed animals.

Essential and Non-Essential Amino Acids

Amino acids are are organic compounds that are the building blocks of protein, and there are two types of amino acids - essential and non-essential. Essential amino acids cannot be manufactured in the body in sufficient quantities (if at all), so they must come from the food. Non-essential amino acids are just as important as essential amino acids, however, the body has the capacity to manufacture them in sufficient quantities. Cats require 11 essential amino acids, while dogs need 10.

One example of an essential amino acid is Taurine, which is vitally important for a cat's heart muscle function, vision and reproduction, but cats bodies can't manufacture it in sufficient quantities so it has to be included as part of their diet. Taurine is found naturally in muscle meat and seafood, so cat foods with high levels of good quality natural meat ingredients doesn't require additional Taurine to be added, thus it won't be listed as an additional ingredient.


Despite what some people think, the ash content of pet food is not the same stuff that you find in a fireplace. It actually refers to the mineral content (e.g., calcium, zinc, iron, etc...) of a food that remains if the food was incinerated, and all the carbohydrates, fat and proteins are burnt off. Animals require a variety of minerals to stay healthy, so this figure isn't particularly important for most pet owners. However animals with kidney or urinary problems will benefit from a lower ash content, and growing kittens and puppies will require sufficient minerals to ensure healthy bone growth so look for a relatively high ash content.

Why are some foods more expensive than others?

Cheap and Expensive Pet Food

As with most things in life, you tend to get what you pay for and this is certainly true for pet food.

"Supermarket" and Economy Food

The more economical foods tend to contain lower-quality ingredients that are cheaper, but less easy to digest. While less expensive, these foods don't usually provide your pet with the healthiest and nutritious ingredients, so are less beneficial than some of the higher-quality foods. The energy levels may be lower, proteins are from lower-grade sources thus less easy to digest, and they are more likely to cause food intolerances.

Premium Food

These foods are more expensive than the economical versions and contain higher quality ingredients, but still may contain some of the same ingredients as the cheaper ranges including artificial colours and flavourings. The protein sources will usually be higher quality than the cheaper foods, so these foods will be easier for your pet to digest, and more beneficial to their health.

Healthy Foods

These foods contain high quality protein sources like real meat, poultry or fish (NOT meat by-products), and also carbohydrates from whole grains like whole rice, oats and barley to provide high energy levels. These will also include fibre from vegetable sources like potatoes to help maintain healthy digestion.

Vegetables and fruits such as apples, carrots, and cranberries provide natural sources of the essential nutrients, and sunflower and fish oils will provide energy and help maintain healthy skin and coat.

Complete or Complimentary Food

The difference between "Complete" and "Complimentary" pet food is that foods that are listed as being complete contain all the ingredients your pet requires, and require no additional supplements. Complimentary food, such as snacks, and some purely fish or meat-based foods, are not nutritionally balanced on their own, should always be fed in addition to your pet's main meal.

Cat Food

Cats are obligate (or 'true') carnivores, which means their digestive systems have adapted to a strictly carnivorous diet, and they have difficulty in digesting carbohydrates. In the wild, cats naturally choose high quality, high protein foods, and while they may consume small amounts of plant material, they appear to be unable to absorb certain essential nutrients from vegetable matter, and so they rely on animal protein to supply these elements. As meat contains no carbohydrates, and cereals are high in carbohydrates it's important to look for cat foods that have a high meat content, and little or no cereal ingredients.

The quality of the protein is important too, and real meat, poultry, fish and egg are all considered superior to by-product or grain sources as they are more easily digested.

Kittens and senior cats have different nutritional requirements to adult cats, so make sure you select a suitable food for your cat's age. The same applies for cats who are under or overweight, or those with certain medical conditions like diabetes or allergies. In these cases, you should consult your vet for advice about selecting the appropriate food for your cat's condition.

Cats are individuals, and often have their own preferences for food so it can take a bit of trial and error to find a food that they will eat, whether it be wet or dry, meat or fish or even the flavours that they prefer.

Wet or Dry Cat Food

Typically, wet foods are considered better for cats as the higher water content helps prevent kidney and urinary tract problems. In the wild, cats obtain most of their moisture from the animals they hunt (their typical prey consists of around 70% water), and most wet food contains around 80% moisture, compared to just 10% for dried food. If you do feed your cat a mainly dry-food diet, it's important to make sure that they have access to plenty of water too - ideally in a location away from their food, as cats prefer their food and water sources to be apart. A water fountain can work well to encourage the cat to drink.

Dog Food

Like us, dogs are omnivores and are capable of digesting a wide range of foods, however unlike us their digestive system is much more geared-up for meat consumption, so they benefit from a diet rich in meat.

Small breeds

Small breed dogs tend to have a faster metabolism than larger dogs, which means they will usually benefit from higher energy foods. Many dog food manufacturers produce specific small breed diets, but where they are not available, puppy foods can provide a good alternative as they are high in energy, and the dry puppy foods have smaller biscuit sizes which smaller dogs prefer.

Large breeds

Larger breeds mature later, and often don't reach full size until 15-18 months of age, but then they tend to reach old age much faster, with the average life span of many giant breeds being only 6 or 7 years. The majority of large breed foods contain extra supplements like Chondroitin and Glucosamine to help the joints cope with the greater weight of the larger dog.

Senior dogs

Like us, as adult dogs get older, their metabolism slows down and they require less energy from their food. Food that is specific to senior dogs contains fewer calories, but normal adult dog food is also fine in smaller quantities. Senior diets do however allow for certain supplements to be added to help with common problems that older dogs suffer, for example joint problems.

Glossary of Pet Food Ingredients

Animal FatUsually a by-product of meat meal production. Specific named fats (e.g., Chicken Fat) are better than non-specific as "animal fat" could refer to any fat from any animal.
Brewers' RiceThe small milled fragments of rice kernels that have been separated from the larger kernels of milled rice. Brewers' rice is a processed rice product that is missing many of the nutrients contained in whole ground rice and brown rice thus reducing the quality.
CassavaA starchy root of a shrub, high in carbohydrates. A good source of Manganese and Vitamin C.
CelluloseA source of dietary fibre, which comes from the cell wall of plants. It is indigestible, so higher levels are added to foods intended for hairball control and low-calorie foods as cellulose bulks out the food, while providing no calories.
DigestAnimal tissue that has been treated with heat, enzymes, or acids to produce a concentrated product intended as a natural flavouring.
EggA great source of high-quality and easily digestible protein, as well as fats and various minerals and nutrients.
Flaxseed (Linseed)Contains high levels of dietary fibre, as well as Omega 3 and Omega 6 fatty acids, which are required for good skin and coat health. Also contains lignans (natural antioxidants), and micronutrients.
Hydrolysed Animal ProteinProtein that has been broken down into its component amino acids - usually by boiling in a strong acid, or an enzyme. These proteins are so small, they are not recognised by the animal's immune system so can't trigger an allergy. This means they are good for allergy-prone pets.
Maize (Corn)A source of protein - used as an alternative to grains like barley, oats or rice. Is considered by some to be more likely to cause food intolerance.
Maize GlutenA by-product of Maize processing, which is used as a cheap protein source. Harder to digest than meat protein, and can cause health issues.
MealMeat Meal is produced by grinding up and cooking animal leftovers, which is then dried. The drying process creates a more concentrated product, with higher protein levels than fresh meat. Generally speaking, specific animal meals will be higher quality than generic (e.g., "Chicken" is better than simply "Meat" or "Poultry" Meal).
RiceContains lots of natural nutrients, and is a good source of fibre. Brown rice is more nutritious than white rice, and is easily digested.
Soya/SoybeanA low-cost source of protein, however it is harder to digest than meat proteins, and has been linked to food intolerance and allergies.
TapiocaA starch extracted from the root of the Cassava plant, which is high in carbohydrates but otherwise not particularly nutritious.