No matter what pet you have, you will need to offer them a diet that provides all the nutrients they need in order to thrive. From our standard furry friends such as cats and dogs, to more exotic pets such as tortoises and parrots, there are different types of food that can be offered to them. 

You may notice that some foods are marketed as complete food, whereas others are called complementary foods. Let’s explore the differences between the two and the reasoning behind their formulations. 

What is a complete food? 

A complete food is exactly what it says on the tin. It provides a complete diet for the animal that is eating it, giving them all the nutrients they need in order to function correctly. Keep in mind that there are different qualities of complete food, and it is important to use a reputable brand – ideally, a company that does batch-level diet testing to ensure there are the correct nutrients in the food as fed, not just an appropriate list of ingredients – to offer your pet the best possible quality. 

A complete food must contain sufficient vitamins, minerals, and nutrients to keep your pet fighting fit. It should also meet the energy requirements of your pet, regardless of their activity levels. For example, a complete food for cats should contain taurine, an essential amino acid that cats must obtain from their diet. 

Nutrients are the building blocks of any diet and each plays an important role in different body functions. This requirement can change depending on the animal’s health, life stage, pregnancy status, or working lifestyle. 

Complete food for cats and dogs? 

A complete diet can vary significantly depending on the animal. For example, a complete diet for a rabbit will be entirely different from a complete diet for a cat. 

A standard complete diet for cats and dogs includes: 

High-quality protein  

Proteins such as chicken, lamb, and turkey are brilliant for helping carnivorous animals with a variety of body functions. Proteins help repair and develop muscles, support the immune system, and provide the body with plenty of energy.   

Proteins also contribute to maintaining healthy skin and hair, support milk production in pregnant and lactating animals, and help maintain a pet’s body condition.   

It’s safe to say that proteins are very important, and are usually needed in larger quantities, and higher quality, for carnivorous animals. 

Fats  

Fats play a crucial role in providing energy to the body, especially in active or working dogs. Fats also support skin and coat health, promote cell function, and enable the body to absorb fat-soluble vitamins, such as vitamins A, D, E, and K.   

One of the most common fats found in pet food is chicken fat, but sunflower oil is sometimes used, along with beef and pork fat. 

Carbohydrates  

While more common in dog food, carbohydrates can also be found in cat foods in smaller amounts. Cats are obligate carnivores, meaning they need more protein and don’t need much carbohydrate (although they can use them).   

Carbohydrates provide energy, fibre, and nutrients. Common carbohydrates in pet food include rice, oats, wheat, and corn. Vegetables like potatoes, peas, and pumpkin are also used as sources of carbohydrates. 

Vitamins and Minerals  

These are essential for the health and well-being of cats and dogs and support a variety of bodily functions. Key vitamins that should be included in a complete food include:   

  • Vitamin A – Supports skin health, the immune system, and vision.   
  • Vitamin D – Promotes healthy bones and teeth while helping the body absorb calcium and phosphorus.   
  • Vitamin C – Acts as a natural antioxidant, helping to protect the cells in our pets’ bodies from damage. Although cats and dogs can produce their own Vitamin C, some diets still include it to extend the product’s shelf life naturally. 

A variety of other vitamins are necessary to keep your pet happy and healthy. Minerals also play an important role, including calcium, phosphorus, and magnesium. 

What is a complementary food? 

Complementary food can be described as nutritionally incomplete and cannot be fed as a sole diet. Complementary foods must be offered alongside a varied, complete diet. 

While complete foods provide pets with all the nutrients they need, complementary diets lack essential vitamins, minerals, proteins, and fats, and are manufactured to be given alongside a pet’s regular food. 

Examples of complementary foods include: 

Pet treats:  

These should only be offered as treats and are not formulated to be given as a sole diet. They are usually high in calories and fat content to make them more palatable. 

Food toppers:  

Sachets filled with food toppers usually consist of meat, gravy, and vegetables. These are made to make food more appetising, but they often contain higher levels of sodium and fats. 

Some wet foods:  

Dry kibble is often combined with wet food. Either the bag of kibble or wet food packaging usually details what foods to mix. 

Raw/cooked meats:  

A diet consisting of only raw or cooked meats can be considered a complementary diet. This is because purely offering meat is unlikely to provide the necessary vitamins and minerals, unless offal, a source of fibre, and bone components are included. 

Raw food can be a controversial topic, so you should carry out plenty of research if you are considering feeding a raw diet. 

You may wonder, what’s the point of complementary food? These foods are often given as a treat to offer some variety or to make a main meal more palatable. Complementary foods are also a brilliant way to train pets, as the reward is often tastier than their usual diet! 

Complete food for cats 

We’ve established that complete pet foods are best for a full-time diet, so let’s look at some of the options suitable for our feline friends: 

Hills Cat Food – This reputable company works globally and collaborates with veterinary practices to offer a range of diets, as well as performing significant amounts of nutritional testing, rather than relying on “recipe book” formulation. These include both everyday complete diets and prescription foods for certain conditions, such as kidney disease, obesity, and diabetes.   

Hills products are available in many forms, such as Vet Essentials, which can be purchased online or from your veterinary practice, and Hills Science Plan, which is available in most pet stores. 

Lily’s Kitchen – Offering both dry and wet forms of cat food, Lily’s Kitchen is a popular brand found in supermarkets and pet stores. They provide foods to suit different life stages and use fresh meats and vegetables. 

Royal Canin Cat Food – Similar to Hills, Royal Canin is available worldwide and works with veterinary practices to promote high-quality pet food; likewise, they have a very active research unit and perform their own nutritional testing. They offer formulations based on life stage and specific diseases, ensuring your pet’s needs are met. 

Complete food for dogs 

Like cats, dogs require a complete diet throughout their lives, in either wet, dry, or mixed forms. Popular choices include: 

Hills Dog Food – Similar to their cat food range, Hills offers Vet Essentials and Science Plan for dogs, with options for different life stages and medical conditions. Hills dog food includes a variety of ingredients and typically over 50 nutrients, making it a comprehensive choice. 

Tails – This brand creates tailor-made food for your dog based on their individual needs. Whether you have a working dog or an older one, Tails adapts the recipe as they age and offers a variety of flavours. They also include beneficial extras such as salmon oil and glucosamine to promote healthy joints, skin, and hair. 

James Wellbeloved – A well-known brand stocked in veterinary practices and pet stores, James Wellbeloved uses top-quality ingredients with added vitamins and minerals. They boast that they avoid preservatives, colourings, and synthetic flavourings, ensuring a natural diet for your dog. 

Complete food for exotic pets 

Exotic pets can also be fed a complete diet, depending on the species. For example, many reptiles can live solely on a diet of insects such as locusts, mealworms, and crickets. Lizards, such as Crested Geckos, require a mixed diet, but many liquid foods and fruit purees can be considered complementary, as insects typically suffice. 

Ferrets are another example of an exotic pet that can be given a complete diet. This should be high in animal proteins and fats and low in carbohydrates. Raw meat and eggs can also be offered as part of their diet. 

If you’re unsure about the right complete diet for your exotic pets, speak with a veterinary surgeon or your local exotic pet store for guidance. 

Final thoughts on complete vs complementary food 

The main difference between complete and complementary food is the nutritional composition. Complete foods provide pets with all the nutrients they need to function correctly, while complementary foods are designed to be fed alongside a complete diet. 

If you’re unsure about what food to offer your pet, always consult your veterinary surgeon. They can advise you on the best food for your pet’s specific needs.