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How to choose the best dog and cat food

By Siobhan Chan

Not sure how to pick the best pet food for your dog or cat? We explain what goes into dog and cat food, and share advice from top vets.

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Choosing the right pet food can make all the difference to the health and happiness of your dog or cat. 

Signs that your pet is getting good nutrition include clear and bright eyes, a shiny and dandruff-free coat, plenty of enthusiasm for life, and a lack of excess body fat – you should be able to feel their ribs and see their waist. 

To help you find the right food for your cat or dog, we've asked pet food experts for their advice on how to choose dog and cat food - read on to find out what you need to know.

And see our reviews of pet insurance to make sure you're getting a good deal on pet care.

We've assessed some dog and cat foods from well-known brands to help you find a product that your pet will love, that's also easy on your wallet. 

Go straight to our pages on choosing cat food and choosing dog food to see the results of our pet food assessments

Complete vs complementary pet foods

Some pet foods are marketed as ‘complete’, meaning they contain all the nutrients an animal needs, while others are complementary, meaning they should be given to your pet alongside a complete food. 

All complete foods have to meet certain feeding requirements, so your pet should be getting all the nutrition that it needs, regardless of how much the product costs. 

Complete foods don’t necessarily cost more, but there may be an element of false economy with cheap foods, as each individual kibble can contain fewer nutrients. Always check the pack to see how much you should be feeding your dog or cat for their weight. 

With some dog foods, it will cost as little as £140 a year to make sure your dog has a balanced diet, but others can set you back by more than £850. The price difference is even more marked for cat food, with the cheapest brands we assessed costing less than £60 a year - and the most expensive wet foods being more than 10 times this amount. 

We've calculated the cost of feeding an average-sized cat and a small Labrador with the top brands in the pet food aisle in our guides to choosing the best cat food and the best dog food, according to the feeding guidelines on the packaging.

Only logged-in Which? members can see our dog and cat food advice. Log in or if you're not already a Which? member, get instant access with a £1 trial to Which?

What's in pet food - and how do I know that it is safe?

All meat in UK pet foods must, by regulation, be of a quality fit for human consumption and be made only from species that are already eaten in the UK. Food made by manufacturers that are members of the Pet Food Manufacturers’ Association must also meet regulatory requirements. 

Pet food that says it is ‘with chicken’ must contain at least 4% chicken, but a ‘chicken-flavoured’ product doesn’t have to contain any at all. High-quality pet foods tend to contain more meat – you can check this by looking at the ingredients list. 

The higher up the list meat is, the more it contains. But while proteins from meat can be better used in the body once it’s been digested, a mixture of plant and meat protein is important in a diet. 

The World Small Animal Veterinary Association recommends that you choose a pet food from a company that can provide a contact number for enquiries about its products. This way, you can call to check that the food has been developed with a nutritionist and tested using feeding trials to make sure that pets can digest it properly.

Vets answer your pet food questions

We asked some top vets and pet food experts about key issues when it comes to feeding your cats and dogs. 

Read on for advice from Professor Daniel Chan, professor of clinical nutrition at the Royal Veterinary College; Gudrun Ravetz, junior vice president of the British Veterinary Association; and Vicki Larkham-Jones, a vet with veterinary charity PDSA.

I think my pet is becoming overweight – what can I do? 

‘Always check the packaging to see how much your pet should be eating for the weight they should be, not the weight they currently are,’ says Vicki Larkham-Jones. Weigh out the exact amount of food needed so you aren’t swayed by puppy-dog eyes as you prepare dinner, Vicki adds. And if you’re giving your pet a treat, give them a bit less food to balance out their diet for the day. 

Is preparing homemade pet food a good idea? 

‘It’s extremely difficult to put together a balanced homemade diet for your pet, and I wouldn’t recommend it unless you’re under the direct supervision of a vet,’ says Gudrun Ravetz. Professor Chan also warns that feeding a raw diet could lead to bacteria spreading around the home, which could have an impact on your health. 

Do pets need different food as they get older? 

‘Yes. It is essential that puppies and kittens are fed on puppy and kitten food, as they have specific energy and nutrient requirements,’ says Gudrun. ‘As they get older, different breeds of dog will age at different rates,’ she says. ‘For example, a Great Dane is likely to be “senior” before a Yorkshire terrier.’ ‘Your vet will be able to advise on the best type of food for your pet’s life stage, breed and lifestyle, and tell you if your pet has any special dietary needs.’

Can I give my pet a vegetarian diet? 

Cats are carnivores, and a vegetarian diet is not recommended for them. This is the same with dogs, although, in theory, it’s easier to find and feed your dog a vegetarian diet that will still meet its needs,’ Gudrun says. However, she warns that it can be difficult to do it well and, unless you work with a veterinary-trained nutritionist, there is a risk of harm to your pet’s health.

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