Clinical veterinary nutritionist Dr Marge Chandler says we should look for a couple of key words on the label. “Dog and cat owners need to make sure that someplace on it, the package says it’s a complete diet – or it might say ‘complete and balanced’,” she says.

To be described as complete or balanced means that a dog or cat food fulfils The European Pet Food Industry requirements for nutrients, of which there are around 37 for dogs and 40 for cats. These are important because eating foods devoid of these nutrients may mean an animal’s diet is imbalanced or deficient, which can lead to health problems ranging from a poor coat to bad stools – or as Marge warns: “If it’s severe enough, say in a cat, the wrong diet can cause blindness and heart disease, problems with immunity, problems in energy levels.”

Though these are extreme health conclusions, Marge points out that animals that miss out on key nutrients may not show any signs of a problem for a long time. So owners should read pet food labels carefully rather than presume that all is well if their animal is gobbling its food happily and seemingly well.

What else do owners need to know?

Marge says that it’s a good idea to pick a food that matches your pet’s life stage.

“The label might say ‘complete food for an adult animal’ or perhaps ‘complete food for a puppy or kitten’. But,” she emphasises, “if it says ‘complete for all life stages’, which always sounds very good, that basically means that it’s a puppy or kitten diet and may not be completely appropriate for a senior pet.”

There is a lot to ignore on pet food labels too, Marge notes. Words such as ‘gourmet’ and ‘hypoallergenic’ mean very little, she says, and are often used simply to sell food as there is no legal definition for these terms. In other words, they are meaningless.

“Technically there is no hypoallergenic diet,” says Marge, “if your pet is allergic to any of the ingredients then it’s not hypoallergenic for them!”

Don’t fall for the marketing gimmicks, says Marge. “For example, the idea that something like grain-free is better – there’s no evidence at all that dogs and cats need a grain-free diet. There are very few gluten-intolerant dogs or cats. Of course there are exceptions (such as some Border Terriers or Irish Setters), but the vast majority of dogs and cats are not.”

Marge is keen to dispel the myth that meat by-products or derivatives are a bad ingredient in pet food. “The idea that these are low-quality ingredients is actually incorrect,” she says. “It’s actually a very environmentally friendly way of using what is actually very good ingredients that humans choose not to eat.”

Wet and dry foods can both have their place in an animal’s diet – and there are times when a wet food can be beneficial. “As cats get older, if they have things like kidney disease or diabetes, we need to get water into them and one of the ways you can do that is to feed a wet food.” She advises feeding young cats both dry and tinned food when they’re still forming their ideas of what to eat. “My reasoning for that is that at some point in their lives it might be that you need to feed them a therapeutic diet – and it may come as canned or just as dry.”

For oral health, there are some specific dry kibbles that have an abrasive, toothbrush action on the tooth and are designed to improve oral health and to remove plaque to prevent gum disease. However, Marge says most standard dry pet food won’t do so. “Toothbrushes are best for this,” she says.

When it comes to feeding pet rabbits, the Rabbit Welfare Association & Fund advises that owners should feed a diet that mimics what rabbits would eat in the wild. This should be around 80 per cent hay or grass, 15 per cent leafy greens and just five per cent pellets. Fresh, dust-free hay or grass helps wear down rabbits’ constantly growing teeth to prevent dental problems. Though a good source of vitamins and minerals, if rabbits rely too heavily on commercial food, they can tend to eat quickly and then become bored (and possibly destructive!).

Other small animals or rodents need careful attention too. For example hamsters need high levels of protein while guinea pigs must have vitamin C. It’s best to check RSPCA recommendations for individual species and, as with cats and dogs, read pet food labels carefully to ensure that any commercial food you buy provides a balanced diet.