For many vegetarian pet owners, it seems only right that their beloved cat or dog should follow their example.
But the trend for meat-free pet food is putting animals at risk of serious health problems, warn experts.
An unsuitable vegetarian diet for cats can lead to blindness, brain damage and even death, while in dogs it can cause heart problems, stunted muscle growth, skin problems and general lethargy.
Sales of meat-free pet foods are increasing by up to 25 per cent a year, with vets saying most people fed their pets a vegetarian diet because they believe meat-eating is wrong - not because they consider it a healthier option for the animal.
Gudrun Ravetz, junior vice-president of the British Veterinary Association, said pets can suffer irreversible health problems within months of adopting a meat-free diet - and owners may not realise anything is wrong until it is too late.
Mr Ravetz told The Sunday Times: "In the case of dogs, if someone is determined to do it, it's theoretically possible but it is much easier to get it wrong than to get it right and owners would need to take expert advice.
"You can't realistically feed cats a vegetarian diet because it is so difficult to deliver what they need without meat that the risk is too high."
Professor Daniel Chan of the Royal Veterinary College added that the industry was not regulated enough to ensure all the products were adequate.
- Daily Mail