Pets are being put at risk by owners who feed them a vegetarian diet, experts have warned.

Sales of meat-free pet foods are increasing by up to 25 per cent a year. But an unsuitable vegetarian diet for cats can lead to blindness, brain damage and even death.

In dogs it can cause heart problems, stunted muscle growth, skin problems and general lethargy.

Danger: Pets are being put at risk by owners who feed them a vegetarian diet, experts have warned (file picture)

Growing popularity: Sales of meat-free pet foods are increasing by up to 25 per cent a year

Gudrun Ravetz, junior vice-president of the British Veterinary Association, 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.’

Owners may not realise the harm a meat-free diet can cause because cat and dogs are stoic animals, but Mrs Ravetz said pets can suffer irreversible health problems within months.

Daniel Chan, professor of emergency and critical care medicine and clinical nutrition at the Royal Veterinary College, added: ‘There is a danger a pet owner may believe that what they are feeding their animal is sufficient when it is not.’

He said 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.

Mr Chan added that while it is possible to feed dogs and cats a meet free-diet, he said the industry was not regulated enough to ensure all the products were adequate.

Damian Eadie, who runsVegeco, a vegetarian pet food business, said he has received death threats over his vegan cat food.

But he said it meets European standards and includes taurine – an amino acid that prevents blindness and certain kinds of heart disease.