People who feed their cats a vegan diet are at risk of breaking animal welfare laws, according to the RSPCA.
A spokesperson for the charity told The Telegraph that feeding cats - who are often described as 'obligate carnivores' - a meat-free diet could result in a breach of the Animal Welfare Act.
The advice follows the appearance of the latest in non-meat and vegan pet foods at the National Pet Show in Birmingham (UK) recently, coupled with a steady rise in demand for such products from concerned consumers wanting specialist alternatives for animals under their care.
Animal Welfare Act
"Under the Animal Welfare Act, the law requires an owner to take reasonable steps to ensure that all the pet's needs are met," the spokesperson is reported to have said.
"This includes a healthy diet, as well as providing suitable living conditions, ability to behave normally, appropriate company and protection from pain, suffering, injury, and disease.
"Dogs are omnivores and can eat a wide variety of food types so they can survive on a vegetarian diet as long as the diet is well-balanced. Cats are strict carnivores and depend on some very specific nutrients that are found in meat including taurine, vitamin A and arachidonic acid so can become seriously ill if they are fed a vegetarian or vegan diet.
"If an owner is considering switching their pet's diet they should consult with their vet to make sure that it will meet all their pets nutritional needs which will depend on many factors such as age, health and lifestyle."
The UK's Vegetarian Society agrees that cats in the wild are obligate carnivores, but points out that there are 'commercial vegetarian foods available that contain synthetic versions of essential nutrients' for domestic cats.
"It is the owner's responsibility to feed their pet a balanced diet suitable for its age, lifestyle and health status. We would recommend seeking advice from a vet before changing your cat's diet."
Dr. Andrew Knight – Professor of Animal Welfare and Ethics at the University of Winchester – is such a vet, and sees problems with feeding companion animals so-called traditional, meat- and fish-based pet foods.
"As a companion animal veterinarian with a particular interest in the health and nutritional issues surrounding vegan companion animal diets, I've trawled through the scientific literature for studies describing their adverse effects," he said in a blog post for The Vegan Society.
"Oddly perhaps, given the strength of 'urban wisdom' on this issue, I've struggled to locate any scientific evidence demonstrating that cats and dogs fed well-planned and nutritional vegan diets are less healthy than the norm.
"Yet, I have found evidence of one kind. I've accidentally located more than 10 published studies documenting hazardous ingredients in commercial meat-based diets, or adverse health effects in cats and dogs maintained on them. Interested readers will find them summarized here."
Complete and balanced
Knight says that ensuring that the diets of kitty friends are nutritionally complete and balanced is key to ensuring health and vitality. Several companies exist that claim to provide such non-meat pet foods, including products specifically developed to meet the needs of cats.
Italian brand Ami has been formulating meat-free pet foods for more than a decade and distributes its products to over 25 countries across the globe. Its hypoallergenic complete cat food has been designed to 'solve typical problems of poor nutrition: heavy or slow digestion, appetite and fatigue'.
The UK's Benevo launched its vegetable-based dry cat food in 2005, followed by a moist food for dogs and cats called Duo in 2006. Both flavors are free from genetically-modified ingredients and include vegan-sourced taurine, among other essential vitamins and minerals.
*This story was updated on November 26. It initially said the RSPCA had warned that those who fed cats a vegan diet could be at a risk of a jail sentence. The RSPCA says it made no warning, and added that it would not prosecute people for feeding their companion animals a vegan diet.