Is it a terrible idea to make your pet a vegan?

Should cats and dogs really be eating a plant based diet? Photo / Getty Images

If all the dogs and cats in the US alone got together and became a sovereign nation, it would rank as the fifth largest in terms of meat consumption.

That's according to a first-of-its-kind study last year by UCLA professor Gregory Okin which looked at the environmental impacts of food consumption by dogs and cats. Meat consumption takes a serious toll on the environment — and our furry companions aren't without blame.

Some people insist on treating their pet animals like children (not pointing any fingers) and sometimes that can manifest itself in unusual ways. For a variety of reasons, one small but growing trend in pet ownership has seen owners trying to kick their animal's meat habit.

But can you help save the planet by giving your pets a non meat diet or is it a recipe for disaster?

Emeritus Professor David Fraser from the Faculty of Veterinary Science at Sydney University is sceptical about the trend of vegetarian pets.

"I think it is a very dubious habit that people have if they want to convert their carnivorous dogs and cats into vegetarians, however it is possible to do it but it really is very difficult for people who have no particular nutritional knowledge," he told news.com.au.

"There's several problems associated with it. One is of course palatability. The natural diet of dogs and cats, particularly cats, is entirely a carnivorous one and the things they find palatable are usually only found in animal tissue," he said.

"The other thing that is a particular problem is that both dogs and cats — again particularly cats — have evolved to require very specific nutrients which can really only be obtained from a carnivorous diet.

"You can buy those nutrients as purified substances and add them to a vegetarian diet and that would solve the problem," but you would need to be very careful and know what you're doing, he said.

Cats and dogs have very different needs. Dogs are a fair bit more adaptable when it comes to their food and there has even been reported cases where it has proved beneficial when vegetarian dog owners "aligned their pets' lifestyles with their own."

While both animals can benefit from vegetarian inclusions in their diet, "a majority of their diet should be based on meat and meat products," Prof Fraser said.

If not, one common problem that could arise is calcium deficiency. "In the wild they would be getting the calcium from eating the bones they would find in the prey they killed," he said.

Also your cat is possibly more likely to go hunting and kill local native fauna if you deprive it of meat.

Despite warnings about potential health problems, the trend of non-meat diets for dogs and even cats has been growing in recent years and there are plenty of dietary products on the market in Australia to accommodate the movement.

"I am aware that there are some commercial vegetarian diets for dogs and cats that would be formulated for their special needs," Prof Fraser said. "If the animal can actually eat that type of diet then it's quite possible that they will be able to maintain good health from a nutritional point of view."

For instance, Sandy Anderson is the owner of Australia's first vegan pet-food company, Veganpet, and teamed up with Nick Costa of Murdoch University's School of Veterinary and Biomedical Science to develop a "complete and nutritionally balanced" vegan pet-food range using human-grade organic products.

Meanwhile the Cruelty Free Shop which has stores in Sydney, Melbourne, Brisbane and Canberra also sells vegan pet food for both dogs and cats. If you go online, there are plenty more options to give you pet a meat free lifestyle.

While products and stores like this have been catering to the unusual trend in the past decade, as Prof Fraser points out, the real problem is when people attempt to switch their pets onto a non-meat diet on their own accord and without the requisite knowledge.

In 2013 a kitten nearly died as the result of a vegan diet after its owner reportedly fed it a diet of potatoes, rice milk and pasta.

The animal was taken to Melbourne's Lort Smith Animal Hospital and was very weak, prompting a warning from the clinic about the dangers of people "forcing ideologies" on their pets.

"What I think is a more interesting question," Prof Fraser said. "Is what is the motivation of these people, when they know these are carnivorous animals? Are they trying to harm them because a lot of times that's what can end up happening," he said.