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We often hear that veggies are good for us. For the sake of our health and the planet’s health we should be consuming and producing much less meat.

Yet not everyone in your neighbourhood can boast he’s “strong to the finish ‘cause I eats me spinach.” Cats can go blind and die if forced onto a vegetarian diet.

Taurine Deficiency Causes Blindness

“Cats cannot make do on a vegetarian diet because it provides no taurine,” says Øystein Ahlstrøm.

He is an associate professor at the Norwegian University of Live Sciences (UMB).

Taurine is an amino acid, more precisely it is known as 2-aminoethanesulfonic acid, and it’s vital for eyesight.

“The nerve cells that register an image in the eye are rich in taurine. If a cat doesn’t get enough taurine its retinas deteriorate.

“The cat’s eyesight will be reduced. You would notice this because it would have trouble calculating distances or start bumping into things,” says Ahlstrøm.

It does not take long for these problems to develop.

Enlarged Heart

“After six weeks without taurine the symptoms become noticeable, but total irreversible blindness occurs only after a long-term deficiency.

When the taurine takes its leave the retinas degenerate and eventually the cat will go blind. But sight is not the only thing it can lose – its life is also at risk.

“Cats with a taurine deficiency can suffer reproductive disturbances and their heart muscles can become weakened and enlarged. That can kill them,” he explains.

This is not just a complication for cats. Other animals, and people too, need their taurine.

The diets of cats over the past few million years have led to the difference between their tolerance of a vegetarian lifestyle and ours.

A Mouse a Day Keeps the Doctor Away

“As cats have been eating meat for several million years, they’ve lost the ability to produce taurine,” says Ahlstrøm.

Cats have specialised as carnivores, whereas dogs, for instance, eat just about anything.

Meat and fish contains a lot of taurine, but you could poke through your veggies forever without finding any.

Felines have always satisfied their taurine requirements by eating other animals.

As they haven’t needed to expend any energy on synthesising their own taurine, evolution has removed this capability.

Animals that are a little more omnivorous than cats still have this ability.

“Dogs can produce sufficient amounts of taurine from amino acids. Cats can’t, so they have to get taurine in their diet,” he says.

This does not give you the green light for turning your dog into a vegan − if you were tempted.

Forget About It

“If you want to give a vegetarian diet to a pet, get a rabbit, not a dog or a cat,” says Bjarne Braastad.

Braastad is a professor of ethology − the study of animal behaviour − at UMB.

He says people in Norway are prohibited from putting their dogs or cats on vegetarian diets, because it is contrary to their nature. It would put their health and well-being at risk, and thus it is a breach of the country’s Animal Welfare Act.

Both scientists at UMB add, however, that you wouldn’t have much luck getting your cat to eat like a rabbit.

Cats Are Fussy

“In general a cat can’t be harmed by food, because if the food is harmful it won’t eat it,” says Braastad.

“Dogs eat things that are bad for them, whereas cats are smarter at figuring out what’s favourable and what isn’t”

Ahlstrøm adds: “Cats are finicky, and they generally dislike vegetarian food."

“Another matter is that felines lack the ability to taste sugar or sweetness, and they prefer sour foods.”

“Vegetables have no nutrition that cats need. It won’t hurt your cat to eat a salad for starters, but it can’t be the main course,” says Braastad.