Internet myth that aspartame is deadly to dogs is wrong

05/21/2014 4:27 PM

05/21/2014 4:29 PM

Q: I just read something on the Internet that said aspartame causes pets to go blind and get brain damaged. I’m careful about not giving them anything with artificial sweeteners in them since I know some of them can kill pets, but I had no idea that aspartame was one of them. Is this true or is it only another Internet horror story?

A: Well … no. Aspartame, while probably not particularly good for anyone, has no unwanted side effects that we know of. Not at the doses we’re offered in consumer products, anyway. But I do know how the rumor got there.

A few years ago I received one of those mass emails written by a bereaved dog owner who claimed her dog went blind and died suddenly after eating sugar-free yogurt that contained aspartame.

Methanol poisoning, she claimed, was what the vet said had killed her dog. But never fear: Aspartame will not lead to sudden death! Not in dogs or cats.

Nonetheless, it is true that aspartame will be metabolized into methanol by the body. And because methanol toxicity can lead to blindness and brain damage, the rumor was born.

Thing is, the body can safely metabolize small amounts of methanol. And as it turns out, no animal could possibly consume enough aspartame to overwhelm this process. Consequently, aspartame poisoning is simply impossible.

What more than likely happened to occasion this dog’s death, if indeed this was a true story (Beware: many Internet tales are not), is that the dog consumed a yogurt containing xylitol, a sweetening substance increasingly found in all sorts of “sugar-free” consumer products –– including toothpaste, mouthwash, gums, mints, candy, desserts and yogurts, too.

Because xylitol leads to a rapid drop in blood sugar, many dogs will collapse and suffer seizures. If they’re not rushed immediately to the hospital they often die. In some cases, sudden death will ensue even before any other signs. If they survive, they may still suffer liver failure.

Unfortunately, many pet owners are still unaware of this “natural” sweetener’s extremely toxic effects. In fact, it’s way more toxic to dogs than chocolate. And yet most dog owners are still in the dark about the poisons that lurk in their pockets and purses.

Thanks for giving me an opportunity to dispel yet another game of Internet telephone: No, aspartame does not kill. And for the chance to let everyone know that xylitol does.

Dr. Patty Khuly has a veterinary practice at Sunset Animal Clinic in South Miami. Her website is Send questions to

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