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Why Cats Can't Taste Sweetness
Dysfunctional Gene Discovered In 2005
How many times have you heard someone say, "Well animals are attracted to antifreeze because there's a sweetness to it that they like." Nice try, Bucko, but it strikes a sour note with cats, because cats can't taste sweetness. All they can taste is salty, sour and bitter.
Isn't that a crummy way to go through life? It would be for us humans, with our gazillion taste buds. But for cats, which have fewer than 500 taste buds, no problem. Dogs don't fare much better, with about 1/6 the taste buds we have. With both species' aroma is the palatability trigger.
If it passes their sniff test, it usually goes down. Texture is also an important palatability factor, and that covers a variety of complex considerations for the cat or dog, depending upon whether he's evaluating dry kibble or canned food.
For cats, kibble comes in various sizes, shapes and textures. Shapes include balls, discs, cubes (with rounded corners) "X's," and "O's," for example. While an animal may approve of the size, he may not approve of the shape of the kibble. Then there's one more hurdle: what the surface feels like.
Some kibble is smooth, some is coarse, some is hard and breaks into a couple of pieces, some is softer and crumbles in the mouth. If I were a betting man, I'd bet that the vast majority of dogs wouldn't give a second thought to all of that. Hell, they'll eat TV remotes, coins and road kill.
Cats on the other hand, bless their little hearts, do give a second thought to all of that. And just to exasperate you more, they'll give a third and fourth thought to it. Are there any cat owners among you who have a collection of different foods in the closet? Look at all those hands go up!
Canned food is usually less of a problem. It comes, basically, in two types. There's the loaf or pâté stuff with the consistency of that canned, ground-up luncheon meat and God knows what else, and there's the stuff that's like a stew. Both dog and cat foods come in those forms. Dogs usually don't care, cats sometimes do.
But the reason cats can't taste sweetness has nothing to do with aroma or texture. The receptor that recognizes sweetness involves two genes, and in cats one of these genes is dysfunctional. Those of us with a hyperactive sweet tooth would really appreciate such a dysfunctional gene.
It has long been believed that cats had a weak sense of taste, but that it was better developed than a dog's. I learned over the years, from several sources, that cats favored foods that were acidic. But researchers at the Monell Chemical Senses Center isolated the dysfunctional gene.
The facility is a non-profit research institute in Philadelphia and news of the discovery was released in 2005. They had discovered the defective gene in the big cats back in the 70's. The existence of the defective gene has spawned some "chicken or the egg" debate.
Are cats obligate carnivores because they have the defective gene, or did the gene become dysfunctional because they were obligate carnivores and didn't utilize it? An interesting dilemma for sure, but I have my own dilemma that's keeping me awake at night.
What does cantaloupe taste like to my cat, Fluffy? In her youth I caught her up on the counter finishing off what I left attached to the rind. In her later years if I cut open a fresh cantaloupe, no matter where she was in the house, she'd be at my feet in seconds.
Cantaloupe tastes sweet to me (thank you functioning sweet-gene), but she can't taste the sweetness. And another thing, why doesn't she react similarly when I crack open a honeydew melon?
It would be nice if the Monell folks answered that one. Anyway, your cat doesn’t drink anti-freeze because it’s sweet. It must smell appealing to her.
By the way, if your cat walks through a puddle of antifreeze that contains ethylene glycol, and licks her paw, she’ll likely ingest enough to kill her. About five tablespoons of it will kill a medium size dog. It destroys their kidneys. Be sure to wipe up spills in the driveway or garage.
The "pet safe" antifreezes on the market use chemicals such as propylene glycol, which has a low freezing point and a high toxicity level. It can be safely consumed below its toxic level. In fact, it's used as a moistening agent in some human and pet foods and treats.
© 2012 Bob Bamberg