What can dogs and cats taste?
We've all seen the ads where pets experience visible joy when served an expensive brand of dog or cat food. But do dogs and cats discern flavors, and given the choice, would they prefer Alpo or Cesar to dog crap or dead rats?
Even the most doting pet parents can have a tough time maintaining the illusion they’re dealing with a refined sensibility. The high-end kibble might indeed disappear from your dog’s dish, but that doesn't mean she can’t find room for a bird corpse or discarded diaper afterwards. Yes, dogs and cats do apparently taste flavors, but no, the fancy brands don't necessarily contain more of what gets them salivating than the cheap stuff, just as beluga caviar won't necessarily trip human taste receptors more reliably than a bag of Doritos.
Taste starts with the tongue, and the number of taste buds varies drastically among species — in some cases, pretty widely within species too. Chickens have only about two dozen taste buds; humans tend to have somewhere between 2,000 and 10,000. A bigger number doesn’t automatically translate to a more sophisticated palate: catfish have hundreds of thousands of external buds, meaning they’re constantly tasting the river-bottom muck as they swim through it. I'll take the life of a chicken, thanks.
As for dogs, they have just 1,700 taste buds; cats make do with a paltry 470. In both, you won’t be surprised to learn, many of these buds are particularly attuned to meats, fats, and the chemicals therein. Beyond basic meatcentricity, though, we see some divergence. Sweet tastes, for instance, also make it onto dogs’ radar — their taste buds respond to a chemical called furaneol, found in various fruits. (Note that they go for chocolate, even though it's toxic to them.) Cats, on the other hand, are alone among the mammals in having no ability to detect sweetness — which, given the personality of some cats I've known, seems poetically fitting.
And it makes sense: foodwise, one of the big differences between the two major pet blocs is that cats are wired to eat a lot more protein than dogs. In recent studies of macronutrient selection — where test animals had access to a buffet of variously high-protein, high-fat, and high-carbohydrate foods and ate what they wanted — British pet nutritionists report that cats chose a nutrient balance of 52 percent protein, 36 percent fat, and 12 percent carbohydrates, whereas dogs’ self-selected splits came out at 30 protein, 63 fat, 7 carbs.
Why the gap? The researchers suggest that until not too long ago, humans weren’t setting aside much meat for cats, who were expected to make their nutritional numbers via mousing — and the small animals cats remain famous for hunting tend, in fact, to contain about 50 percent protein. Dogs, conversely, are descended from pack hunters, who could land bigger prey with more body fat; then, of course, they tossed in their lot with people at least 15,000 years ago and have been eating our scraps ever since. (From a scavenging perspective, a dog's occasional willingness to eat actual turds isn’t as nutty as it seems — who knows, it figures, maybe there’s still some good stuff in there.)
Now, taste and smell are overlapping senses for most animals, and you and I aren't even in our pets’ league when it comes to detecting scent. Humans have maybe six million olfactory receptors in our noses, where cats can have up to 80 million and dogs as many as 300 million. Dogs and cats are also among the many critters whose mouths connect to their nasal passages through something called the vomeronasal organ, or Jacobson’s organ, containing its own set of receptors to detect chemicals like pheromones. Scientists are still studying this organ's role, but with what’s essentially a second olfactory system running alongside the first one, pets may encounter their food via a multisensory experience it'd be hard for us to even comprehend.
With that said, there's no solid evidence that dogs and cats are biologically predisposed to favor the flavor of a higher grade of meat, whether marketed as “organic” or “natural,” to the organs and byproducts processed into cheaper fare. In fact, some bargain-brand dog foods may please your pet more, because they're highly sweetened. None of this means there aren't nutritional benefits to the pricier stuff, but I have neither the time nor the space to moderate the countless disputes over proper pet diet that have been stirred up in the two millennia since the Roman scholar Marcus Terentius Varro advocated feeding sheepdogs milk-soaked bread and marrowbones.
Then again, no dog ever lifted its muzzle from the trash to consider a more upscale dining alternative offered on television. Advertisers set their snares for the species that’s holding the credit card, and American humans are their willing prey, shelling out more than $20 billion on pet food annually. And it’s not like marketing types don’t know their psychology: according to a 2014 Cornell study, people will tend to believe that their own food tastes better the more they pay for it. Sometimes you have to wonder just how much smarter than our pets we actually are.