Why Do Cats Have Rough Tongues? (According to Science)
One of the most polarizing things about dogs is their eagerness to kiss you. If you get anywhere near their faces, there’s a good chance that you’re getting a tongue bath. Some people love it, others hate it, and dogs don’t care either way.
But what about cats? Not many people like a kiss from a cat, and there’s a good reason for that: their tongues feel like sandpaper.
It seems odd that dogs would have such smooth tongues while cat tongues are so rough; after all, both evolved to be predators, right? What’s the deal with cat tongues?
Let’s find out what the science says!
What Makes Cat Tongues So Rough?
The reason a cat’s tongue is rough is that it’s lined with backward-facing spines called papillae. These spines are made of keratin, just like our hair and nails, and they run up and down the length of the cat’s tongue, though they’re mainly clustered in the middle.
You can actually see the papillae on their tongue if you look close enough. Your cat isn’t likely to just sit there with their tongue out while you examine it, though, so you might want to try snapping a quick picture.
Don’t worry if this is news to you — scientists are still learning about all this. In fact, they’ve just recently discovered that papillae aren’t cone-shaped and solid, like they previously thought. Instead, they’re scoop-shaped and hollow.
This is important because it informs much of what cats use their rough tongues to do.
Image Credit: mik ulyannikov, Shutterstock
There’s Not Just One Reason
If you’re asking why cats have rough tongues, you’re looking at the problem the wrong way. There’s not a “reason” behind it: They’re the product of millennia of evolution.
As a result, there’s not going to be a single, pat answer to the question. The fact of the matter is that cats use their tongues for various purposes, and the roughness makes many of those jobs easier.
It’s impossible to say whether the rough tongues evolved because of their functionality or if cats just learned to make the best of the hand that nature dealt them. It’s probably not that important either way.
So, instead of looking for one single answer to the question, let’s look at all the ways that having a rough tongue benefits cats.
Cats can’t purse their lips and suck water the way that we can; instead, they stick their tongue in water and draw it back into their mouths quickly.
When they do this, the scoops on the papillae drag droplets of water off the surface, creating a spiral that the cat can then close their mouth around and swallow. It may not be quite as efficient as the way that we drink, but it definitely works for them.
Dogs, on the other hand, dip their entire tongue in the water and then curl it, scooping giant gulps of water into their mouths. It’s messy, as anyone who’s ever mopped up after a dog can tell you. Cats, meanwhile, only dip the very tip of their tongue in the water, and the papillae take care of the rest.
Their Tongue Helps With Grooming
Chances are that you’ve seen your cat spend most of their waking hours grooming themselves. While it may not seem like it, cats are actually efficient when it comes to hair care, and it’s all due to the papillae on their tongues.
The papillae help the cat’s saliva penetrate deep into their fur, all the way down to their skin. Remarkably enough, if you compress a cat’s fur, you’ll find that the distance to a cat’s skin through the fur is exactly the length of the papillae! (There’s one exception: the domestic Persian, which is why their fur is so prone to matting and tangling.)
Ensuring that saliva penetrates deeply enough to reach the cat’s skin has another benefit: it removes blood and other materials that could give your cat an unwanted scent. This is important for hunting purposes, and it also partially explains why cats’ tongues differ from the ones that dogs have.
With a few exceptions, cats are solitary hunters, so anything that could give away their presence could ruin their chance at supper, and that could eventually cause them to starve to death. Dogs, on the other hand, tend to hunt in packs, and they’ll run prey down over great distances.
It doesn’t much matter to a dog if you smell them coming — all that matters is whether you can outrun them. For a cat, though, it’s literally a question of life and death, so it’s a good thing that they have those rough tongues.
A Rough Tongue Helps Cats Eat
Assuming that a cat has been successful in hiding their scent and killing its prey, they now need to be able to eat enough of their quarry’s flesh to satisfy them, and the papillae on their tongue will help them do just that.
Papillae’s first purpose during mealtime is to help the cat get a firm grip on their prey. This is especially important when the cat first pounces, as the prey has a brief moment where they might have a chance to escape if they break the cat’s grip. Thanks to the papillae, few animals are successful in escaping.
Once their quarry is dead and mostly consumed, the rough tongues help them to remove every last bit of flesh from the animal’s bones. It works in much the same way that a cheese grater does, continually scraping off a bit more with every stroke.
Since a cat’s hunting success rate can vary wildly, they need to make the most of every meal, and their rough tongues ensure that they do.
What Happens When a Cat Loses Their Papillae?
You may have noticed that some cats — especially older ones — can have “bald spots” on their tongue that aren’t as rough as the rest of it. That’s because, like our human hair and nails, a cat’s papillae can break off — but unlike our hair and nails, they don’t grow back.
When this happens, it will be much more difficult for your cat to groom themselves, so you’ll have to pick up the slack. If you’ve noticed your cat starting to have smooth patches on their tongues, increase your grooming efforts accordingly, especially if you start noticing mats or tangles in their fur.
You should also take your cat to the vet, just to be safe. Oral herpes and other diseases can cause papillae to break off, so you should rule out something more serious going on.
The Weird, Wonderful, Rough Cat Tongue
While cat tongues may not be great for showing affection, they are fantastic for any number of other purposes. Given that much of the research on cat tongues is relatively recent, we’re likely still just scratching the surface of what these things can do (no pun intended).
Quincy never intended to be a cat person. He grew up around dogs, and when his wife brought home a kitten one day, he told her she had one week to find it a new home. That week turned into 10 years (his wife moves very slowly), and that kitten turned into three (they got two more, the kitten didn’t self-replicate). After a decade of sharing his home with three cats, one horrifying realization finally set in: oh God, he’s a cat person now, isn’t he???
