Why Are Cats' Tongues Rough?

Cat tongues are often described as being rough like sandpaper, but we can assure you that the structure of your favorite feline's tongue is far more fantastical than anything you'll find on the shelf of a hardware store. However, to see what's really going on would require a close inspection, and we doubt your cat would appreciate such an intrusion.

Lucky for us, some first-rate researchers have already done the hard work of not only showing the tongue's form, but also hypothesizing on the possible purposes behind its design.

Cat tongues look almost furry with the naked eye. But instead of hair, their tongues are covered in hundreds of tiny, backward-facing spines called papillae, says Laura Moon, DVM, of Green Hills Veterinary Clinic in Moberly, Mo. These sharp, scoop-shaped papillae are hollow and composed of rigid keratin, a hardened protein found in human hair and nails and in animal claws, horns, and hooves.

Interestingly, these papillae are something your cat has in common with his larger, wilder cousins. Micro-computed tomography (micro-CT) scans show similar structures across the tongues of domestic cats, bobcats, cougars, snow leopards, tigers, and lions.

Considering that your cat's tongue is covered in hundreds of mini spines, it's no wonder that it feels like sandpaper when dragged across your skin. And while we can only guess at the purpose behind this coarse composition, there are several research-based theories:

According to a 2018 study from Alexis Noel and Peter Hu, the papillae on a cat's tongue have two hollow regions that aid in grooming. The region at the tip is for wicking saliva from the mouth and depositing it deep into the cat's fur, and the flexible hollow base makes it easier to remove hairs that have gotten caught on the tongue. In other words, your cat's tongue is like a built-in, highly sophisticated comb.

Grooming serves many purposes, which is why cats spend nearly a quarter of their waking hours engaged in the task. Noel and Hu note that regular grooming is helpful in removing fleas, debris, and loose hairs, which can prevent the formation of painful mats and tangles that can lead to infection.

The ability of the papillae to deposit saliva deep into a cat's coat isn't just helpful for bathing—it's also an ingenious tool for thermoregulation, or helping cats maintain their body temperature. Because felines only have sweat glands in their paws, Noel and Hu say that grooming has long been suspected as a mechanism for cooling cats down. They found that papillae-facilitated saliva deposits close to a cat's skin can provide up to 25 percent of the cooling he needs for thermoregulation.

Cats are obligate carnivores, meaning they rely on animal proteins for the nutrition they need to survive. Given the importance of meat in their diet, it's not surprising that Noel and Hu found that a cat's hook-like papillae are useful in both gripping and shredding meat. This revelation might make you think twice about letting your cat lick your hand, but as long as your digits aren't made of raw meat, you should come out unscathed!

RELATED: Can Cats Eat Raw Chicken? Everything You Need to Know Before Feeding Your Feline Raw Meat

One potential downside of keeping a fine-toothed comb in your mouth is the notorious hairball. "Some cats may suffer from hairballs because their tongues grip fur so well," explains Moon. But she says that in most cases, there's no need to worry as the majority of hairballs will either pass along the gastrointestinal tract or be vomited up in due time. "Rarely, " Moon continues, "a cat will need surgery to remove a large hairball."

However, if your cat is throwing up hairballs more than once a week or you're worried that something is off, let your veterinarian know.