Pet Connection

Rough Side of the Tongue?

The spines on a cat’s tongue serve a variety of purposes

By Kim Campbell Thornton

Andrews McMeel Syndication

If you’ve ever been licked by a cat, you know the rough feel of the tongue, lined with rows of backward-facing barbs called papillae.

It used to be thought that papillae were in the form of a solid cone, but engineering researchers at Georgia Tech took a closer look and made a surprising discovery. Using 3D scanning with micro-computed tomography, the actual shape of the small spines was revealed to be not conical, but hollow. And that shape has a specific purpose.

“I liken them to ice-cream scoops,” says Alexis C. Noel, lead author of a paper published last December in the peer-reviewed scientific journal Proceedings of the National Academy of Sciences (PNAS). “They have this little U-shaped hollow from the tip down. We found that this cavity holds fluids really well.”

To test the action of the papillae, Noel and co-author David L. Hu introduced drops of food dye to the tip of the spine. “It sucked it up like a straw,” she says.

The scoop shape enables cats to use surface-tension forces to pull up water as they lap it, as well as to wick saliva deep into their fur, a way of cooling themselves.

“This shape makes much more sense, from a biomechanical standpoint,” says feline veterinary specialist Drew Weigner, DVM, who practices in Atlanta and is president-elect of the Winn Feline Foundation.

The investigation was inspired by Noel’s own cat, who was sitting on her one day while she watched TV.

“He decided to lick this microfiber blanket that he was on top of, and he got his tongue stuck in it,” she says. “I had to detangle him from the blanket, and it made me think. Everybody says cat tongues are kind of like sandpaper, but it really looks like the tongue is a lot more like Velcro.”

She and Hu hypothesized that when cats lick themselves, saliva -- containing enzymes that break down fats and particulates -- is distributed from the hollow spines, all the way down to the root of the hairs. They used high-speed videography to film three adult cats grooming themselves. During grooming, papillae become erect, increasing their contact area with fur. This contributes to saliva’s cooling effect.

Cats don’t have sweat glands over their bodies, except on their paws, so the thorough distribution of saliva helps to remove heat from the skin. Without papillae to push saliva deep into the fur, it would wet only the top layer of hairs.

The spines also help cats lick up oils, dirt, blood, feces and other contaminants. This not only keeps cats clean, but it also reduces odors that might otherwise expose their presence to predators.

Beyond domestic cats, Noel and Hu were able to examine the tongues of five other members of the feline family: bobcat, cougar, snow leopard, tiger and lion. What they found surprised them: Papillae are the same size and shape regardless of species.

That means the papillae of your tabby or tortoiseshell are just like those of a tiger or lion -- except the big cats have more of them. Cats have about 300 papillae, while tigers have approximately 1,200.

“We thought that was strange because generally when you go from a small species to a large species, these things tend to scale, but these papillae didn’t,” Noel says.

On further investigation, they learned that no matter what the species, feline papillae are almost always long enough to penetrate fur and reach the skin. The exception is the Persian, with long, thick fur that’s impenetrable. “With these cats, the cat physically cannot push the tongue spine through the fur and reach the skin,” she says.

Q&A

Vomiting has

many causes

Q: I took my dog out to potty, and a few minutes later he started hacking and vomiting up clear liquid. I don’t know if it was caused by something he ate outdoors, the half a pear core he had eaten a few hours earlier (and eventually vomited back up) or the antibiotic he started taking last night.

He seems fine now, but how do I know when vomiting is an emergency?

A: Dogs can throw up easily and for any number of reasons. Sometimes it’s because they get into the garbage or eat something they’re not used to (that pear core, maybe). They may down something disastrous, like rat poison or some other toxin. Internal parasites, certain diseases, stress and, yes, certain antibiotics can all cause your dog to upchuck.

Oftentimes, a dog’s stomach upset is the result of dietary indiscretion, but I never like to assume that. Foreign-body obstruction, ingestion of a rodenticide and bloat are all emergencies that can have fatal (or at best, expensive) results if you wait too long to treat them.

Call your veterinarian and describe what’s happening. The history of the problem gives your veterinarian clues as to whether the problem is urgent.

How do you know if a case of vomiting warrants a visit to the veterinarian? Puppies (and kittens), toy dogs and older animals are more prone to dehydration and may benefit from subcutaneous fluids, so it’s best to take them in sooner rather than later.

Other causes for concern are an increase in the volume or frequency of vomiting or diarrhea; the presence of blood in the vomit or vomit that smells like feces; and persistent retching without bringing anything up, which could suggest bloat. Take your dog in right away if he shows any of these signs. -- Dr. Marty Becker

Do you have a pet question? Send it to askpetconnection@gmail.com or visit Facebook.com/DrMartyBecker.

THE BUZZ

Check calendar for

dog and cat days

-- May is an eventful month for pets. Take time out to observe Pet Cancer Awareness Month, National Pet Month, Be Kind to Animals Week (May 5-11), National Animal Disaster Preparedness Day (take a pet first-aid class or set up a "go bag" with everything your pet might need if you have to evacuate on May 11), International Chihuahua Appreciation Day (May 14), World Turtle Day (May 23) and International Hug Your Cat Day (May 30). Cats don’t especially enjoy being hugged, so maybe just give her a good scratch behind the ears.

-- Which is cleaner, your dog’s fur or your husband’s beard? Swiss researchers found that dog fur wins out. They swabbed the beards of 18 men and the necks of 30 dogs of assorted breeds and compared the results. All the men had high bacterial counts in their beards while only 23 of the dogs (76 percent) had the same result. The remaining seven dogs had medium-to-low levels of bacteria. Maybe it’s time to retire the phrase “You dirty dog!”

-- If you have a new kitten, be sure she is properly vaccinated. Current recommendations are an initial inoculation for feline viral rhinotracheitis, calicivirus and panleukopenia when kittens are 6 to 8 weeks old, followed by additional doses every three to four weeks until the kitten is 16 to 20 weeks old. A single, separate rabies vaccine can be given when the kitten is 12 to 16 weeks old. Even if your locale does not require cats to be vaccinated for rabies, it offers important protection in case your cat ever encounters a rabid animal. Bats can fly into homes, and it’s not uncommon for cats in their own yards to come in contact with skunks and raccoons, which often carry rabies. -- Dr. Marty Becker, Kim Campbell Thornton and Mikkel Becker

ABOUT PET CONNECTION

Pet Connection is produced by a team of pet-care experts headed by "The Dr. Oz Show" veterinarian Dr. Marty Becker and award-winning journalist Kim Campbell Thornton. They are affiliated with Vetstreet.com and are the authors of many best-selling pet-care books. Joining them is dog trainer and behavior consultant Mikkel Becker. Dr. Becker can be found at Facebook.com/DrMartyBecker or on Twitter at DrMartyBecker. Kim Campbell Thornton is at Facebook.com/KimCampbellThornton and on Twitter at kkcthornton. Mikkel Becker is at Facebook.com/MikkelBecker and on Twitter at MikkelBecker.

More like Pet Connection