Why do cats and dogs rub their butts on the floor?

Dogs and cats are cute, playful, lovable… and extremely gross. Besides eating poop and licking their butts, one of the most bizarre things these pets can do is rub their rumps on the floor.

But why do dogs and cats do this "butt scooting?"

Pets rub their butts on the floor simply because it's the easiest way to itch them, said José Arce, president of the American Veterinary Medicine Association. Just like humans, pets sometimes get itches on random parts of their bodies. And when a pet's butt is itchy, dragging it across the floor is the easiest way to scratch it.

Related: Why do dogs and cats run around in random bursts of speed?

Sometimes the itch and subsequent butt scoot is a one-off thing. Other times, particularly when it occurs more frequently, butt scooting can be a sign that your cat or dog is experiencing a medical issue. "It's kind of humorous; it looks like boogying or dancing. But actually, it means they're irritated," Arce said.

One trigger for butt scooting is irritated anal sacs. The anal sacs are two small glands on either side of a cat or dog's anal opening. Experts aren't entirely sure what their purpose is, Arce told Live Science, but some ideas are that the smelly fluid the glands release lubricate and scent their feces, mark territory or attract a mate. In dogs, it's relatively common for the sacs to become infected or blocked up, though less so in cats. An affected animal may butt scoot due to the irritation, potentially leaving behind feces or blood.

When fully blocked, the anal sacs can swell, and they may eventually burst. It's best to bring your pet into the vet before this happens so they can express the anal glands, clearing out the blockage — and ending the irritation and butt scooting.

Another common cause of butt scooting is intestinal parasites. Pets can't feel the parasites throughout most of their intestines, but they may be able to feel them wriggling near the anus. Any type of intestinal parasite can cause itchiness and lead to butt scooting, but Arce has found that it's especially common with hookworms and tapeworms. If a pet does have a parasitic infection, veterinarians can diagnose them with a fecal test and provide deworming treatment.

Allergies and fleas can also cause irritation that leads to butt scooting. In these cases, the pet will often also scratch other parts of their body, such as their ears. And after grooming, a dog may temporarily butt scoot because their freshly trimmed tissue is sensitive.

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But butt scooting can also be a sign of a larger issue, such as a tumor of the anal sac. This is rare in cats but does occur, Arce said. It can occur in any dog breed, but is more common in spaniels.

If your dog or cat is butt scooting more than occasionally, Arce recommended taking them to the vet pronto to diagnose and treat the issue. Besides, whereas a person will likely stop scratching an itch if they begin to hurt themself, an animal may not, and they could even scoot until they ulcerate their skin.

"You might think butt scooting is humorous, but it's a sign of discomfort," Arce said. "If it repeats, see a vet, because we can diagnose the issue pretty quickly and easily."

Originally published on Live Science.