What Is 'Normal' for a Dog?

From chasing their own tails to humping your leg, dog behaviors can seem downright weird - if you happen to be human. Many quirky habits are normal in dogs, though a few may suggest hidden medical problems. To learn the difference, WebMD turned to Pamela Reid, PhD, vice president of the ASPCA's Animal Behavior Center. In the following slides, Reid decodes a range of puzzling canine customs.

Crotch-Sniffing

Dogs like to sniff each other's bottoms, but what about a pooch nosing up to a human crotch? That's just bad manners, right? Not according to the canine code of conduct. "Dogs can tell an enormous amount of information about other dogs by sniffing the genital area," Reid says. "There's good reason to think they get this information [by sniffing] people, too." If your dog's nosey nose mortifies your guests, obedience training may help.

Tail-Chasing

When puppies chase their tails, it's like babies grabbing their toes - a way to explore their bodies. "It's only a problem when dogs become compulsive about it," Reid tells WebMD. "The litmus test is whether or not you can distract them." If your dog would rather chase its tail than eat or go for a walk, it's no longer fun and games. Compulsive disorder is common in certain breeds. It can be treated with behavior modification and medication.

Scooting

It's common for dogs to scoot or drag their bottoms across the ground after doing their business - particularly if their stool is loose. But if a dog scoots frequently throughout the day, Reid recommends an immediate trip to the veterinarian. Scooting is often a sign of impacted anal glands, a condition that can have serious complications if left untreated.

Humping

Watching your dog get personal with the new sofa may make you cringe, but it's not abnormal. Many dogs discover that humping feels good or relieves stress, so they keep at it. Both males and females are known to indulge in this behavior, though males do it more often. Reid says it's fine to look the other way in most cases. "But if they're humping family members or guests who come to the house, behavior modification is in order."

Reverse Sneezing

Sometimes your dog may make a loud snorting or inhaling sound that's best described as reverse sneezing. During a reverse sneeze, which usually lasts about a minute, your dog may stiffen his stance and extend his head, and his eyes may bulge. Although the episode may be unnerving, it's usually caused by something harmless, such as leash pulling or excitement. Massaging your dog's throat, offering him something to lick, or placing your fingers over his nostrils may cause him to swallow, which may stop the sneeze. But check with your veterinarian if it happens often. It may be a sign of allergies, mites, infection, foreign body, or another medical condition.

Eating Grass

Your lawn may not look like a gourmet meal to you, but your dog has other ideas. Canines are omnivores, Reid explains, meaning they like vegetation in addition to meat. Eating grass, sticks and even dirt is normal - in moderation. If your dog binges on grass, it may be a sign of an upset stomach.

Eating Excrement

It's "surprisingly normal" for dogs to eat excrement, Reid says. It's part of their evolution. "In the early domestication stage, dogs performed a hygienic function - cleaning up feces. Their digestive system is very efficient, so they can get some quality nutrients out of it." However, most people don't want kisses from potty-mouthed dogs. If you catch your pooch in the act, offer tastier food as a distraction.

Rolling in Garbage

If you see a decaying animal or a pile of garbage, your instinct is to step around it - but your dog's greatest desire is to roll in it. The more foul the smell, the stronger the lure. One theory is that dogs like to cover their own scent with horrible odors to make it easier to surprise prey. You probably can't curb your dog's interest in this pastime, so your best hope is to spot smelly things first and steer your pal clear.

Drooling

If your dog salivates when you're grilling steaks, that's as it should be. But drooling throughout the day is not normal, Reid says. Excessive drooling may signal a wide range of medical problems, including illness or a reaction to something in the environment. If it occurs with behavioral problems, such as chewing or hiding, drooling can also be a symptom of anxiety. In short, an abundance of dog drool warrants a trip to the veterinarian.

Herding

Some dogs will try to herd anything - cats, ducks, even your kids. "They were bred to do this," Reid explains. "They naturally want to move things around, collect things, stop the chaos. It's a behavior they desperately need to express because everything in their genetic makeup is telling them to do this." While the behavior is not abnormal, it can become problematic. With training, dogs can learn to herd only when appropriate.

Noise Phobia

Dogs that cower in the corner at every crack of thunder could be suffering from a noise phobia. Other common triggers are sirens and gunshots. Noise phobias can be severe and difficult to treat. "Many people wait too long for help," Reid says. Through conditioning programs, such as engaging in positive activities during recordings of thunderstorms, dogs can learn to relax when they hear upsetting sounds.

Paw-Licking

Dogs lick their paws as part of their normal grooming behavior, Reid explains. But if your dog licks so much that the paws lose hair, become discolored or develop open sores, there is clearly a problem. The top causes of excessive licking are yeast infections and skin allergies. In some cases, licking can be a compulsive behavior. But it's important to see the veterinarian and rule out medical issues before reaching that conclusion.

Glow-in-the-Dark Eyes

No, your dog is not possessed. Canine eyes naturally glow in the dark to varying degrees, because their structure differs from that of human eyes. Dogs have a layer of tissue called the tapetum lucidum, which reflects light back through the retina. This is one reason canines have better night vision than people do.

Dreaming

Your dog is curled up in bed, eyes shut and paws twitching. Every now and then, a soft whine or yowl breaks the silence. You would swear Rex is dreaming. You're probably right, Reid says. "If you look at a dog's brainwaves during sleep, they appear to have REM cycles." REM or rapid eye movement is the stage of sleep during which humans tend to dream. So what do dogs dream about? That's one secret our four-legged friends get to keep.

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