It can be embarrassing when you run into a neighbor while you’re both walking your dogs and all your dog wants to do is smell the other dog’s butt. Relax a little; that’s normal dog behavior. If you pull on the leash to get your dog to stay away from the other dog’s butt, you might cause a fight to break out: by pulling your dog, you might make him look threatening to the other dog.
Humans can’t completely understand all the information a dog gets from smelling another dog’s butt. At least 33 percent of a dog’s brain is designed to process smells, as opposed to about 5 percent of a human’s brain. A dog’s sense of smell is so powerful that he can tell, for example, whether the dog before him in the veterinarian’s examination room was afraid, just by the smell the previous dog left behind.
Dogs sniff butts to greet each other, much as humans do by shaking hands. Dogs have anal glands just inside their rectums, which produce a strong odor. Dogs can find out all sorts of information just by getting a whiff back there. They can find out the sex of the other dog, whether the dog is in heat, what the dog ate lately and whether the encounter is likely to be a friendly one. Because the smell is unique to each dog, butt sniffing is the best way dogs have to identify each other.
When a dog already knows about the other dog from a prior sniffing, he still smells the other dog every time they meet. Two dogs who live together typically smell each other’s butts when they come in from outside. So butt sniffing has another purpose: it’s also a dog calming mechanism, according to Kevin Behan, a Vermont dog trainer and author. Anytime something new happens—especially something stressful—dogs tend to sniff each other’s behinds. It satisfies the urge to do something, and it grounds them.
Some dogs, when meeting another dog for the first time, are enthusiastic sniffers. But the dog being sniffed might not take too kindly to all that focused attention. Whenever your dog is meeting another dog, be attentive. If the butt smelling is an unwelcome gesture, it’s time to separate the dogs.
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