We’ve all seen dogs do it.  When canines approach each other, they often walk right up the other dog’s rear end at the first meeting.  To a human, nothing seems stranger or more distasteful than the idea of taking a nice long whiff of another being’s behind. But to a dog, this is not only a natural instinct, it is one of the best ways to learn a whole host of facts about this new pal.  Here are some facts about a dog’s anal glands, and what possesses dogs to sniff one another.

What is the benefit of sniffing?

Every dog has two anal glands located just on the inside of the anus, where they store liquid. Every time the dog eliminates waste, the grape-sized glands excrete a minor amount of the fluid onto the feces, which identifies it as the individual dog’s waste. This is what many people refer to as “the calling card” or “marking the territory.”

While humans find the odor unpalatable, dogs can absorb an abundance of information from the scent. Every dog’s gland secretion is created with a concoction of original elements of aliphatic acid, ethanol, acetic acid, and trimethylamine. These combined provide information about what the dog eats, where he has been, how old he is, whether or not he is ready to mate, etc.  Sniffing another dog’s behind could be equated to reading an online profile about someone, or looking at their driver’s license.  Dogs are able to learn all of this information about other pups that a mere glance of the eyes would never be able to reveal.

Not just sniffing… (Other uses for anal glands)

Though the primary purpose of a creature’s anal glands are to mark territory, and identify the dog when pups sniff each other,  there are other uses for the glands as well.  When agitated or frightened, a dog might release all the fluid in the glands as a defense mechanism.  Not unlike the skunk’s main weapon, doing so will cause a brief diversion of a strong and putrid odor that could allow the dog a chance to get away.

Other behaviors are associated with the anal glands as well, such as “bottom dragging.” When an animal’s anal glands become too full, or blocked up for some reason, you may witness the dog dragging his behind on the floor as a well of expelling some of the liquid. Because anal glands can experience swelling, causing the dog or cat discomfort, one of the best ways to help the sacs become healthy and functional again, is to have them expelled by the groomer or veterinarian.  Doing so will restore the glands, allowing the animal’s body to function properly again.