Updated - Feb 28th, 2022
Have you ever felt awkward as your dog investigates the butt of every dog it comes across? It may be unseemly to us humans, but to dogs, it’s the official handshake taken to a whole new level of efficiency.
Humans use more subtle signs to size each other up. We look at facial expressions, handshakes, body language, small talk, and our instincts (which may not be correct). But dogs have a quicker, more efficient way of gleaning information about who they meet—they sniff each other’s butt.
Dogs can assess another dog by sniffing their butt better than we humans can assess each other through hours of conversation. But it still seems awkward, and only a few of us understand the reasoning behind it. Why is the butt so important to your pup? Let’s find out!
To understand the sniffing action, let’s look at the amazing canine nose.
A dog’s nose is its intro to the world
Depending on their breed, dogs can smell anywhere from 10,000 to 300,000 times better than humans. This is because humans have five million olfactory receptors (turbinates) and dogs have 300 million. As an example, a dog can sniff out a drop of blood from an area as large as an Olympic-sized swimming pool! Or imagine going into your friend’s house and smelling something yummy cooking in the oven. We smell the meal, but our dog’s sense of smell distinguishes the difference between the cheese, flour, tomato, garlic, basil, meats, and whatever was on the pan prior to the pizza!
A dog’s nose is actually two chambers attached to the nasal cavity. When dogs inhale through their nostrils, the scent particles or molecules get trapped by mucus in the nasal cavity. They pass through the turbinates and then transmit to the dog’s brain for processing. They use this chamber for scent molecules of environmental information.
Besides the nostrils, a dog has another chamber in the nasal cavity used for deciphering scent codes. The vomeronasal organ, or Jacobson Organ, is on the roof of the mouth (near the back). It detects pheromones that influence social behavior. You can watch a dog sniffing and see Jacobson’s organ in use by the slack jaw and mouth breathing. Cats are good ones for this; they open their mouths wider and usually look disgusted when using their Jacobson organ. That silly-looking expression is called the Flehmen Response.
Dogs use 40 times more of their brain for processing scents than humans do. Some believe that dogs can also note the passage of time through their noses. A study was done suggesting dogs know when it’s time for their pet parents to get home from the smells or movement of odors in the house. The longer the pet parent is gone, the less the odor or smell is present, meaning it must be time for them to come home now.
Pretty fascinating, but it doesn’t explain your dog’s preference of sniffing another dog’s butt.
Why the butt?
Dogs see the world through their nose and can process even the slightest changes in the air. So unlike humans, they have more efficient ways of gathering information. When we go for a walk with our dogs, they have to sniff everything to gain the low down about what’s going on around them. We talk to people, watch body language and scan our surroundings. A dog can sniff out information much quicker with intricate details!
When meeting another dog, its butt is the window to important information that determines whether that new dog is a friend or possibly a foe. The key to this information is the Anal Succules.
The dog butt contains two little sacs called Anal Succules (anal glands or anal sacs) on the inside of the anus. These are the sacs that groomers or vets will occasionally express to avoid blockages or infections. They contain potent chemical secretions of pheromones and scent molecules that provide a load of information about your dog to other dogs. And yes, they smell horrible!
But your dog, with its powerful sniffing ability, can get information about another dog by sniffing these sacs. And, interestingly, we think there’s a big poop odor back there, but your dog completely ignores that and hones into only the gland secretions.
A few well-placed sniffs communicate:
- Reproductive status
- Health status
- Emotional state
Your dog can tell if this is a friend they’ve met before or not, or, if the scent is on the ground, they can tell if that dog is nearby. It’s a biography written in scent molecules and pheromones and a prime example of chemical communication present throughout the animal kingdom.
Some info about sniffs
You may feel uncomfortable to have your dog eagerly greet another dog by shoving its nose up the other’s butt, but it’s an instinctual, necessary greeting for dogs and perfectly normal. They have taken meeting new friends to a whole new level!
However, besides getting the low down on a new friend, dogs sniff for other reasons too. For some, it’s relaxation. Smelling around is a fun and stimulating exercise to explore all the new odors in your dog’s world.
There’s also a lot of information to be figured out. Who was here, what kind of mood were they in, was it a human, a dog, a cat, a rodent? So many things your dog loves to explore!
Allowing your dog plenty of time to sniff around, or check out that cute new dog’s rear end, is an important part of dog behavior. Many dogs will be less likely to become aggressive if allowed a good sniff or two. Some dogs can be overly diligent when checking out a new friend, so be sure and watch the body language going on. That new friend may need more personal space than your dog is honoring.
Teaching your dog to sit and stay can help when socializing, just in case a good sniff greeting is unwelcome. Being able to calm or distract your dog’s exploration behavior if needed can avoid any conflicts.
A study found that male dogs do more butt sniffing in public areas than female dogs. And dogs remember the scents, so will quickly recognize their own humans or another human or dog they have previously met.
Why isn’t my dog a sniffer?
If your dog doesn’t seem interested in sniffing dog derrieres, there can be a few reasons why.
Some dogs prefer people to dogs and aren’t interested in socializing. And some may have a diminished sense of smell due to age or illness or could have had a previous trauma that caused fear or anxiety. Talking to your veterinarian about your dog will narrow down the possibilities and make sure nothing is amiss with your tail-wagger’s health.
As you can see, dogs have us humans beat when it comes to gleaning information about new acquaintances. Sniffing butts is the quickest and most reliable way for them to progress from “who are you?” to “let’s play!”
So next time you feel awkward while your dog grabs a quick sniff of another dog’s behind, keep in mind your dog is a social butterfly quickly making new friends!