Sniffing out the Facts

Categories: Dog Senses
By Amy Wence
Smell is a dog’s sharpest sense. When dogs sniff us, they can tell where we’ve been, what we’ve been doing, what we ate, and even if we are not feeling well.

A dog’s nose is up to 10,000 times more sensitive than a human’s!

Dogs have approximately 200 million scent receptors compared to our 5 million.

The bigger the honker, the better! Larger noses have more scent receptors. For example, the dachshund has about 125 million scent receptorcells, while a beagle and German shepherd dog have about 225 million. The bloodhound takes the cake with around 300 million scent receptors!!!

Each dog has an individual “noseprint,” just as humans have unique fingerprints.

Dogs interrupt their normal breathing processwhen they pursue a scent. This is why if you offera panting dog a treat, he will stop panting so thathe can turn on his smelling ability to interpret thescent being offered.

Dogs prefer to mark vertical surfaces with urine because theair can carry the scent farther if it is above ground. Also, the higher the mark, the larger the dog. Since size is an important factor for determining dominance, male dogs developed the habit of lifting their leg to aim their urine higher.

Urine marking is also a way for dogs to convey information. Dog urine contains various pheromones, which provide a great deal of information about that dog. Dogs can identify the age, gender, health, and mood of another dog just by sniffing his urine. So when you are walking your dog and he stops to sniff a tree or fire hydrant, he is getting all kinds of stimulating information. It’s a dog’s source of daily news!

Research has shown that when dogs are overheated, their ability to track and recognize items by scent is reduced by over 40%.

Dogs are able to smell multiple layers of odor and separate the smells from one another to identify each individual scent. For instance, while we may smell a pot of chili on the stove, the dog smells meat, beans, tomato, onion, and each of the spices.


Dogs do not like citrus smells like lime, lemon, and orange. Does especially dislike citronella.

Dogs are able to identify humans by their individual scent.

Dogs’ noses are so sensitive that they have even been shown to detect the presence of cancer in humans.

A dog’s nose is wet because the moisture helps to attract and hold scent molecules so they can travel through the nostrils.

Dogs can sense odors at concentrations nearly 100 million times lower than humans can. They can detect one drop of blood in five quarts of water!

“How Dogs Think” by Stanley Coren