Category Archives: Dog’s Physiology

A Dog Nose is Even More Powerful Than You Think

I love to go on walks with my dog,  but Apollo and I have very different ideas about what the point of a walk should be. I am out for exercise with a side of sunshine and fresh air. Apollo’s goal is to smell… absolutely everything! This leads to conflict. I want to keep moving and Apollo wants to stop, and then walk, and then stop, and then walk…

We all know that a dog’s sense of smell is better than our own, but do you know just how much better? I recently watched a TED-Ed Lesson that starts with an excellent explanation of just how a dog’s nose works:

As your dog catches the first hints of fresh air, her nose’s moist, spongy outside helps capture any scents the breeze carries. The ability to smell separately with each nostril, smelling in stereo, helps to determine the direction of the smell’s source so that within the first few moments of sniffing, the dog starts to become aware of not just what kind of things are out there but also where they’re located.

As air enters the nose, a small fold of tissue divides it into two separate flows, one for breathing and one just for smelling. This second airflow enters a region filled with highly specialized olfactory receptor cells, several hundred millions (300,000,000) of them, compared to our five million. And unlike our clumsy way of breathing in and out through the same passage, dogs exhale through slits at the side of their nose, creating swirls of air that help draw in new odor molecules and allow odor concentration to build up over multiple sniffs.

But all that impressive nasal architecture wouldn’t be much help without something to process the loads of information the nose scoops up. And it turns out that the olfactory system dedicated to processing smells takes up many times more relative brain area in dogs than in humans. All of this allows dogs to distinguish and remember a staggering variety of specific scents at concentrations up to 100 million times less than what our noses can detect. If you can smell a spritz of perfume in a small room, a dog would have no trouble smelling it in an enclosed stadium and distinguishing its ingredients, to boot.

The video goes on to talk about how our sense of sight and hearing present us with a picture of a single moment in time, while a dog can smell “an entire story from start to finish.” It also explains how the canine vomeronasal organ lets dogs “identify potential mates, distinguish between friendly and hostile animals, and alerts them to our various emotional states. It can even tell them when someone is pregnant or sick.”

I had reached what I thought was a pretty good compromise with Apollo on our walks. He got to dawdle at the beginning, but at all other times he was expected to get his nose off the ground and keep up the pace. Now, I think I’ll give him a few more opportunities to stop and smell the roses, so to speak.

Take a look at this TED-Ed Lesson; it will give you a new appreciation for what your dog can do with his nose.

Dr. Jennifer Coates

Diana Ruth Davidson, Chief Pet Officer and Managing Nanny, Westside Dog Nanny

We offer pet services such as:  Pet Sitting,  In-Home Dog Boarding, Dog Walking, Overnights in your home, Doggie Day Care.
310 919 9372

Are All Dogs Color Blind?


Dogs can perceive color, but their spectrum contains a lot fewer hues than what humans see.

Scientific research progresses in small increments with a lot of digressions. But many news organizations would rather have a story of some great big sudden breakthrough, and the news media tends to have a short memory. That is why we get a human interest story every few years that is all about some scientist as “discovering” that dogs are color-blind. Not completely color-blind, mind you, but red-green color-blind. In humans, this is usually described as protanopia.

Most mammals have protanopia, so it is not the red color of the cape that attracts the bull’s attention. Many insects cannot see red but can perceive ultraviolet. Humans, some other primates, fish, and birds have trichromatic vision. Some birds may have one or even two more color receptive cells than us, and so see colors and shades we cannot even imagine.

So dogs can see yellow and blue, but no green or red or colors created by these shades, such as pink, orange or purple. Or, more accurately, the color they see will be a shade of blue or yellow rather than the color that you see. If you look at the rainbows below, you see that for dogs, purple loses its red hue and becomes blue. Red becomes a murky shade of yellow mixed with dark grey.

The trichromatic spectrum
The canine visual spectrum

It is strange to look at the array of dog products in the stores, or the dyed shades of kibble, and realize that very little of this is done for dogs’ benefit. Almost all products designed for dogs seem to really be tailored to the owner, right down to color. In fact, as many as eight percent of men have some form of color-blindness, too, so it surprises me how little it is considered in the design process, from red-green traffic lights to sports team colors.

However, knowing the colors your dog can see can help you create an environment you dog can easily understand and enjoy. There are a few basic rules. If you are using color to create contrast, stop and think about how it will look to the dog.

What looks like yellow and blue to you, looks like yellow and blue to a dog. So if you want to provide color contrast and have an environment that looks similar to you and your dog, this is the color pallet is what you should use. (Even then the exact shades and their meanings are still going to be different for a dog).

If you want to assess how something might look to your dog, there are a range of filters that can give an estimate. There is an iPhone app called the Chromatic Vision Stimulator by Kazunori Asada. If you select “P” mode, you can use the phone’s camera to see a simulated protanopian view of the world. The pictures below show a few of Vera’s favorite things as they look to me and as they might look to her. It is pretty obvious that I was not thinking about dog color vision when I made some of these selections.

Vera’s things as I see them
As Vera might see them (filter via the Chromatic Vision Stimulator)

When you do this you can see that red and green objects can still present a color contrast. A red bag on a blue blanket can still be clearly seen as a kind of yellow-brown against the blue. If in doubt, it is a good idea to provide other sources of contrast, such as pattern, texture or smell, to ensure your dog can easily find his things.

Recent research showed that while dogs certainly can discriminate objects by color, when they cannot tell the colors apart they fall back on using bright versus dark as a cue. For example, a red toy on green grass might be only slightly different kinds of brownish yellow to a dog; a bright white toy will be much easier to find. There is a reason why tennis balls are bright yellow and golf balls are white. Even to the human eye, brightness makes these balls easier to see against grass, which is generally a medium to dark shade.

If you have a bed you travel with, to give your dog a “home base,” it can be good to make this as easy to find as possible. A strong pattern, plush texture, and even a non-toxic herb sachet sewed inside can make the bed easy to locate no matter where you travel and give any hotel or guest bedroom a reassuring piece of home.

And in case you think we should feel sorry for dogs not seeing all the colors we do, it all probably evens out or perhaps goes somewhat in the dog’s favor. They can hear ultrasound. They can follow a smell map or even diagnose cancer by scent. The richness of their sensory world holds pleasures we cannot even imagine, any more than we can know all of the colors that the honey-bee can see.

by Emily Kane

Diana Ruth Davidson, Chief Pet Officer and Managing Nanny, Westside Dog Nanny

We offer pet services such as:  Pet Sitting,  In-Home Dog Boarding, Dog Walking, Overnights in your home, Doggie Day Care.
310 919 9372