2018-01-17 / Columnists

Pets, Pets, Pets

Can dogs smell the passage of time? Specifically, can dogs smell when it is time for their owners to come home from work? In other words, “Does absence of scent makes the heart grow fonder?”

Dogs “smelling” time: Dogs have long been known to pick up scents humans can’t, but they may also be able to tell the time using their noses. Let’s start with one scent vs. time theory that explains how tracking dogs know which way to go when they find footprints.

Alexandra Horowitz, author of “Being a Dog: Following the Dog Into a World of Smell” and adjunct associate professor at Barnard College, has an interesting and logical explanation: “A tracking dog searching for a missing person finds footprints, but at first sniff doesn’t know which way the footprints are going. However, the dog keeps its nose to the ground and can tell the direction by detecting a difference in odor concentration at the first and fifth footstep. The first footstep will have slightly less odor than the step taken seconds later- the fifth footstep. Therefore, the dog keeps following the most recent “smelling” steps.”

Can dogs "smell" when it's time for their owners to come home? Can dogs "smell" when it's time for their owners to come home? This degree of scent discrimination is not hard for most dogs, although Bloodhounds’ noses and ear flapping make them the ultimate trackers. Many dogs can tell which way to follow a scent trail by heading from where it is weakest (oldest) to where it is strongest (most recent) when the difference is so minute. Stronger odors are often newer and weaker ones are older. When dogs smell weak odors, they are perceiving actions of the past. Dogs can detect both new and old odors, so they are sensing events and substances across time.

Dr. Horowitz leads the Horowitz Canine Cognition Lab at Barnard. Her researchers investigate the behavior and cognition of domestic dogs in their natural environments. They recruit dogs and owners to participate in fun and interesting studies, such as those looking at the use of attention and play signals in social play, dog-human play strategies, olfaction, anthropomorphisms and dog-to-dog vocalizations. They conduct studies throughout New York City, and are always looking for local dogs and owners to participate.

Dr. Horowitz’s tracking skill explanation can be expanded to clarify the claim she makes in her book of a way companion dogs sense it’s time for their “people” to return home. The dog may be waiting at the window even before the car appears in the driveway, or standing by the door before the owner starts jingling his keys.

Dogs smell the “witching hour.” For dogs, odors change over time. After you leave the house to go to work each day, the smell of you in the house decreases with each hour you’re gone. Your dog can detect the difference, and has learned through repetition when the smell of you has weakened to a specific point, you come home. Hence, the strength of your odor predicts the time of your return.

Of course, other factors come into play too. Here’s a partial list: The dog’s stomach is rumbling; his bladder is full and the amount of daylight all contribute to the internal clock that makes your best friend ecstatic moments before you have arrived home.

Dog’s nose vs. a person’s nose: A human nose contains around 5 to 6 million olfactory (smell) receptors; a dog’s nose contains from 125 million to 300 million olfactory receptors, depending on the breed. The area of a dog’s brain that processes odors is about 40 times larger than the corresponding area in the human brain (in proportion to the total size of the brain).

Dogs can detect some odors in parts per trillion. In her book “Inside of a Dog,” Dr. Horowitz writes while we might notice if our coffee had a teaspoon of sugar added, a dog can detect a teaspoon of sugar in a million gallons of water, or two Olympic-sized pools’ worth.

Research indicates it’s quite likely dogs can smell fear, anxiety, even sadness. The hormone adrenaline is undetectable by our noses, but dogs can smell it. In addition, fear or anxiety is often accompanied by increased heart rate and blood flow which rush body chemicals dogs can detect to the skin's surface.

Dogs have an additional organ in their nasal cavity known as Jacobson’s organ. This organ’s function is a combination of taste and smell. Dogs can literally taste the air. A dog experiencing this taste/smell experience usually holds his mouth in a semi-open position that resembles a grin. Scientists call this a Flehman Reaction. When Bloodhounds shake their heads, they are using their floppy ears to stir up odors near the ground and concentrate the scents near their Jacobson’s organ.

Examples where dogs are used for their incredible sense of smell:

1. USDA Jack Russell Terriers detect brown tree snakes hidden on cargo being loaded on planes in Guam.

2. US Customs and Border Protection has over 800 canine teams which look for explosives, drugs, concealed people and even hidden currency.

3. FDA Beagles check international travelers at borders and airports for agricultural contraband.

4. Dogs check packages mailed and delivered to agricultural areas for pests and their diseases which could devastate farming in that area.

5. Dogs work in IRS centers to look for explosives in letters and packages.

6. Beagles are used by some exterminators to detect termites.

7. Service dogs are being trained to alert owners to oncoming diabetic crises, epileptic seizures and other medical emergencies.

8. The University of Pennsylvania has a breeding program for dogs detecting specific cancers.

For Adoption at Babylon Shelter (631-643- 9270) Lamar St., W. Babylon: “Trudy” 8-19 is a six-month old tabby kitten with tons of "purr-sonality." “Willie” 17-690 is about 10 months and has great pup potential. He has good dog skills and a willingness to learn.

Return to top