The Sensory Acuity of Japanese Dogs

Dogs’ olfactory acuity is remarkable. Below are several anecdotes and observations that illustrate this.

1. Olfaction: The Power to “See” the Unseen

A man was living with a seven-month-old Kishu puppy. When he plucked a small amount of hair from another Kishu living in the same household and buried it at the base of some tall grass, the puppy quickly sniffed it out and picked it up. Even when the hair was reburied elsewhere, the puppy again located and retrieved it. It is fair to say that dogs can apprehend the presence of invisible targets through smell. By relying on scent differences imperceptible to humans, dogs perceive the world in a far broader way.

2. Adaptation in a Visually Impaired Wolf Pup

The next case concerns four Arctic wolf pups (two males, two females) that were hand-reared from 42 days of age. One female, born at the Berlin Zoo, lost her sight due to optic-nerve damage sustained when she fell into a trench about four meters below the den. Veterinary behavioral observation and specialist examination confirmed that vision had already been lost at 42 days of age.

Although the female pup was completely blind by nine weeks, when walked on a lead she was able to stop just before moats and obstacles. After a further four to five weeks, she learned to avoid puddles and negotiate obstacles such as trees, and exhibited adaptive changes in gait such as lifting her legs higher. To observers unaware of her condition, her behavior looked so natural that she was scarcely distinguishable from her littermates.

However, she was clearly disadvantaged in pursuit of prey. When a chicken was released in front of the four, the sighted littermates immediately gave chase, whereas the blind pup could not pursue it. This suggests that vision is indispensable for certain components of predatory behavior.

3. The Informational World Afforded by Smell and Hearing

The keenness of canine olfaction and audition is often described in legendary terms. Exactly what concentration differences they can discriminate, and what kinds of acoustic contrasts they can detect, depends on conditions; nevertheless, it is reasonable to think that olfactory and auditory channels deliver information to the canine brain that humans cannot access, and that dogs use this to guide behavioral decisions.

A common trope assigns 87% to vision, 7% to hearing, 3% to touch, 2% to smell, and 1% to taste in terms of the “contribution” of the five senses. In practice, these proportions depend heavily on context and task design. It is prudent to treat such figures with caution rather than as universally applicable constants.

4. Cases: Cues from Sound and Scent

・Sound (hearing): Some dogs can recognize their owner’s car well in advance by using pattern differences in the sound of approaching vehicles. Depending on environmental noise and wind conditions, some will respond hundreds of meters away.

・Scent (smell): Dogs may discriminate the smell of water and rotting wood, and use differences between the odors of rock and surrounding soil or vegetation to pinpoint locations. They likely integrate tactile input from the paw pads and skin as well, combining multiple senses to model their environment.

Dogs apportion their senses with weights different from those of humans andrely especially on smell and hearing as their primary means of explorationto interpret the world. Even when visual information is limited, they can optimize behavior through theintegration of olfaction, audition, and touch—a flexible sensory strategy that is a major strength of the species.