We are all aware of the incredible abilities of the canine nose. But how do dog nostrils work? Have you ever paid attention to your Labrador’s nostrils?
Researchers from the University of Bari and the University of Trento in Italy want to know how dog nostrils work so they videotaped a number of dog noses and then analyzed their nostril activity frame-by-frame.
The research was conducted by Marcello Siniscalchi and his team! Using cotton swabs with different odors, the researchers examined whether dogs use a particular nostril – right or left – when smelling different scents.
While there are many ways to distinguish how dogs interpret different stimuli, the nostrils could provide further insight.
The researchers presented 6 different scents to 30 mixed-breed dogs a number of times.
The scents were chosen because they varied “in terms of familiarity and emotional valence” and included some things dogs typically get excited about.
The six odors were the scent of:
- dog food
- vaginal secretions from a healthy female dog in oestrus
- a swab with nothing on it
- sweat from a known veterinarian
Here’s the logic behind the choices:
- Dogs are naturally interested in the first two odors and find them non-threatening.
- The middle two are neutral.
- The last two have the potential to make dogs feel alarmed or anxious.
The dogs smeed these scents over the course of a few weeks.
When the dogs were presented with the potentially noxious stimuli (the vet and the adrenaline), they “showed a consistent right nostril bias.” This means they started investigating with the right nostril and stayed investigating with the right nostril over the next presentations.
When the dogs were presented with potentially non-threatening stimuli, like the food and the vaginal secretion, they initially investigated with their right nostril and then shifted to their left.
Although this research is in its infancy, this difference in nostril use is something to take note of and consider as it could indicate something about a scent’s valence –whether novel or familiar; positive or negative— as well as how scents are processed in a dog’s brain.
According to 2004 research by Royet and Plailly, “In mammals, the olfactory system ascends mainly ipsilaterally, with most receptor information from each nostril projecting, via the olfactory bulb, to the primary olfactory cortex in the same hemisphere.”
This essentially means that what goes in the right nostril is being processed on the right side of the brain, and what goes in the left nostril goes to the left side.
Lateralization research suggests that the brain’s right hemisphere is often involved in investigating novelty and is also associated with “intense emotions, such as aggression, escape behavior and fear,” while the left hemisphere focuses on routine investigation and categorization, positive emotional valence, and approach behavior.
The study’s findings are consistent with those general principles. Dogs tended to start their investigation with their right nostril (novelty), and they proceed to investigate the potentially arousing stimuli — like the vet odor and adrenaline — through the right nostril. But with repeated presentations of non-aversive stimuli — like the food and smell of another dog — dogs switched to the left nostril.
Image sources: Desha Tennakoon/Facebook, Scientific American
Source: Scientific American