What Makes Dogs Such Good Sniffers? This Nose-Brain Connection May Be The Reason

Dogs have been known for their smell-sensing prowess. But what makes them such good sniffers? A new study stumbled upon the answer while mapping the nerve connections in the dog brain.

A team of researchers conducted a study on 20 mixed breed dogs and three beagles. All the dogs had long noses and medium-size heads. The aim was to map neural connections and pathways with the help of a technique called Diffusion MRI. The technique involves the movement of water molecules along tissues to reveal the hidden pathways.

The results didn't come as a surprise for Pip Johnson, a veterinary radiologist and neuroimaging expert at Cornell University College of Veterinary Medicine, and her team. A dog's nose has around 200 million to 1 billion odor receptors compared to a meager five million in humans. Johnson was more interested in finding unconventional pathways than the already studied ones. And she hit the jackpot.

The MRI scans blew away the researchers as the dog brain map revealed five unique connections from the olfactory bulb – the initial recipient of smell after it enters the nose. They include the occipital lobe, cortical spinal tract, limbic system, piriform lobe and entorhinal pathway, according to the study published in the Journal of Neuroscience.

"I just kept finding these huge pathways," said Johnson. "They seem like information freeways running from the nose back into the brain."

This was the first documented connection between the olfactory bulb and occipital lobe (associated with vision) in any species.

This connection explains how dogs "see" the world with their snout. The findings suggest dogs' sense of smell is connected with their vision.

"There have been lots of people who theorized that this connection existed, based on the behavior of trained dogs and detection dogs," said Eileen Jenkins, a veterinarian at Veterinary Specialists & Emergency in Alabama, who was not part of the study. "But nobody has been able to prove it. This is fabulous."

The study offers an explanation on how smell compensates when a dog losses its vision. "Blind dogs can still play fetch," noted Johnson.