By Claudia Bensimoun

First published: USDAA | World Cynosport Rally February 20, 2014

Updated: 2025

Dog behavior expert and writer Claudia Bensimoun reviews new research showing that dogs perform scent-detection tasks more accurately after breakfast. Learn how glucose, ketones, and meal timing influence canine cognition and working-dog performance.

Dr. Holly Miller investigated whether a dog’s consumption of a morning meal would affect search accuracy on a working memory task following the exertion of self-control.

Image credit: Claudia Bensimoun

For centuries, dog handlers have used dogs’ exceptional scenting abilities to make the world a better place. Searching out explosives, detecting pests, and alerting children with peanut allergies are just some of the ways humans have put canines to work. Many people find it easy to accept that nutritional factors can influence brain function in dogs. Now there is solid evidence that breakfast plays a vital role in the search performance of trained canines.

Studies at the University of Kentucky suggest that eating a morning meal increases search accuracy in dogs. Dr. Holly Miller and colleague Charlotte Bender tested the search performance of trained domestic dogs after either consuming breakfast or fasting. Earlier studies demonstrating that children perform better on cognitive tasks after breakfast led Dr. Miller to wonder whether breakfast would also improve dogs’ performance.

This study focused on a dog’s accuracy in finding hidden food and investigated the effect of breakfast on a dog’s performance. The dogs were shown a treat that was then hidden in one of six containers. The results were eye-opening.

You may think that the dogs that were fasting would have retrieved the food first, since they would be hungrier. However, dogs that had already eaten breakfast 30 minutes earlier showed greater search accuracy. The study found that dogs that searched 30 minutes after a meal were more accurate than those canines that searched when hungry.

An earlier study by Dr. Miller found that exerting self-control depletes dogs’ energy levels and their ability to perform specific tasks. To ensure that all the canines tested had somewhat depleted energy levels before the search test began, the dogs had to show self-control for ten minutes by completing a sit/stay exercise.

Researchers considered these results supportive of the theory that children perform better on cognitive tasks when they have eaten breakfast. But is the same true for their wild relatives, the closely related wolves, coyotes, and jackals?

“When wolves, coyotes, and jackals eat a diet that is rich with carbohydrates, such as in commercial dog food, their brains are more dependent on glucose and more affected by fluctuations in glucose levels.

But with a diet of hunted meat, where the carbohydrate level is low but fat content is high, the brain switches to its secondary fuel source of ketone bodies instead of the preferred glucose,” Dr. Miller explains in an interview with BBC Nature.

Three water-soluble compounds, known as Ketone bodies, are produced as by-products when fatty acids are broken down for energy in the liver. Two of these ketone bodies serve as energy sources for the heart and brain. The third is excreted from the body. In the brain, ketone bodies are an essential energy source during fasting.

Image credit: Claudia Bensimoun

A dog’s brain gets some of its energy from ketone bodies when glucose is less available, as in times of fasting, strenuous exercise, or a low-carbohydrate diet. When blood glucose is low, most other tissues have additional energy sources besides ketone bodies, such as fatty acids, but the brain does not. When a dog’s diet is changed to lower blood glucose for 3 days, the brain gets 25% of its energy from ketone bodies.

Then, after the fourth day, this will increase to 70%. Nonetheless, during the initial stages, the brain does not burn ketones because they are an essential substrate for lipid synthesis.

“If these animals are consuming a natural diet that is not scavenged from the dump, they are probably in a state of ketosis where energy for neural processes does not fluctuate much.

This means that one small meal may not have a significant effect on problem-solving and may make wolves and coyotes less impulsive and more cautious in their decision-making, since their brains are already fueled steadily by ketone bodies rather than relying on glucose spikes.”

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