The effects of exercise and diet on olfactory capability in detection dogs

Abstract

A previous work suggests that dietary fat may influence canine olfaction. The present study evaluated whether olfactory performance could be influenced by forms of dietary fat and exercise. Seventeen certified detection dogs were fed three different diets (high fat, low fat or high polyunsaturated fat) for 12 weeks. After 12 weeks, olfactory testing was performed using a scent wheel in an olfaction laboratory using three explosive materials. The dogs completed eight to twelve scent trials before and after a 30 min treadmill exercise on five consecutive days. A mixed-effect logistic regression model was used to examine how diet, pre- or post-exercise, trial number, odourant, mass of target and target position influenced the probability of dogs alerting on the target odour. There were no significant changes in the dog's ability to find a target odour at threshold amounts. Dogs were 1·42 (1·08, 1·87; 95 % CI) times as likely to find a target on the high polyunsaturated fat diet relative to the high-fat diet (P = 0·009). The low-fat diet was not significantly different from either the high-fat diet or the high polyunsaturated fat diet (P = 0·12). Dogs were 1·49 (1·26, 1·76; 95 % CI) times as likely to find a target prior to exercise relative to after exercise (P < 0·001). Dogs on the high PUFA diet utilising maize oil showed mild improvement in olfaction. The exact reasons are unknown; however, the higher relative amount of linoleic acid in the diet may play a role in olfactory sensation which warrants further examination of optimal diets for detection dogs.

The Effects of Varying Concentrations of Dietary Protein and Fat on Blood Gas, Hematologic Serum Chemistry, and Body Temperature Before and After Exercise in Labrador Retrievers

“…The rooms where the dogs ran were kept at 30% humidity and 72°F at all times. All data and sample collection occurred on day 3 of the 3 days of treadmill testing on week 12, while olfaction data were obtained on the other 2 days of exercise ( 13 ).…”

“…These findings are similar to rodent studies which suggested that polyunsaturated fatty acids may affect olfaction positively by altering the olfactory bulb cellular constitution, thereby enhancing neuronal signaling ( 11 , 12 ). More recently, our lab reported that the use of corn oil improved the olfactory acuity at threshold concentrations in trained detection dogs showing that dietary fat and fat source can play a role in olfaction and/or cognition, yet the physiology of such improvements can only be speculated ( 13 ). Theoretically, dietary fat may offer an advantage of running with more thermodynamic efficiency compared to a higher protein, higher carbohydrate diets since there is less of a need for gluconeogenesis during exercise eliminating protein as a source of energy which is thermodynamically less efficient than fat or carbohydrate ( 6 ).…”

“…Contradictory results suggest that glucose helps decrease thermal load by improving respiratory dynamics and loss of heat through panting ( 14 ). Based on contradictory theories, our objectives were to utilize the same Labrador Retrievers used in our previous olfaction study, to examine the effects of diet and exercise on serum lactate, blood gases, cortisol response, complete blood counts, serum biochemistry, and body temperature (rectal and core body temperature), to better understand the physiology that might explain enhanced olfaction when fed a corn oil-supplemented diet ( 13 ). Seventeen detection dogs on two standard commercial dog foods that consisted of either low fat (LF – 27% ME protein, 32% ME fat) or high-fat performance diet (HF – 27% ME protein, 57% ME fat); as well as a low protein food with high fat made through top dressing a typical adult maintenance diet with corn oil (CO – 18% ME protein, 57% ME fat) in a cross-over design before and after exercise.…”

Drug Contamination of U.S. Paper Currency and Forensic Relevance of Canine Alert to Paper Currency: A Critical Review of the Scientific Literature

“…Currently, there is insufficient knowledge to ascertain if the probability of canine alert to currency is determined by total chemically extractable cocaine on a bill or limited to superficial cocaine that can be removed by physical means such as vacuuming. With regard to interpretation of a particular canine alert based upon extrapolation from published studies, it is important to consider biological, behavioral, and environmental variables such as breed, training, drug type, search environment, handler cues and handler interpretation of canine responses, presearch exercise , and diet as mentioned above.…”

“…Sargisson and McLean found that the false alert rate for explosive detection is dependent on positive reinforcement. In addition, physiologic factors appear to affect canine alert such as presearch strenuous exercise and diet .…”