Authors: Lydia Burnett1, Nick Hebdon2, Pete Stevens3, Monica Moljo1, Lauryn DeGreeff1, Lindsay Waldrop2

1 Florida International University, Global Forensic and Justice Center and Department of Chemistry, Miami, FL, USA; 2Chapman University, Schmid College of Science and Technology, Biological Sciences, Orange, CA, USA; 3The Scentsable K9, San Diego, CA, USA

Canines are well-known and often utilized in forensic science for their extensive scent detection capabilities. They are often considered the “gold standard” field detection method for a variety of materials, including biological substances, illicit drugs, and explosives. Despite their prevalence in the field, relatively little is known about how canines transport volatile organic compounds through their olfactory system. In this study, canines of a variety of breeds were presented with 2-ethyl-1-hexanol and ammonia, which have different diffusion coefficients and vapor pressures. The sniff frequency, volume, and flow rate was measured in response to each compound. These metrics were measured when the canines first encountered the odor, after one week of training, and after the canines were fully trained on each odor. The canines sniffed 2-ethyl-1-hexanol more frequently than ammonia. Small dogs (<30 pounds) took in less volume and had a lower maximum flow rate when sniffing than large dogs. Sniff frequency, volume, and flow rate are similar when interacting with both 2-ethyl-1-hexanol and ammonia, indicating that canines may not adjust sniffing behavior in response to varied chemical properties. Uncovering the mechanisms by which canines interact with different odor properties could lead to more effective training methods and inform designs for artificial sniffing devices.