Effect of odorant pre-exposure on domestic dogs' sensitivity on an odorant detection task

Although dogs are widely trained and deployed for odor detection work, relatively little research has investigated procedures that may more efficiently train or increase detection performance. Prior research in rodents and humans suggests that odorant exposure may enhance sensitivity to that odorant; however, other research has suggested that exposure may have the opposite effect. Our aim was to assess whether exposure to odorants influences dogs' sensitivity to those odorants on a subsequent operant task. We specifically tested whether simply being non-contingently exposed to an odorant or being exposed to an odorant in an appetitive Pavlovian conditioning paradigm influenced dogs' sensitivity to that odorant. In a pre- post-test design we assessed changes in dogs' sensitivity to two odorants. In the first phase, dogs' sensitivity to both odorants was assessed using a descending series of half (binary) dilutions presented using a liquid-dilution olfactometer. Then half the dogs were non-contingently exposed or Pavlovian conditioned to one odorant while the second odorant remained an unexposed control. Sensitivity to both odorants was then re-assessed using the same procedures as during baseline. Dogs showed a significant increase in sensitivity to the Pavlovian conditioned odorant compared to both the control odorant (p < 0.01) and compared to the non-contingently exposed odorant (p < 0.01). These results suggest that Pavlovian conditioning may be a simple procedure to enhance olfactory sensitivity to a target odorant.