Assessing the Impact of Fecal Volume on Detection Dog Responses to Chronic Wasting Disease Training Aids

Chronic wasting disease (CWD) is a fatal prion disease in cervids. Because prions persist in the environment, early detection is essential for containment. Trained detection dogs have shown promise as a noninvasive surveillance method through identification of volatile organic compounds associated with CWD in white-tailed deer (WTD; Odocoileus virginianus) fecal matter. To reduce the risk of environmental contamination, recent CWD detection work has used cotton training aids incubated (i.e., passively odor exposed without direct contact) with small quantities of WTD fecal matter. However, operational detection scenarios often involve exposure to much larger volumes of fecal matter, requiring detection dogs to generalize from their training aid odor to the real-world target odor. This study examined whether detection dogs trained on cotton aids incubated for 24 h with 1-2 g of fecal matter (small quantity) could generalize to aids incubated for 24 h with 22 g of fecal matter (large quantity). Four detection dogs completed two tests: the first test measured their initial responses to the large-quantity aids and the second test was conducted after three training sessions in which they were positively reinforced for alerting to the large-quantity aids. Dogs did not significantly differentiate between CWD-positive and CWD-negative samples in the first large-quantity test, but showed significant improvement after training; as such, generalization did not occur spontaneously from training only on small-quantity aids, but a brief training exposure to the larger-quantity aids enabled better performance. This study emphasizes the importance of considering odor variability between training scenarios and the operational scenario. Results provide information relevant to improving operational field performance. Future work should explore training paradigms that increase flexibility in odor recognition across different contexts.