Trained dogs can accurately discriminate between scents of saliva samples from dogs with cancer versus healthy controls.

Objective: To determine whether dogs can be trained to utilize olfaction to differentiate between saliva samples from dogs with cancer and those from healthy control dogs.

Sample: Canine patient saliva samples were collected (October 2020 to July 2022) from 139 dogs diagnosed with malignant tumors and from 161 healthy dogs (control samples) for use during training and testing of the dog detection team. Samples from canine patients were collected prior to treatment with radiation therapy or chemotherapy.

Procedures: Six pet dogs (mean ± SD age, 5.4 ± 1.9 years) were trained for odor discrimination between healthy control and malignant tumor samples. Training of the dogs, using a reward-based positive reinforcement method, took place 1 to 3 times per week for a period of 6 months (January to June 2022). After training was complete, a subset of samples not utilized during the training sessions were selected for use during odor discrimination testing of the dog team.

Results: The trained dogs could accurately distinguish between samples from cancer patients versus control dogs with a mean sensitivity of 90% and mean specificity of 98%, and with mean positive and negative predictive values of 95%.

Clinical Relevance: This study serves as preliminary evidence that dogs can be trained to detect differences in scent between saliva samples from cancer and normal patients. Further studies should expand upon these results with a larger sample, varied tumor types, use of non-cancer diseases as controls, and exploration of this technique in feline patients.