Detection of catfish off-flavour compounds by trained dogs

Six mixed-breed dogs were trained to detect 2-methylisoborneol and geosmin in laboratory-prepared water. The three dogs most responsive to training were selected for further testing to measure their ability to detect these compounds at levels typical of the early stages of an 'off-flavour' event in catfish pond culture. The dogs were given one out of five choices of off-flavour and 'on-flavour' water samples and were trained to sit at boxes containing off-flavour sample tubes. At the lowest concentration tested, 10 ng L(-1) of the target compound, the mean correct responses for the three dogs were 37%, 43% and 67%. Additional testing was conducted using off-flavour pond water samples containing known amounts of these two compounds that occurred naturally. Correct responses for off-flavour samples varied from 30% to 95%, depending on the sample and the dog. On-flavour samples were correctly identified with 96% accuracy for all dogs and all samples. Dogs may provide practical early detection of off-flavour problems in catfish ponds.