Training von Hunden für Suchaufgaben am Beispiel von Staphylococcus aureus als Mastitiserreger der Milchkuh

"Training sniffer dogs to detect Staphylococcus aureus in mastitis-milk"

Dogs and their ability to perceive smells even in extremely weak concentrations offer us many possibilities, even in diagnostic areas in medicine.
In this study, using Staphylococcus aureus as a mastitis pathogen in dairy cows, we tested whether it is possible to develop a training protocol for dogs, to recognize and indicate this bacterium in milk.
The training protocol, developed in this study, can serve as a guide to train dogs to differentiate odor of bacteria and is meant as a basis for further development and improvement.
Ten dog handlers took part in this study with their private dogs. It was carried out in 4 experiments.
The dogs were initially trained to indicate Staphylococci grown on agar plates. In the test, 8 dogs examined 100 samples each, 10 of which contained odor of Staphylococcus aureus. Four dogs correctly displayed all positive samples and achieved a sensitivity and specificity of 100%. On average of all dogs the sensitivity was 91,3 % and the specificity 97,9 %.
In the second experiment, the dogs were asked to recognize Staphylococcus aureus in milk. In this experiment, the dogs had difficulty identifying the target smell. We speculate that the concentration of the bacteria for training was probably too low. Only 2 out of 6 dogs completed all 10 trials. The sensitivity was 55 % and the specificity 95 %. For all dogs the sensitivity was 33,3 % and specificity 92,4 %.
The training protocol for experiment 3 was then adapted and intermediate steps were incorporated in which the dogs were slowly accustomed to lower bacterial concentrations. In the next test, each dog searched a total of 105 samples with odorants in 15 rounds of 7 samples each. The dogs achieved an average sensitivity of 83,3 % and a specificity of 97,9 %.
The last experiment tested whether dogs trained in this way are able to recognize Staphylococcus aureus in milk that comes from dairy cows suffering from mastitis. 5 out of 6 dogs successfully passed the test. The dogs achieved an average sensitivity of 60 % and a specificity of 92,8 %. One dog recognized 8 of 9 out of 70 samples with the target smell and had a sensitivity of 88,9 % and specificity of 95,1 %.
Dog training for odor differentiation of bacteria is possible. With the developed training protocol, not all dogs were able to complete the task in the given time. There are many individual differences that should be discussed in more detail in the training protocol. It became obvious that small training steps are important for achieving the training objective. The change in concentration of the target odor must also be considered as an important training step.
This is the first work to show that dogs can recognize and indicate Staphylococcus aureus in milk from dairy cows with mastitis. A training protocol was created, with which 75 % of the dogs reached the training goal and which can serve as the basis for training dogs to distinguish other types of bacteria.