APOPO has a breeding program which supplies rats ‘as needed’ for the training, research and detection programs currently underway. We have breeding couples and successfully trained rats that are taking a ‘work holiday’ also participate in our breeding program. Sometimes additional wild rats are introduced into the breeding program (to scale up productivity). In the early days we attempted to use wild-caught rats, but it became clear very quickly that it was not going to work. The rats were aggressive and just could not be handled. Now we breed the rats and begin handling them and exposing them to all kinds of objects, sounds, and smells as soon as they open their eyes, at about four weeks of age. When the rats are raised in constant contact with people, they are very easy to handle and train.