Andre - I saw your picture and appreciate your dogs acheivement, especially if he did not receive any formal training. I have a DD (Deutsch-Drahthaar) which is basically a refined version of the German Wirehaired pointer. The DD's have been bred to a different and higher standard for the last 100 years . You can trace the lineage of your dog back 100 years . All dogs must pass ability tests before they are allowed to breed. One of the tasks that they must perform before they get their utility dog certification is a blood track of 400 meters on a leash. They can then go onto a cold 20 hour track and a cold 40 hour track.
If they have the right temprament and a good nose it is amazing what they can be trained to do.

Best Regards.