MARK WHITEHOSUE SAYS: Unfortunately your gun dog has been given the opportunity to handle warm /live game before becoming proficient in all aspects of retrieving cold game first.
You must take a few steps back and train him to release on a specific command. The command that I use is ‘dead’.
To prevent unnecessary suffering to any animal or bird when being gripped firmly in the mouth, this release should be swift.
Practice with as much cold game as you have access to on a daily basis and use the new release command on every retrieve.
Ensure that you only give this command once you have taken hold of the retrieve with both hands.
Any delays in relaxing his grip on the retrieve once you have given him the command must be dealt with firmly by placing your foot on his paw and applying some pressure, repeat the command ‘dead’, and keep gently increasing the pressure until he releases the game.
Give your gun dog plenty of vocal praise on releasing the game.
He will soon associate the command ‘dead’ with some discomfort but equally he will associate the quick release with praise and pleasure.