Solution: This and chasing of reflections from shiny objects are surprisingly common problems in the dog population. Very often the condition starts quite innocently by the use of a torch or more often a laser pointer. The behaviour becomes entrenched, unfortunately because the owners usually laugh at the dog's antics.

Regrettably, this tends to reinforce the goings on and the dog-becomes even more intent on its efforts to catch whatever is the 'shadow'. It is a prey behaviour carried to the extreme, that eventually becomes uncontrollable. It's an obsessive, compulsive condition that's 100 times worse than nail biting.

Stopping it requires a tactic that immediately stops the behaviour and then provides the dog with an alternative. In this case we banged two saucepan lids together to stop the chasing, then asked the dog to sit and rewarded this behaviour, before playing a game. Unfortunately, heavily entrenched behaviours like this often require medication as well.