A dog who plays with invisible pet toys may be suffering from an obsessive disorder that could require reward-based training to break, an expert has said.
A Daily Telegraph reader contacted the paper's vet columnist about their dog, who has started staring at invisible objects, barking at them and pouncing on them.
The reader thought that the dog could be seeing the ghost of a rodent or something else invisible to the human eye.
Dr Wedderburn wrote: "It sounds as if your dog has some sort of obsessive disorder that you’ll need professional attention to get sorted.
"You may also need to start doing plenty of reward-based training, so that he responds to your commands reliably rather than being distracted by illusions."
The vet added that pet medication can sometimes help to break this sort of habit. A vet can also refer the owner to a good pet behavioural specialist or the Association of Pet Behaviour Counsellors.