A seven-year-old dog in Austria called Betsy has amazed scientists by being able to recognise more than 340 words.
Most dogs can recognise about 15 commands.
Betsy's skills were recorded as part of the BBC's science programme Horizon.
It examined the increase in scientific investigations into canines, their unique relationships with people, and how they are helping to identify the causes of some human diseases.
Horizon: The Secret Life of The Dog is broadcast on Wednesday, 6 January at 2100 GMT and can be seen afterwards at the