Funny Dog

Dr. Coren has also argued that dogs demonstrate a sophisticated theory of mind by engaging in deception, which he supports with a number of anecdotes, including one example where a dog hid a stolen treat by sitting on it until the rightful owner of the treat left the room. Although this could have been accidental, Coren suggests that the thief understood that the treat's owner would be unable to find the treat if it were out of view. Together, the empirical data and anecdotal evidence points to dogs possessing at least a limited form of theory of mind.
A study found a third of dogs suffered from anxiety when separated from others.
A Border Collie named Chaser has learned the names for 1,022 toys after three years of training. It is more than Rico done before and also so many that her human handlers had to write on them in marker so that they wouldn't forget.