Most dog-owners flush with pride if their canines perform a trick for a treat, but Chaser the border collie has learned over 1000 words for his toys. Don't believe me? There's video below.
Two psychologists introduced the dog Chaser to a new toy, repeating its name over and over again. When the pile of plush amounted to 1022 objects, they found she could fetch individual toys when requested, with groups of 20 toys being fetched 838 times over three years, with at least 18/20 correct toys chosen every time.
Lucky for Chaser, she's owned by a psychologist, Dr John Pilley, so can repeat these tests well into the night. His psychologist friend Dr Reid said "we worked with Chaser for four to five hours each day testing her on the words over and over again and were able to establish that she could remember and distinguish between them all. We're not saying this means dogs can learn language in the same way children do, but it does show they are capable of learning many more words than might have been thought." [New Scientist]