The quick answer is, “way more than you think.” The comprehensive answer is it’s complicated. That’s because researchers have learnt that it depends on a lot of things, from training and their owner/trainer’s intelligence to their breed, occupation i.e. herding, rescue etc., and how you speak to them.
Currently, the record-holder for the most known words is a border collie named Chaser, who lives in South Carolina, and knows 1,022 words. However, Chaser’s owner spent a massive amount of time teaching her different names for items as well as different actions. Chaser has even shown the ability to join verbs and nouns together to perform specific tasks. Chaser can use the process of elimination to select toys that she hadn’t been taught the name of – for example, she didn’t recognise “Uncle Fuzzy”, therefore he must be connected to the item she didn’t know the name of – Amazing
No question Chaser is an extraordinary example, but what about your much loved dog? Researchers tell us that most dogs have a vocabulary roughly equalling that of a 3 -year-old, with the “average” dog understanding about 165 different words and phrases.
The super-smart class understand about 250 different words, and they’re mostly working and herding dogs. Which isn’t entirely surprising, given that their owners need to be able to count on these dogs to understand what they’re being told so they can carry out specific tasks.
While research demonstrate that herding dogs come out on top, dogs like terriers and hounds recognise considerably fewer words. That might have something to do with their original purpose, which was to simply chase whereas herding dogs need to be able to follow commands and make snap decisions on their own, which has translated to smarter dogs today.
Of course, I new Zeus (my German shepherd) and Misha (my Briard) were geniuses they’ve been bred as herding dogs, not that these two spoilt pooches heard anything for a living, except us into doing exactly what they want !!!