I believe they understand time from an animal's point of view, not a human's (which seems silly to even say). All animals do, so that is crazy to say they don't. They definetly don't need a watch to tell me when it is time for them to eat. Sampson gets down right bossy if his food isn't in his bowl at a certain time every day. They expect certain things at certain times of the day. Of course they aren't going to know when their birthday is or be able to differentiate between 2 and 3 years, but they definetly understand time.