I believe that smart animals can amass of vocabulary of a certain amount of words.

I had a dog that could apparently count to three. When he was a pup, I would get him toys, of course. He esp. loved his hard bones.

And he liked to keep them all with him. So at first, when he had one bone, it came with him whenever we changed rooms. Later, he would have to go back and get the second bone. Then, he had three bones. But sometimes, I would see him get confused as he was returning for the third bone, as if he couldn't remember whether he needed to go get another one or not. Eventually, he stopped taking all his bones with him everywhere.

Yes, dogs are great, GreyGoose. And I'm sure other pets, too. Don't geese have a reputation of mating for life?