I consider Happy, Misty, Electra and Blair to be medium (21", 18", 17", 15")

I consider Rusty, Ripley and Perky to be small(15", 13", 11")

I should probably explain why I have 2 15" dogs classified in differnt catagorys lol while Rusty and Blair are the same height, Rusty is smaller, she is very fine bones and appears smaller then Ripley, he is only 15lbs so I consider him to be small. Blair however has a bigger build and looks more like Electra in height, he is 22lbs so I consider him medium.