Hi................Your little Doobie definitely looks all yorkie to me. Because of different breeding practices and because of the lines they come from, even though the yorkie standard says one thing, they do come in all shapes, sizes, and colors. Doobie is adorable, looks like he's got a silky coat and at just 5 1/2 lbs at 8 months, I'd bet he will stay in or close to the yorkie standard in size (4-7 lbs). He looks to have long legs; is he tall? Maybe it's just the pictures. In any case, I've yet to own a "perfect" yorkie.........if there are any, but as long as our babies are perfect in our eyes, that's all that really matters.
Doobie looks and sounds wonderful! Enjoy him!
