Aw, little Pogo!  That would be a cute name.
I saw a BIG sheltie last weekend.  He was 50#, which is 5# heavier than my dog, and they were the same height.  Even so, they had a different build (she's longer, he was more square) and different heads - Ruby is small, but she doesn't look like a sheltie to anyone who knows what a sheltie ought to look like.

Funny you should mention that. In the late 1950s we had neighbors who bred 
show Shelties and I got to play with the puppies of one litter, to my great 
delight. They offered to sell me one of the pups because it was too big for 
show standards. He was a lot bigger than his siblings.

My parents couldn't afford the $35 price and he went to a pet home 
somewhere, but 60 years later I've not forgotten him. Here's to you, Pogo - 
I hope you had a good life.