My Yorkie was awfully smart, too. I also had a Silky terrier female and she was a genius, as well but I don't know if it's in the genes.
A Silky is half Yorkshire and another breed of English terrier.
A Silky is more suitable if you have small children around that could hurt a 4 pound dog.
I have had 100 pound yellow labs, so I've been pulled and have had great experience with the shovel.
The lab is another great dog if you were guarding an area from terrorist attempts.
They are calm, but activate only when it is needed. They are also VERY smart.