A dog's size and weight can be deceptive. They have a very high lean body mass compared to humans.
My little boy Yorkies averages about 8.5 lbs. When I pick him up he feels like one of my 20 lb. barbell weights!
Nice photos! I give your wife big kudos for her love of dogs. There can never be too much love man's best friend!
Ask her if she would be interested in learning about some fascinating research about her new family member?