Hi,
My Max is just 3 lbs, an My Bobo is 3 1/2 pds. So far I have had nothing wrong with them. Max is almost a year old Dec 5th, an Bobo is 2. They play all time and are really great buddies.
You just have to be careful where you step an going thru doors. Also I make sure they have their sweaters on when I take them out to potty. They seem to get cold easily.
Max & Bobo & Libby says Hi!
Here is a picture of my two furbabies

.
P.s. We say all they are.. chicken bones & lint! hahaa