Angel to Abandoned Puppies
Join Date: Sep 2002
Location: Arizona now
Well, I'd say it could be multiple things. My first thought was that he has had a growth spurt. It is pretty typical for large breeds, not sure on the small though, for them to have a growth spurt that causes them to "outgrow" the protective coating on their bones. This tends to cause temporary lameness in the leg. From what i've seen it will last a few weeks, and generally goes from one limb to another.
It could also be arthritis, but that seems unlikely at his age. Anything is possible. It could also be hip/elbow displacia problem. My best suggestion would be to have your vet xray the limb to get the best determination.
In the meantime if it is really painful for him you could give him some baby asprin (not tylenol.. asprin) to help ease the pain.
We'll be thinking of your baby. And welcome to PT