I have a two year old Chihuahua named Rocky.Hes a full blooded Chihuahua and a tall breed, but he's really skinny and unhealthy looking.Plus with a name like Rocky I kinda wanted to make him a little more muscular and healthy looking.Any suggestions
Chihuahua's aren't meant to be muscular.
Walk him, play fetch with him.
And the rest is genetics. If you wanted a "Rocky" you should have bought a bigger muscular dog.