Ladymom gave you some great info above. I'd recommend you get a 2nd and even possibly a 3rd opinion, depending on what the 2nd says. There can be differences in grading btwn vets and you should really get an opinion from an Orthopedic Surgeon (although, he also has a vested interest in a higher grade - bc it means surgery dollars). There are grade 1/2s that may never need surgery.
In the meantime, you should purchase Cosequin and get your dog on it immediately for joint health - it can help greatly.
