2 GPs One Bad/Lame Leg

Question
What would cause this? Both are males(father and son)They are 7-8 years old. Each one only has one bad leg. Just seemed to happen overnight but it gradually progressed. I thought maybe laying down on it so much did it. Neither one has fallen or been dropped so no accidents. I checked scurvy since they have troubles walking but they get plenty of vitamin C. What do you think?

Answer
These are very old pigs by cavy standards. That is a tribute to good care and you are to be commended. I cannot tell you what may be wrong with these boys' legs but since they are father and son it may be a congenital tendency toward arthritis or some other bone issue. At 7 or 8 years of age that wouldn't seem unusual. Being a gradual progression would indicate an arthritic type process. It's not however, caused by lying down a lot.  

Scurvy is a gradual process with other symptoms. It doesn't sound like scurvy, although not every disease behaves like the books say so we can't always say with certainty that it is not.