I don't really know the answer, Jessica, but I'll be interested to hear what other members have to say. My dog Jack has some arthritis in his left hip where he had surgery. The side effects are scary. And the two vets I've talked to about it say that it should be used when necessary. For example, the instructions are if Jack is having a bad day, give him Rimadyl. If he's having a good day, don't. That sounds so vague to me! I guess for me it's hard to tell if he's "having a bad day" or not. He limps a little when he gets up from a nap almost everyday! Dogs can't tell you if they're having a bad day and they don't complain. How bad of a day is Rimadyl worthy?!