Also, I see that she is part Beagle. Is her weight an issue?

Older dogs need to be kept leaner than most people think. Excess weight hurts. My pekingese has luxating patellas but I keep him very trim, active, and he gets a lot of natural supplementation: i.e. salmon flesh/fat, chicken/beef/turkey/pork cartilage, shellfish shells, etc. He's very active and pain-free for an almost 10 year old!

Store bought supplements are good, but I'm cheap and feel more comfortable going about it the 'natural' way Plus, I'm awful about remembering medications! Walmart and Costco are most cost-efficient, I believe...