http://www.msnbc.msn.com/id/31833642/ns/health-pet_health/ Many pet supplements don’t meet claims Tests show some skimp on ingredients, contain lead or not proven effective Arthritis supplements bought by millions of pet owners for their dogs, cats and horses sometimes skimp on the ingredients the makers claim can help aching paws and aging joints, and some contain high amounts of lead, an independent laboratory found. Four of the six joint supplements for animals tested by ConsumerLab.com lacke