My dogs have developed rashes and hair loss...help?

I agree with the others. First step would be to get them to the vet could be something on the garage floor maybe some sort of chemical. Second step would be to stop feeding them purina. It is ful of crappy ingredients that dogs can't even digest and chemical preservatives. It may cost more for other foods but in the long run you pet will live a much longer healthier life and you will save on vet bills as a result. Trust me, its worth it. There are plenty of other questions on here talking about good foods. As a general rule don't fee3d your dog any type of food you can buy at the grocery store or walmart including the treats they sell there.