Allivet has saved me money over the past few years, though Chewy is getting on board with their new prescription products. The problem with Allivet is that I've paid for expedited shipping several times and always regretted it because the packages still arrive in 5 to 10 days. This includes second day. I've also had them accept an order then not be able to fill it for a considerable time. That was a while ago, but they always take longer than Chewy or 1-800-petmeds.