Unfortunately the PZI Vet has been discontinued and supplies of it are next to impossible to come by at this point. I think someone posted a phone number recently where you could call the company and i think they could tell you if there was any out there somewhere.
if not, you can switch over to it's replacement, ProZinc. From what I've seen it looks like you can make the switch right over with no worries as the ProZinc is supposed to be working the same as PZI Vet did.