A vet prescription is required for the medicine you have chosen. Katalax is a palatable blend of white soft paraffin, cod liver oil & malt extract that aids in the elimination of hairballs.. If you do not yet have a prescription then you can print out the following blank veterinary Prescription Form which you can ask your vet to fill in when you next visit. Please note that changes to legislation in 2005 means that Vets must offer you a prescription to take away & not just supply you the medicines directly. This is to ensure more competition & lower prices for you.