I understand how general of a ? it is, but do you have a certain brand you like to use? Meaning that you won't use any thing but that brand, such as Novartis, Boehringer,Pfister,etc. Do you ever mix them from year to year? Use one brand for the initial vaccination, come back in 2 to 3 weeks later with another brand for the booster round, then annually with another brand. I ask only because most of them seem to say the same thing on the directions, and if there for the same diseases would it hurt to use a different brand. It often seems that when I go to get my medicines the coop, or farm supply doesn't carry that brand of vaccine/ medicine any more they have something different but the tell you its the same thing, is it?