I have decided that i would like to start to administer my pets(dog,horse and 2 cats) vaccinations myself, but I have notice that there are several brands of vaccines for the same diseases. Would there be any issues if I switched brands and went to a vaccine that covers sevearal diseases or vice-versa? If I did this would I have to administer the vaccine twice and then contine annully or would I give it as an annul booster as if there where no change? Thank You.