So, I'm doing my first vaccine myself (eek!) for the pup and I've been looking at vaccines (and wow, I'm suprised at how cheap that are!) and comparing what I'm getting with what Blaze's little 'puppy pack' that he got from the vet says. Blaze got two Lepto vaccines, one at 12 weeks, and another at 15 weeks. But I'm reading where most vets say DON'T give a Lopto vaccine to young puppies. Whats the deal?