[SWHouston]

I'm having a little trouble understanding just how this works.

My Vet tells me that "he" has to have a history of 3 years of continuous inoculations, before he can "issue" the 3 year tag.

The way it seems is that, is there some sort of resistance built up, where if less than 3 years, the Dog is vulnerable. And after that, it's ok for a 3 year run without any inoculation.
Is that right ?

What I don't understand is...
Why does it take so long, and...
Why does it have to be with the same Vet ?
Is there a difference {stronger meds) in the 3 year, than the standard 1 year ?

I trust my Vet, but...
This smells fishy. I think it's just a gimmick to get someone to stick with the same Vet for a longer period.
(not that I have any reason to change...at this time)