Don't know about younger dogs but the vet I go to advises AGAINST giving boosters to older dogs as it can be too much for their system, he's seen a number of oldies sicken (and one greyhound with a weak heart died) after having being given annual boosters. My dads old border collie only ever had the pup vaccines and she lived till she was 18, my terrier has only had the pup course and she's ten in september and still full of life, my lurcher is a year now and he won't be having any boosters either, and my vet never suggests that dogs be given boosters, he's a good old boy and a countryside blo