2013 World Small Animal Veterinary Association VACCINATION GUIDELINES FOR NEW PUPPY OWNERS http://www.wsava.org/sites/default/files/New%20Puppy%20Owner%20Vaccination%20Guidelines%20May%202013.pdf
" 2. The WSAVA also states that the last puppy vaccine against the core diseases should be given at 14-16 weeks of age. This is because, before this time, the mother passes immunity to her puppies, and this ?maternal immunity? can prevent the vaccine from working.
3. A high percentage (98%) of core puppy vaccines given between 14-16 weeks of age will provide immunity against parvovirus, distemper and adenovirus for many years, and probably for the life of the animal .
6. The WSAVA supports the use of titre testing. …."