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considered core for dogs. Non-core canine vaccines include those that protect against leptospirosis, canine parainfluenza virus (CPi), Bordetella bronchiseptica
and Borrelia. Canine coronavirus (CCV) vaccine is not recommended as there is little evidence that CCV is a primary enteric pathogen or that the vaccine can protect against such infection. The WSAVA global guidelines do not consider some vaccines that have very restricted geographical availability (e.g. vaccines against canine herpesvirus, Leishmania or Babesia).
WSAVA guidelines provide generic advice to practitioners, but it is impossible to ensure that the guidelines are tailored to best fit the local situation in each of the 86 WSAVA member countries. The VGG encourages national associations to adapt and modify the guidelines for local use where appropriate. This process might involve altering the classification of a vaccine. For example, in the UK, Leptospira vaccine is generally considered core for the dog and attempts are now being made to provide data that define disease prevalence and characterize locally circulating serovars [5].
Core Vaccination of Puppies
The vaccination of puppies is determined by the transfer of maternally-derived antibody (MDA) from the bitch
in colostrum. This antibody is crucial for protection of the pup during early life, but simultaneously blocks the endogenous immune response of the puppy to core vaccination with most available modified live virus (MLV) vaccine products. Canine immunoglobulin has a half
life of around 11 days and there is progressive decline
in MDA concentrations in pups over the first weeks of life. The ‘window of susceptibility’ occurs when there
is no longer sufficient maternal antibody to provide full protection from infectious disease, but where sufficient antibody remains to block the ability of the pup to
make its own immune response to MLV core vaccine. Traditionally, this window has been taken to occur at between 8 – 10 weeks of age, but new evidence shows that higher titre vaccines increase maternal antibody concentrations leading to persistence of MDA for longer periods of time. Studies have now shown that around 1 in every 10 puppies has ‘blocking’ levels of MDA against CPV at 12-14 weeks of age. For this reason, vaccination guidelines now recommend that puppy vaccination (with MLV core vaccines) starts at 8 – 9 weeks of age, with a second vaccine 3 – 4 weeks later and a third vaccine given at 16 weeks of age or older. The puppy protocol now includes a fourth core vaccine, which optimally would be given at 26 weeks of age (and replaces the vaccine that has previously been given either at 12 months of age or 12 months after the anniversary of the 16 week vaccine). This fourth vaccine might conveniently be given at the time of neutering of the puppy. By this schedule, all puppies (except genetically-determined low or non-responders) will be able to mount protective
immunity by 26 weeks of age. A recent study from Australia has shown that the most significant cause of CPV ‘vaccination failure’ in puppies is failure to deliver the final vaccine in the puppy series at 16 weeks or older [6]. Where rabies is endemic, pups should receive 1 dose of vaccine at 12 weeks of age or older, but the VGG suggests that in a high-risk situation (i.e. in an endemic area with known local cases), a second dose of vaccine may be given 2 - 4 weeks later.
The ‘window of susceptibility’ to infectious disease for puppies overlaps with the ideal period to undertake socialization. The WSAVA guidelines endorse strategies to socialize puppies (including ‘puppy parties’), but recommend simple measures to minimize the low risk of transmission of infectious disease at such events.
Core Vaccination of Adult Dogs
For adult dogs, MLV core vaccines should be given no more frequently than every 3 years. For CDV, CAV, CPV there is excellent correlation between the presence
of serum antibody (as detected by virus neutralization test or haemagglutination inhibition test or in-house serological test kits) and protection from challenge with infectious virus. There are extensive data showing that protective antibody persists in adult dogs, even when they have only been vaccinated as puppies up to 14 years previously [7, 8]. More importantly there are data that underpin the legal registration of canine core MLV vaccines for either 3 or 4 years, based on challenge studies that show that vaccinated dogs resist infection for that minimum period after vaccination (the minimum duration of immunity, DOI). Other experimental data show that dogs vaccinated as puppies only are protected from live virus challenge with CDV and CPV at 9 years of age [7]. On this basis, most of the internationally produced canine MLV core vaccines used in the USA, Europe and some other countries now have a licensed minimum DOI of either 3 or 4 years. However, in other countries the identical international vaccines still carry a 1-year licensed DOI, but may still be used less frequently with informed client consent. This is also true for the internationally produced killed adjuvanted rabies vaccines that may legally be given every 3 years rather than annually. Where such products are available with a 3-year licensed DOI, but governmental legislation insists on annual rabies vaccination, it is beholden on the veterinary profession to lobby for changes to the law in order to prevent unnecessary revaccination of adult dogs. For example, in the USA, state laws changed gradually, such that now every US state stipulates triennial revaccination of dogs against rabies.
The currently accepted core revaccination schedule for adult dogs is therefore revaccination every third year with CDV, CAV, CPV and rabies. Where rabies revaccination is still required annually, the schedule might be CDV, CAV and CPV triennially and rabies
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