In recent years, vaccination protocols have undergone a number of changes, such as which vaccines to give, when, and how often.
A significant improvement has been the classification of vaccines into categories of core, noncore, and not recommended. While
not everyone agrees with which vaccine products belong in which category, there is a general consensus that we can no longer
vaccinate every animal with every available vaccine every year. There are far too many individual products, types, and brands
to attempt to use them all. Instead, practitioners must choose which vaccines are necessary, which are optional, and which
are never used in their clinics. The following guidelines are based on the 2006 AAHA Canine Vaccine Guidelines, which were
published in JAAHA and available on the Internet.
Certain vaccines are recommended for every dog, regardless of region, lifestyle, or other factors. The diseases are not easily
treated and are often fatal. Therefore, all dogs should receive these core vaccines as a puppy series (primary immunization)
and continued as adults.
Widespread vaccination has reduced the incidence of canine distemper to the point where younger practitioners may never have
seen a case. However, the virus is still a danger and outbreaks are reported in shelters and in areas where vaccination of
the population is inadequate. Two types of distemper vaccine are currently available: modified live virus (MLV) and recombinant
(canarypox). Either type can be administered to puppies and adult dogs.
Vaccination should begin at weaning (6-8 weeks of age) and continued every 3 weeks until puppies are 16 weeks of age. Maternal
antibody interference can prevent good immune responses to vaccination, so repeated vaccination is necessary. One study suggested
that recombinant distemper vaccine overcomes this interference and may be more effective than MLV when rapid immunity is needed,
such as during an outbreak.
Practitioners may choose to vaccinate most dogs with most or all of the vaccines available, with the belief that prevention
is better than treating the disease. In the 1960s through the early 1980s, this practice was common and quite easy, as the
only vaccines available were DHLPP and rabies. Today there are far more vaccine products, new antigens, different combinations,
and even different disease patterns than in the past. It is now virtually impossible to vaccinate every dog with every available
product. To address this increase in number and complexities of vaccines, the Guidelines categorize them as core, noncore,
and not recommended. As the names imply, vaccines that all dogs should receive are core, while noncore are optional based
on lifestyle, local disease prevalence, and risk/benefit ratios. The third category of "not recommended" has proven to be
controversial, as some vaccines that practitioners use commonly and believe are helpful (and actively marketed by vaccine
companies) are now discouraged.
Duration of immunity
Another controversial approach in both the 2003 and 2006 Guidelines is to administer core vaccines every 3 years instead of
annually. Veterinarians have questioned both the legality and wisdom of delaying boosters for 3 years when vaccine labels
clearly state that annual revaccination is recommended. Discussions of "off-label" use and whether practitioners will be held
responsible if something goes wrong are common. There was and is a feeling that annual vaccinations have nearly wiped out
common infectious diseases and any change would be a regression, possibly leading to outbreaks. The potential loss in practice
income if annual vaccinations were discontinued has been a major concern. The question is asked "Why every 3 years instead
of every 2, or 4, or some other interval?" And perhaps the underlying issue is "if it ain't broke, why fix it?".
Research undertaken by several vaccine manufacturers and independent investigators since the 2003 Guidelines were published
have demonstrated that core antigens do indeed protect dogs from challenge 3 years after vaccination. Many practitioners were
reluctant to consider 3-year intervals because no challenge studies had been published. Now we not only have peer-reviewed
research to back up 3-year duration of immunity (DOI) but also a USDA-licensed vaccine.