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Another topic of controversy surrounding
vaccination is the procedure of annual immunization. Although many
veterinary clinics still recommend annual re-boostering to protect
against disease, some others are now employing a three-year re-booster
schedule . This new
schedule is based on the premise that active immunization to viral
antigens may persist for years or perhaps even throughout the life of
the dog and, therefore, provide long-lasting protection without the need
for revaccination. However, it should be noted that many factors, some
of which are discussed above, such as timing of primary immunization in
regard to maternal antibody levels, efficacy of a particular vaccine to
induce an immune response, use of killed versus modified-live vaccine
and use of polyvalent versus monovalent vaccines, as well as
immune-response of the individual dog at the time of inoculation may
influence outcome effecting long-term protective immunity. Therefore,
some dogs, particularly young adults who may not have developed complete
immunity during their primary immunizations as puppies, may not be
adequately protected against infectious disease if not administered an
annual booster as an adult. To reduce this risk, three-year booster
schedules should be employed only after a dog receives an annual booster
as an adult dog, approximately one year following its primary
immunization series as a puppy.
Special
Added Note on Bacterin-Based Vaccines
Though the general consensus
among specialists in the field is that yearly vaccination against viral
infections associated with canine distemper virus, canine parvovirus and
canine adenovirus are generally unnecessary since active immunity
induced by these vaccines provide at least several years of protection,
this consensus, however, does not apply and should not be generalized to
bacterin vaccines, which immunize against diseases associated with
bacterial organisms. In fact, clinical evidence suggests that bacterin-derived
vaccines including those which protect against Bordetella bronchiseptica
(kennel cough), Leptospira (Leptospirosis), and Borrelia burgdoferi (Lyme
disease) probably don't even provide protective immunity for 12 months
suggesting that more frequent vaccination for these diseases are
required. It is perhaps the common use of combination (all-in-one)
vaccines containing bacterins, which immunize against bacterial
infections such as Leptospirosis and/or kennel cough in addition to
common viral infections, that gave rise to the practice of frequent
vaccine administration. Indeed the incorrect generalization of long-term
immunity, associated with vaccination against viral immunogens, to
bacterin-based vaccines may lead to a decrease in annual vaccination for
bacterial-based diseases and subsequently give rise to a resurgence of
outbreaks of bacterial disease in the coming years. In light of this,
annual re-boostering against bacterial diseases should continue despite
discontinuation of yearly vaccination against viral diseases. For more
information on bacterin vaccines, please refer to the following
articles:
Homeopathic (isopathic)
approaches to immunization have been utilized throughout the centuries
and are currently advocated by some modern-day homeopathic
practitioners and even some veterinarians in dogs who are considered
to be at high-risk for adverse reactions to vaccines. However, a
distinction must be made between those practitioners who advocate
homeopathic alternatives to vaccination in dogs who are at high-risk
of reaction and those practitioners who profess that all dogs should
use homeopathic alternatives in lieu of vaccines: The first recognizes
the importance of vaccines for maintaining the health of our general
dog population while seeking potential alternatives for those in the
population who are not candidates for vaccination; the second is
simply promoting negligence.
“Homeopathic vaccines”
called nosodes are prepared using high, serially agitated dilutions of
infectious agents (i.e. infectious body fluids, vomitus, feces, or
other tissue) which are administered to the animal orally for the
purpose of protecting against later infection with the respective
pathogen. Though some pet owners report efficacy of nosodes for
protecting against infectious disease in their dogs, controlled
clinical studies exploring the ability of nosodes to protect animals
who are directly challenged with infectious disease indicate that
nosodes are not effective for this purpose. In a clinical study by
Larson and colleagues, nosodes administered to dogs completely failed
to protect against death due to parvovirus when these dogs were
administered nosodes of parvovirus-infected tissue over a period of
time and then subsequently challenged with the pathogen. In another
controlled clinical study by W.B. Jonas comparing efficacy of
vaccination to nosode protection against infectious disease, though it
was found that nosodes did increase the survival time following
challenge with infectious disease, efficacy of protection was only 22%
for nosodes compared to 100% protection with vaccination; that is,
about 4 out of every 5 animals administered nosodes died from the
infectious disease when challenged. This 22% efficacy is, in fact, the
highest reported efficacy for nosode protection in any controlled
clinical study to date.
In light of the data
showing inefficacy of nosodes for protecting against infectious
disease, why are some practitioners still promoting nosode use?
Proponents of nosode-use such as Jean Dodds, DVM and others in the
field do not promote the use of nosodes in lieu of vaccination of dogs
in general; they promote the use of vaccine alternatives like nosodes
in dogs that have a suspected predisposition (certain bloodlines with
genetic risk) or underlying health conditions (as those discussed
above) that put these particular dogs at higher risk for developing
adverse reactions to vaccines. As will be discussed in the next
section, although nosodes do not provide the assurance of protection
that vaccines do, nosodes may provide some benefits over not
vaccinating these dogs at all. The wide-spread notion, however, of
totally replacing vaccination with the homeopathic alternative of
nosodes is purported rather by some in the field of alternative
medicine who continually use the reports of Dr. Dodds and others out
of the context in which they were initially written.
Are nosodes a viable
alternative for protection against infectious disease in dogs that
cannot be vaccinated due to health complications? Vaccination
remains the single most effective method for protecting against
infectious disease in healthy animals. In those dogs with higher risk
for developing vaccine-associated complications, alternatives such as
nosodes will not provide effective protection against infectious
disease if the dog is exposed to a moderate- or high-dose of
infectious pathogen sufficient enough to bring about active disease or
in cases of infectious disease outbreak. If one considers low-dose
exposure to a pathogen, however, it is conceivable that nosodes could
possibly provide some protection in regard to reducing severity of the
disease. Ironically, however, this nosode protection would only be
most effective in the presence of a widely vaccinated population.
The current wide-spread use
of vaccination in the dog population creates a condition known as
“herd-immunity”. Herd-immunity occurs when vaccination of large
numbers of individuals within a population decreases the occurrence of
infectious disease within a population and thus actually protects
those few in the population that may not be vaccinated from being
exposed to and acquiring infectious disease. Though many vaccines do
not prevent a carrier state (that is, a vaccinated dog that may be
exposed to an infectious pathogen will be protected from disease but
may still shed the pathogen in the environment), vaccination typically
reduces the amount of pathogen and the duration of time that the
pathogen is shed into the environment and thus decreases likelihood of
exposure to and contamination of other dogs. Therefore, herd immunity
alone does not assure freedom of risk from disease. In light of the
Jonas’ finding that nosode treatment did provide some protection,
albeit minimal, to treated animals as evidenced by longer survival
times prior to succumbing to infection, administration of nosodes to
dogs with high-risk for vaccine reactions may provide some marginal
benefit in reducing risk of infectious disease but only in a
population protected by herd-immunity and only if these nosode-protected
dogs were to receive very low exposure to a pathogen. More controlled,
clinical studies, and not anecdotal reports, in this area are clearly
needed, however, before one can make any assumptions on the
reliability of nosodes to effectively protect against low-grade
infections. As more dog owners, however, turn to using nosodes in lieu
of vaccinations based upon the unsubstantiated claims that vaccines
are dangerous to all dogs in general, herd-immunity will decline and
with it any hopes of using nosodes as a vaccine-alternative in dogs
that are verifiably at higher-risk for vaccine side-effects.
Finally, in absence of
controlled clinical studies to evaluate nosode protection in the face
of low-grade infection and the improbability of assuring that an
individual dog is only exposed to low levels of a particular pathogen,
to date the safest alternative for reducing risk of secondary vaccine
side-effects while also providing effective protection is the use of
alternate types of vaccines (i.e. killed-vaccines, sub-unit vaccines
or mono-valent vaccines) rather than multivalent vaccines in dogs with
an underlying health condition, as those discussed above, or with a
suspected predisposition to vaccine side-effects. For example, recent
clinical studies have demonstrated that using vaccines with a lower
valency (i.e. monovalent, tri-valent) significantly reduces adverse
side-effects that frequently occur with multivalent vaccines while
still providing effective protection against infectious disease.
For a list of URLs providing
more information on vaccines and the canine immune system visit the
"Vaccination Issues" page
of the Canine Epilepsy Resources Homepage.
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