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Vaccination questions and answers
Introduction
Immunizing dogs against disease seems to be
a simple process; pet owners may even take vaccinations for granted. It is both
the most routine procedure performed in veterinary clinics and also the one most
prone to confusion and misconception. This article attempts to answer some
common questions dog owners have about vaccinations.
How does a vaccination work?
In simplest terms, a vaccination stimulates
the dog's immune system to protect itself against disease. When the antigen or
infectious agent enters the dog's body, it is recognized as foreign and
antibodies are produced to bind to it and destroy it. Even though the invader is
gone, the cells that manufactured the antibodies "remember" it and
will respond more quickly the next time the same agent is confronted.
Don't dogs get sick from a
vaccination?
When vaccines were first being
investigated, patients were actually given a less severe form of the disease or
a related disease, with the idea that it was better to be a little bit sick now
rather than a lot sicker later. Giving people cowpox to prevent smallpox was an
early form of vaccination. Today's vaccines are attenuated (weakened), killed,
or only pieces of the virus and don't actually transmit the disease.
What about vaccine reactions?
It is true that some animals have a
systemic reaction, including a low-grade fever or muscle aches and pain. This
reaction is more common in young and toy breed dogs and causes them to eat less
and sleep more for 24-48 hours. Rarely, dogs will have a more severe reaction,
characterized by hives, swelling of the face, or even vomiting. This reaction is
easily prevented by giving antihistamine at the time of subsequent vaccinations.
Leptospirosis, the component most likely to produce such strong reactions, can
be left out of some vaccines. If your dog has had a vaccine reaction in the
past, don't skip future vaccinations but do warn the veterinarian so he can take
steps to prevent a recurrence.
Which is better, killed virus vaccines
or modified-live types?
Each type of vaccine has strengths and
weaknesses. Modified-live vaccines provide stronger, longer-lasting, and more
rapid protection, including local immunity. They are less expensive and may
require only one dose to be effective. They have a potential to become active
and cause disease, especially in a patient with a weakened immune system; to
create immunosuppression, or to cause abortions in pregnant dogs. Careful
handling and storage are required to prevent breakdown of the active
ingredients.
Killed vaccines cannot become virulent and
are less likely to be immunosuppressive or cause abortions. They remain stable
during storage. They are more likely to cause allergic reactions, require more
initial injections and more frequent booster shots, and do not produce local
immunity.
A good example of the differences between
modified-live and killed vaccines is the use of Bordatella vaccinations for
kennel cough. Killed vaccines require two injections but are only 60- 80 percent
effective against disease and don't provide local immunity at the level of the
airway. Modified- live vaccines are given intranasally, require only one dose,
and start providing local immunity within 48 hours.
Can you overload a puppy with too many
things at once?
Probably not. Some researchers blame the
rise of immunemediated disease on frequent vaccinations with large numbers of
modified-live viruses. They feel this over stimulates the immune system, causing
it to recognize everything as foreign and leading to tissue rejection.
Currently, this theory is not accepted by most veterinary practitioners. Those
who do adhere to this theory advise giving separate vaccination every few days
instead of using combination vaccinations.
What this approach fails to consider is the
interference caused by too-frequent administration of vaccines. Because the
first shot will create a blocking effect and not allow the body to respond to a
second or third shot a few days later, it is better to administer several
antigens together than to divide the vaccines into many injections.
It sounds like vaccinations are
dangerous. Is it worth the risk?
Absolutely! The risks associated with
vaccines are slight compared with the risk of contracting a fatal disease like
distemper, rabies, or parvovirus.
Shouldn't vaccines contain the most
things possible?
No. Some people feel they receive a better
value for their money if a vaccine contains six or seven or more antigens
instead of the five-in-one combination most often used. Vaccination schedules
based on your dog's age, breed, and lifestyle as well as your geographic
location and your veterinarian's advice are more effective than trying to
squeeze the most antigens into a one cc injection.
My dog was vaccinated against (parvo,
kennel cough, etc) and got it anyway. Why?
Vaccine breaks occur for many reasons.
Fever, steroids, disease, and maternal antibodies will block the patient's
ability to make antibodies. Improper storage and handling of the vaccines or
incorrect administration will also lead to vaccine failure. If given too close
together, vaccines can be blocked by earlier shots; given too far apart, the
memory response of the immune system is not properly stimulated.
Vaccines given to very young puppies (under
six weeks of age) or to sick or immunocompromised patients may be ineffective.
In the case of parvovirus, it has been demonstrated that Dobermans and
Rottweilers are more susceptible to infection. Some veterinarians recommend
extra vaccinations for these dogs or for dogs who are often in contact with
other dogs.
How many shots does a dog or puppy
need?
There is no one answer for this question,
but a few basic rules apply. A minimum of two multivalent vaccinations
(including distemper and parvo) given three to four weeks apart are required for
every dog or puppy over three months old. An additional vaccination against
rabies is also necessary. Vaccinations against coronavirus, Bordatella, or Lyme
disease are based on owner's needs and veterinarian's advice.
For young puppies, vaccinations usually
start at six-to-eight weeks of age and are given every three-to-four weeks until
the puppy is 16 weeks of age. Recent information regarding parvovirus may extend
this recommendation to 18 or even 20 weeks, especially for Dobes and
Rottweilers.
Part 2
So why vaccinate?
Although there is a growing concern over
vaccine frequency, there is no doubt that vaccines control diseases that can
kill puppies and dogs and protect individual dogs from illness and death.
According to an article in the Journal of
the American Veterinary Medical Association in 1995, concerns center on the
potential for vaccines to trigger autoimmune diseases in susceptible dogs and
the necessity for annual boosters. Data is scant, but suspicion is growing,
according to Dr. Ronald D. Schultz of the University of Wisconsin Department of
Pathobiological Sciences.
I am a strong advocate of vaccine
use, Dr. Schultz said in the JAVMA article. We need to strike a balance
between those who feel that no vaccines should be given and those who are
vaccinating every week. Annual vaccination has become a knee-jerk response that,
for the most part, is unnecessary. We have come a long way in reducing disease
through vaccination, but perhaps we have gone too far.
How vaccines work
Vaccines stimulate the immune system to
produce antibodies to the disease so that the dog is protected against various
organisms in the environment. If the immunized dog is later exposed to the
infectious agent, the antibodies react quickly to attack and destroy the
disease.
Initial shots are given to puppies to
gradually phase-in immunity as the mothers milk protection wears off. Puppies
are generally vaccinated against parvovirus, distemper, adenovirus (vaccine also
protects against hepatitis), and parainfluenza in combined shots and against
rabies. They may also be vaccinated against leptospirosis, Lyme disease, and
corona virus if local conditions warrant or if the pet will be traveling in an
area where these diseases are known to be a problem.
Vaccines come in two types: killed virus or
bacterin and modified live virus or bacterin. The killed vaccines are mixed with
an adjuvant to boost the effectiveness, and various adjuvants are suspected of
causing problems. Killed vaccines are more stable, but they require more
injections to immunize the pet and are more likely to cause allergic reactions
ranging from low-grade fever or muscle aches to hives, facial swelling, or even
vomiting and diarrhea. In rare cases, a pet may collapse within a few minutes of
the injection from a severe anaphylactic reaction, but most reactions take a day
or more to manifest.
Modified live vaccines work more quickly
and for longer periods, are less expensive, and require only a single dose to be
effective. However, they should not be used in sick animals and may cause
suppression of the immune system in susceptible animals or abortions in pregnant
bitches.
Vaccinations challenge the immune system in
a complex manner, so it is not advisable to vaccinate a puppy or dog that is
sick. Vaccines can fail if the animal has a fever or is taking steroids, or if
they are given too close together or too far apart. They can also fail if the
vaccine has been improperly handled or stored and may not protect a puppy that
has lost immunity from mothers milk before the vaccine is administered.
Despite problems, vaccinations are still a
pet owners best line of defense against distemper and parvovirus that can
kill puppies and young dogs, against rabies that will kill dogs and people
of any age, and against other contagious diseases that can cause short term
and long term health problems.
Pet owners should work with their
veterinarian to design a vaccination schedule for each pet based on age, health
status, reproductive status, and environment. Rotating vaccines so that they are
not all given at once is one option, and titer tests for antibodies is another.
However, titer tests are more expensive than vaccinations and not completely
reliable, so many vets do not recommend them.
If owners do vaccinate a pet and he has a
reaction, it should be reported to the veterinarian and the US Pharmacopeia, a
private organization that operates a reporting program in conjunction with the
American Veterinary Medical Association. USP can be reached at www.usp.org on
the world wide web or at (800) 487-7776.
If pet owners and their veterinarians
decide that other than an annual vaccination is appropriate for particular pets,
owners should get a veterinary statement to that effect if questioned at a
grooming shop, boarding kennel, or training school. Those who plan to board pets
should get the intranasal Bordatella vaccine at least two weeks before vacation
dates, for this vaccine has a shorter period of effectiveness than parvo or
distemper vaccines.
Annual exams
Annual boosters for Fido and Fluffy
is really shorthand for yearly checkup. The veterinarian does far more
than inject the vaccine; he listens to heart and lungs, probes belly, looks at
teeth and gums, examines eyes and ears, checks for parasites and skin disorders,
asks questions, watches the dog move. He discusses ideal weight and exercise if
necessary, and listens to questions and concerns of the owner. Dogs that visit
the veterinarian once a year live longer and are less likely to be surrendered
to a shelter because the owner has an animal health professional to answer
questions and to find potential problems before they become serious. Shot
clinics in pet supply stores do not provide these opportunities.
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