Article is brought to you by Animal Wellness Magazine, this is the first of a three part series.

Vaccination:
Which ones do they REALLY NEED, and HOW OFTEN?
by Ann Brightman

When Helena took her new Sheltie puppy, Mick, to the vet for his first
check-up, she felt more than a little anxious when it came time for
him to receive his shots. While she wanted to protect her new friend from
deadly diseases like distemper and parvo, she was also concerned about the
health risks associated with over-vaccination. Although Helena went ahead
with the vaccines and follow-up boosters, she was worried about subjecting
Mick to subsequent annual shots, even though her vet told her she was risking
her dog's health even more by not doing so.

It's a common quandary these days, especially as we hear more and
more about the often devastating side effects of over-vaccination. How do we
prevent our dogs or cats from contracting infectious diseases that can often
be fatal, while also protecting them from the equally serious health
consequences of too many shots? The best strategy is to learn which
vaccines are absolutely necessary (referred to as core vaccines), why they're
needed, and what the minimum requirements are for each to ensure protection
from disease without over-vaccinating.

WHAT ARE CORE VACCINES?
"Core vaccines are those that every dog or cat should receive,
regardless of geographic location or lifestyle," says Dr. Ron Schultz, Professor
and Chair of the Department of Pathological Studies at the University of
Wisconsin-Madison's School of Veterinary Medicine. For dogs, the four
core vaccines are canine distemper (CDV), canine parvovirus-2 (CPV-2),
canine adenovirus-2 (CAV-2) and rabies. Those for cats are feline
panleukopenia or parvovirus (FPV), feline herpesvirus-1 (FHV-1), also referred to as
feline viral rhinotracheitis, feline calicivirus (FCV) and rabies. In this
article, the first in a three-part series, we'll be taking a close-up look at
canine distemper, feline panleukopenia and rabies.

The eight vaccinations listed above are considered core because the
diseases they protect against are distributed over a wide area and have a high
mortality rate. "These vaccinations are absolutely necessary," says
Dr. Schultz. "You want the vaccine to be the first antigens to prime the
immune system. You don't want to leave it up to natural immunization or
exposure." This is because, when compared to the actual disease-causing virus,
the vaccine is a safer way to protect the animal. "If the vaccine is
live, it's attenuated. If it's killed, it can't cause disease," explains Dr. Schultz.

"It's true that many puppies that never see a vet get naturally
immunized by exposure to distemper, as an example, but for every one that gets
vaccinated probably another would have died if the first encounter with distemper
occurred prior to vaccination."

MINIMIZING VACCINATION
Although core vaccines are necessary to protect your companion from
infectious disease, even these do not need to be given on an annual
basis. "That's what we're trying to change," says Dr. Schultz. "What we
recommend is that both puppies and kittens get the core vaccines at least once
at or over the age of 12 weeks." The 12 weeks is significant, because prior
to that, many animals still have passive maternal antibodies that block
immunization, which means they may not respond to the vaccine and are
therefore unprotected against the disease. American Association Hospital
Association (AAHA) guidelines recommend vaccinating again at one
year, and once every three years after that, although even that may not be
necessary.

"I have studies that show duration of immunity at seven to nine years
for all the core vaccines except rabies, and even on an antibody basis I
can show that rabies gives much longer protection than three years," says
Dr. Schultz.

CANINE DISTEMPER (CDV)
CDV is a highly infectious and often fatal disease that attacks the
respiratory, gastrointestinal and central nervous systems. Although
dogs of any age can contract distemper, puppies up to six months of age are
most susceptible to the disease, which can cause a range of symptoms from fever,
loss of appetite and eye inflammation in its early stages, to diarrhea, vomiting,
pneumonia, and neurological complications such as ataxia, seizures and paralysis.

Canine distemper occurs around the world not only among domesticated
dogs, but also in many wild carnivores such as raccoons, skunks and foxes.
"Wildlife is actually now more of a reservoir for distemper than dogs
are," says Dr. Schultz. "The virus is spread mainly by air, or by direct
contact with secretions from the infected animal. The mortality rate among
puppies with distemper is 50% or higher." On the plus side, the distemper
virus is very fragile and easily destroyed by outside influences. "It doesn't
live very long in the environment," says Dr. Schultz. "It dies very quickly
because it is what we call an enveloped virus. These kinds of viruses
are highly susceptible to water, disinfectant and sunlight."

Although there is only one distemper serotype, there are several
genotypes. "What this means is that, from an immunologic standpoint, it doesn't
matter which distemper infects the animal, they're all similar; the vaccine
for canine distemper can protect against the different genotypes." Dr.
Schultz adds that modified live vaccines (MLV) are most effective for
distemper. "In fact there's no question in my mind that you should be using live
vaccines for most of the cores. Although attenuated, live vaccines infect and
replicate, and that's how you get immunity."

Although AAHA recommends vaccinating against distemper every three
years after the initial puppy shots, challenge studies have shown that the
minimum duration of immunity can last five to seven years, and perhaps even
longer. In fact, titers have indicated that dogs can be protected for nine to
15 years. "To be honest, although canine distemper is a core vaccine, I
think a dog only needs to receive it once in his life," says Dr.
Schultz. "The same goes for canine parvo and adenovirus-2. That's the vaccination
program I've been practicing on my own dogs without any difficulty whatsoever.
We've never had a vaccine-preventable disease occur."

Titer testing is highly effective for canine distemper, but according
to Dr. Schultz, the best time to do it is at two weeks or more after the
last puppy vaccination, to ensure that the animal responded to its initial
vaccines. "To my mind, that's the only time it's of medical benefit to use a
titer test for canine distemper. After that, you don't really need to titer
the animal since you can easily go five or seven years before the next
vaccine."

FELINE PANLEUKOPENIA (FPV)
Although FPV is sometimes referred to as feline distemper, this
terminology is misleading. "When I talk about feline `distemper,' I always talk
about it as feline parvo or panleukopenia," explains Dr. Schultz. "The virus
that causes this disease is essentially identical to the canine parvo virus, but not
the canine distemper virus. If a dog has parvo, it can infect a cat, but this
doesn't happen with distemper "

Most often found in kittens, FPV is a contagious and deadly disease
that attacks and destroys growing cells in the intestine, blood and nervous
system. It causes diarrhea, vomiting, a lowered white blood cell
count, and neurological symptoms such as tremors. Kittens up to six months of
age can easily die from the disease, while older cats may develop much milder
signs. "There's a tremendous age-related resistance to parvo," says Dr.
Schultz. "If the animal is less than a year old, mortality is 80% to 100%.
However, I rarely see mortality in animals over a year of age, although I might
see mild morbidity. Nevertheless, feline parvo is the one cat vaccin4e I
absolutely insist on."

Like canine distemper, feline parvo has worldwide distribution with
outbreaks occurring most commonly in urban areas during the summer
months. The disease is transmitted by direct contact, although cats can also
contract FPV from the fecal matter of an infected feline. Unlike
canine distemper, the parvo virus is extremely long-lived, and can remain
active in the environment for months or even longer. "Parvo is what we call a
naked virus and is one of the most resistant," says Dr. Schultz. Soil
contaminated with the parvo virus still has the ability to infect an animal a year
later. "In fact, parvo is more often caused by environmental contamination
than direct contact with an infected animal. You don't need the infected
cat to be in the environment for very long in order for it to leave the virus
behind."

As with canine distemper, MLV vaccines are very effective for
preventing feline panleukopenia. "With parvo, in fact, you'd better be using live
vaccines, because the killeds don't work." As with other core
vaccines, kittens should be vaccinated at 12 weeks. Titer testing is very
effective for this disease, although challenge studies indicate that a
vaccinated kitten can remain protected from feline parvo for eight years.

RABIES (RV)
Unlike distemper and parvo, rabies is a disease that can be
transmitted from animals to humans, which is why rabies vaccinations are required by
law throughout North America. The virus infects the central nervous
system, causing encephalitis and death. Symptoms can include confusion,
partial paralysis, aggressive behavior, excessive salivation and other
neurological signs. Although rabies occurs worldwide, including in Asia, Africa
and Latin America, some countries such as the U.K. are rabies-free. In North
America, rabies is most prevalent in the eastern portions of the continent,
although cases can occur anywhere. Wild animals such as raccoons, skunks, bats
and foxes are the major carriers. Because rabies isn't age-related,
mammals at all stages of life can be affected with the same degree of severity.

The chief means of transmission is by a bite from an infected animal.
"There are multiple strains of rabies, but the important thing is
that the vaccine prevents infection with all those different strains," says Dr.
Schultz. "Although the risk of infection in domesticated animals is
generally low, the public health concern is the issue. That's what
drives the regulations for rabies vaccines." As with the other core vaccines,
puppies and kittens should be vaccinated at 12 weeks. Although some
states and provinces have approved a three-year rabies vaccine, some still
require annual re-vaccination for dogs and cats, even though the duration of
immunity based on challenge studies has been shown to be three to
seven years. "The regulations vary from state to state and province to
province, and even from municipality to municipality." It's also important to
realize that a municipality might have a more restrictive requirement than
the state or province it's a part of, although not the other way around.

"Rabies titers are effective, but there's no point running them
because you're going to have to vaccinate your animal by law anyhow," says Dr.
Schultz. However, titer testing for rabies is useful in cases where
the animal has had an adverse reaction to the vaccine, or has a medical
condition that could be aggravated by the vaccination. "In these
situations, local municipalities will sometimes accept a letter from the vet as a
reason not to vaccinate every three years, But the guardian has to
understand that the animal is still considered to be non-vaccinated, and if it bit
someone, it would be treated as such if it's gone beyond the three years,
irrespective of the vet's letter. Even so, if you have a dog that for
health reasons shouldn't be given a rabies vaccine, it's better to take the chance
of it being quarantined for biting someone than to give the vaccine and
kill the dog."

BACK TO BASICS
Vaccinations definitely have their place in disease prevention, but
knowing where to draw the line is key. "I've seen it go from no vaccines back
in the mid-1960s, to where we just kept adding one after the other," says Dr.
Schultz. The pendulum has since started swinging back again as
organizations such as AAHA and American Association of Feline Practitioners (AAFP)
began looking more closely at which vaccines out of the 12 for cats and 16
for dogs were really needed and why. "We used to have one manufacturer
that made a canine vaccine combo with 13 different components in it. That's not
good, and that's why it's not available anymore." Now, by contrast,
companies are coming out with information demonstrating that their products give
duration of immunity lasting several years. "All the major manufacturers are
coming on board and saying that their core vaccines give at least three years
immunity. To me, that's the greatest gratification in the more than
25 years I've been doing this."

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