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CAUSE.
The disease is caused by a
highly contagious virus that is transmitted mostly by dogs
orally contacting infected feces. Being a virus, they
contain only DNA or RNA, and are not capable of reproducing
unless they invade a cell. Once inside the cell they take over
and force the
cell to produce so many new virus particles that the cell
eventually bursts, releasing these new virus particles into the
bloodstream and
tissues so they can invade other cells. The only thing that can
stop this is the immune system. Viruses are the smallest of know
living
organisms, and can only be seen with special microscopes called
scanning electron microscopes, that cost millions of dollars
(ours is on order).
The parvovirus is extremely small (the Latin word for small is
parvo), just 1 thimble full of stool can contain millions of
virus particles. It is easy
to see why contamination occurs so readily. Incubation period
varies from 5-10 days. As in many viral diseases of the
intestinal tract, some
dogs can pick up the disease and shed the virus without
significant symptoms in themselves. The parvovirus can linger in
the environment
for many months, allowing it to affect many dogs. It can
withstand common household disinfectants (except bleach) and can
withstand
freezing winter temperatures. It can be spread on the hair and
feet of dogs, in addition to shoes, clothes, and eating
utensils. We tend to
see parvo in dogs that have other diseases, especially
intestinal parasites (worms). This might be because these dogs
have immune systems
that are weakened, making them more susceptible to a viral
infection. Also, the parvo virus capitalizes on the fact that
the lining of the
intestines of these dogs with intestinal parasites are damaged
and susceptible to the pavovirus.
SYMPTOMS.
The majority of dogs
presented with parvovirus show signs of fever, lethargy,
vomiting, diarrhea, and lack of appetite. In severe cases the
diarrhea
is very watery and frequently bloody, with a telltale odor.
They are very ill, with significant abdominal pain. The virus
is so strong that it literally
causes the lining of the intestines to slough. It is painful to
eat, and with the severe diarrhea and vomiting that is present,
they rapidly become
dehydrated. They also have a disruption in their electrolytes
(sodium, potassium, chlorine) that adds to the weakness. There
is a complication
that can occur from all the intestinal activity regarding
vomiting and diarrhea. It is called an intussusception, which
is literally a telescoping of
the intestine into itself. This will cause the intestine to
die, resulting in death of the pup. Treatment is surgical,
unfortunately, these pups are
in no shape for surgery. Luckily we do not encounter this very
often, it at all. In the per acute form of this disease the
virus attacks the heart
and causes rapid death. Fortunately, it is rare to encounter
this nowadays.
TREATMENT.
Dogs with parvovirus need
immediate veterinary care because they are usually very sick.
They should not be treated at home if they are
significantly ill. This care involves large amounts of
intravenous fluids, added electrolytes, antibiotics and special
medications to minimize
vomiting. It is common for them to be hospitalized for 5 days.
We will monitor red blood cell counts and protein levels to
determine dogs
that are not responding to routine treatment. If the protein
level becomes low we institute therapy with additional fluids
(called colloids) to
combat the problem. Dogs that continue to decline in spite of
therapy may also need a blood transfusion because they can
become anemic
and deplete their protein. We will also treat the internal
parasites that can be an integral part of this disease. We do
not feed them until they
have gone 24 hours without vomiting. We will send your dog home
if it is eating and not vomiting for 24 hours. We expect it to
have a persistent
soft stool or diarrhea for several days after returning home.
PREVENTION.
As with all infectious
disease, minimizing exposure from infected animals is the most
effective means of prevention. Since infected dogs shed
large amounts of virus in their stool, contamination is always a
possibility. The virus is quite resistant in the environment,
especially in public
areas that are not disinfected. This is a good reason to keep
your pup away from these areas until it is older, worm free, and
had its full series
of dog vaccines. Since this disease occurs mostly in puppies,
worms (internal parasites) and poor nutrition add
susceptibility. Puppies should
be wormed frequently until they are 3 months old. Any dog you
already have in the household before you exposed it to a parvo
dog you brought
in (whether it died or recovered from the parvo) should be
current on its vaccines and should have minimal exposure, if
possible, to the areas
where the parvo dog contaminated. It is rare for an adult dog
that is current on its parvo vaccine (yearly boosters) to get
parvo. If you had a dog
die of parvo, we recommend thorough cleaning with diluted
bleach (l:30 with water, or 4 ounces of Clorox in a gallon of
water) and waiting 1-12
months before introducing a new dog to the area. Spray the yard
as best as possible with a hose and keep new dogs away from the
area for
1-2 months. Never put bleach on your dog. Vaccines are highly
effective. Ideally, we should vaccinate pups every 2 weeks
starting at 6 weeks
of age and lasting until 5 months of age. This is not realistic
for most people though. Fortunately, parvo vaccines given at 8,
12, and 16 weeks
of age are highly effective. Puppies should not be exposed to
other dogs or the feces of other dogs until the vaccine series
is complete. |
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