- Canine parvovirus (CPV) disease is
currently the most common
- infectious disorder of dogs in the
- 'Parvo' is a highly contagious disease
characterized by diarrhea that is often bloody. Prior to 1980, most canine parvovirus that caused disease was Type 2 (CPV-2).
After 1980, CPV-2 was replaced by CPV-2a became more common and in 1986, another variation
called CPV-2b appeared. In the past few years, a new strain, CPV-2c has been detected.
Today, CPV-2b has largely replaced the previous strains as the most common parvovirus
causing disease in the dog. There is currently some discussion that there may be other
strains that are beginning to emerge and have yet to be formally identified. Current
vaccinations have helped to control the spread of this disease but despite being
vaccinated, some dogs still contract and die from parvo. There is much that we do not know
about the virus or the best way to control the disease, but we are learning new
information daily. Misinformation about the disease, its spread, and vaccination is
widespread. We hope that with a better understanding of the disease, pet owners will be
able to make good health decisions for their dogs that will help prevent and reduce the
spread of this disease.
How is parvovirus spread?
Parvovirus is spread through contact with
feces containing the virus. The virus is known to survive on inanimate objects - such as
clothing, food pans, and cage floors - for 5 months and longer in the right conditions.
Insects and rodents may also serve as vectors playing an important role in the
transmission of the disease. This means any fecal material or vomit needs to be removed
with a detergent before the bleach solution is used. The bleach solution should be used on
bedding, dishes, kennel floors and other impervious materials that may be contaminated.
The normal incubation period (time from
exposure to the virus to the time when signs of disease appear) is from 7-14 days. Active
excretion of the virus in the feces can begin the third day after exposure, often before
clinical signs appear, and may last for one to two weeks after the onset of the disease.
What are the symptoms of parvovirus
There is a broad range in the
severity of symptoms shown by dogs that are infected with parvovirus. Many adult dogs
exposed to the virus show very few, if any, symptoms. The majority of cases of disease are
seen in dogs less than 6 months of age with the most severe cases seen in puppies younger
than 12 weeks of age. There are also significant differences in response to parvovirus
infections and vaccines among different breeds of dogs, with Rottweilers, Doberman
Pinschers, and Labrador Retrievers being more susceptible than other breeds.
The most common form of the disease is the
intestinal form known as enteritis. Parvovirus enteritis is characterized by vomiting
(often severe), diarrhea, dehydration, dark or bloody feces, and in severe cases, fever
and lowered white blood cell counts. Acute parvovirus enteritis can be seen in dogs of any
breed, sex, or age. The disease will progress very rapidly and death can occur as early as
two days after the onset of the disease. The presence of gram negative bacteria,
parasites, or other viruses can worsen the severity of the disease and slow recovery.
A less common form of the disease causes
myocarditis (inflammation of the heart).
How is parvovirus infection diagnosed?
Not all cases of bloody diarrhea with or
without vomiting are caused by parvovirus and many sick puppies are misdiagnosed as having
'parvo.' The only way to know if a dog has parvovirus is through a positive diagnostic
test. In addition to the more time consuming and expensive traditional testing of the
blood for titers, a simpler test of the feces with an enzyme-linked immunosorbent assay
antigen test (ELISA), commonly called the CITE test, is also available through most
veterinary clinics. Testing of all suspect cases of parvo is the only way to correctly
diagnose and treat this disease. A complete physical exam and additional laboratory tests
such as a CBC and Chem Panel help to determine the severity of the disease.
How is parvovirus disease treated?
The treatment of parvovirus is fairly
straightforward and directed at supportive therapy. Replacing fluids lost through vomiting
and diarrhea is probably the single most important treatment. I.V. administration of a
balanced electrolyte solution is preferred, but in less severe cases, SubQ or oral fluids
may be used. In severe cases, blood transfusions may be necessary. Antibiotic therapy is
usually given to help control secondary bacterial infections. In those dogs who have
severe symptoms, antiserum against endotoxins may be given. Corticosteroids may be given
if the animal is in shock. In cases of severe vomiting, drugs to slow the vomiting may
also be used. After the intestinal symptoms begin to subside, a broad spectrum de-worming
agent is often used. Restricting the food during periods of vomiting is also necessary and
parenternal nutrition (providing nutrients intravenously) may be necessary.
Undertaking the treatment of affected dogs
and puppies without professional veterinary care is very difficult. Even with the best
available care, the mortality of severely infected animals is high. Without the correct
amount of properly balanced intravenous fluids, the chance of recovery in a severely
stricken animal is very small.
All parvoviruses are extremely stable and
are resistant to adverse environmental influences such as low pH and high heat. Exposure
to ultraviolet light and sodium hypochlorite (a 1:32 dilution of household bleach - ½ cup
bleach to 1 gallon of water) can inactivate parvovirus. The bleach solution can be
impaired by organic matter and needs to have adequate exposure time and proper
concentrations to work effectively.
Immunity and vaccination
If a puppy recovers from parvovirus
infection, he is immune to reinfection for probably at least twenty months and possibly
for life. In addition, after recovery the virus is not shed in the feces. There are many
commercially prepared attenuated (modified) live CPV-2 vaccines available. Although some
people have expressed concern about the possibility of modified live vaccines reverting to
a virulent strain after being given and then causing disease, studies have repeatedly
shown that this does not occur. Commercially prepared vaccines are safe and do not cause