Parvovirus

Parvovirus is a prevalent and deadly disease spread from dog to dog through direct or indirect contact with feces.  The virus attacks rapidly dividing cells in the body, which leads to a severe bloody diarrhea and a dangerously low white blood cell count.  Other clinical signs include vomiting, anorexia and lethargy.  The cardiovascular form (seen when parvo is contracted in utero or within the first 8 weeks of life) can cause respiratory or heart failure in young dogs and is generally causes death rapidly.

The most commonly affected by parvovirus are young puppies, who are most susceptible to the disease and often unvaccinated. Even puppies that are vaccinated can still be at risk, as maternal antibodies can eliminate the vaccine protection from the puppy’s system before the next vaccination is due.  Maternal antibodies are the antibodies present in the mother's milk during the first 24 hours after the puppy's birth. The age at which puppies can effectively be immunized is proportional to the titer of the mother and the effectiveness of transfer of maternal antibody within those first 24 hours. High levels of maternal antibodies present in the puppies' bloodstream will block the effectiveness of a vaccine. When the maternal antibodies drop to a low enough level in the puppy, immunization by a commercial vaccine will work. The complicating factor is that there is a period of time from several days to several weeks in which the maternal antibodies are too low to provide protection against the disease, but too high to allow the vaccine to work. This is the time when despite being vaccinated, a puppy can still contract parvovirus. The length and timing of the window of susceptibility is different in every puppy in every litter.

While vaccination cannot guarantee 100% coverage, we do our best to limit the potential for contraction of the disease through vaccination.  The recommended protocol is to vaccinate puppies against parvovirus beginning at 6-8 weeks of age, and revaccinating every 3 weeks until the puppy is 16 weeks of age. A booster is given at one year of age and every 2-3 years thereafter, depending on exposure. 

Parvovirus is a very difficult virus to kill, and can live in the environment and on materials such as clothing and bedding for months.  The only household cleaning agent that can kill parvovirus is bleach, although there are equally-effective, more environmentally friendly options available.

Philadelphia is a high risk area for parvovirus infection - it is strongly recommended that puppies be kept in a very limited location where other potentially unvaccinated dogs have not been and cannot go, until they have received their final vaccination at 4 months of age.  While it is safe to be with other vaccinated dogs and puppies, the location (such as a park or even the sidewalk) can still harbor parvovirus.

Treatment of parvovirus requires hospitalization in most cases - the mortality rate without treatment can be as high as 90%.  Supportive care including intravenous fluid therapy, gi protectants and antibiotic coverage to prevent secondary bacterial infection is generally required in all cases.  Some patients require further support including plasma or blood transfusions.  With early detection and aggressive therapy, survival rates can be as high as 80-95%.