Causes and Risk Factors for Canine Parvovirus
Canine parvovirus is caused by infection with CPV, most often, CPV-2a or CPV-2b. All dogs are at risk for developing canine parvovirus. Puppies less than 4 months old and dogs that have not been vaccinated against the virus are at increased risk for infection.
Newborn puppies receive antibodies from their mothers that help provide immunity, but immunity to CPV wears off before the puppies' immune systems are developed enough to destroy the virus and fight off infection.
Dogs in pet stores, animal shelters, and breeding kennels also are at increased risk. Overcrowding and poor sanitary conditions make it easier for the virus to spread. Certain breeds of dog (e.g., English springer spaniels, rottweilers, Doberman pinschers) and dogs that have another health condition may have a higher risk for developing severe disease.
Signs and Symptoms of Canine Parvovirus
Canine parvovirus is an acute illness, which means that symptoms develop suddenly, usually within 3–10 days of exposure. In most cases, dogs that are infected with the virus do not develop the disease (called asymptomatic infection). Canine parvovirus often is fatal in puppies. Sometimes, puppies collapse and die without showing prior signs of infection.
Signs and symptoms of canine parvovirus include the following:
- Bloody diarrhea (often severe)
- Lethargy (lack of energy)
- Loss of appetite
- Malaise (discomfort associated with illness)
- Rapid weight loss
Without immediate treatment, canine parvovirus often progresses quickly. CPV can cause death within 2–3 days of the onset of symptoms, so it is important to seek veterinary care as soon as possible.
Complications include dehydration, secondary infections, sepsis and a condition in which part of the intestine slips into the part below it (called intussusception). CPV also can damage the spleen. Dogs that have another health condition are at increased risk for developing severe complications and illness.
Canine Parvovirus Diagnosis
Diagnosis of canine parvovirus is based on symptoms, physical examination, and laboratory tests. In puppies and dogs that have not been vaccinated, CPV infection often is suspected when bloody diarrhea, loss of appetite, and vomiting develop suddenly. Physical examination may reveal signs of dehydration (e.g., lethargy, sunken eyes, dry gums, rapid heart rate, concentrated urine), fever, abdominal discomfort, swollen lymph nodes, and weight loss.
Laboratory tests include blood tests (e.g., to detect a low white blood cell count) and other tests to detect the virus (e.g., ELISA, electron microscopy). ELISA (enzyme-linked immunosorbent assay), which detects the presence of the virus in stool, is used most often. In some cases, recent immunization with the live virus can produce a false positive test result.