Canine parvovirus: how can we protect puppies?

Epidemiology

Canine parvovirus is transmitted orally. It is highly resistant to environmental stresses.

The virus mainly affects young dogs after they lose maternal immunity, i.e. from the age of 6 weeks on. Parvovirus occurs less frequently in adults because they have already been vaccinated or had subclinical infections. It has an incubation period of approximately 5 days.

Clinical signs

The characteristic clinical signs of parvovirus are the acute onset of anorexia, vomiting and depression. This is followed by profuse, bloody diarrhoea coursing with dehydration and fever.

Jaundice or even disseminated intravascular coagulation (DIC) with hypovolemic and/or endotoxic shock may occur in the most severe cases.

Laboratory tests reveal marked leukopaenia of 500–2,000 leukocytes/µL. Air often accumulates in the gut due to paralytic ileus. This should not be mistaken for a bowel obstruction.

Treatment

The main focus of parvovirus treatment is to prevent dehydration by establishing fluid therapy. This can be done with Ringer’s lactate solution plus KCl. Dextrose can be added in the case of hypoglycaemic patients. Any dogs that develop sepsis will require antibiotic therapy with amoxicillin or first-generation cephalosporins.

Vomiting should be treated with a bolus or constant rate infusion of an antiemetic such as metoclopramide. The addition of a H2-receptor antagonist such as ranitidine is also useful.

The patient must adhere to strict fasting until they have passed 24 hours free from vomiting or melena. Any animals with severe hypovolaemia or hypoproteinaemia will require a transfusion.

After 3–5 days and with signs of clinical improvement, a soft diet can be gradually introduced.

Prognosis

With good monitoring and the early initiation of treatment, it has an excellent prognosis. It is worth remembering that lots of puppies died from canine parvovirus infection in the 1980s.

Prevention

Parvovirus infection can be prevented through vaccinations. The problem is the period when puppies are 6–8 weeks old, when maternal immunity is still strong enough to inactivate vaccines, but too weak to provide effective protection against parvovirus infection.

Hence the specific need to use other strategies to protect puppies such as immunonutrition, which we have discussed in previous posts. Since puppies have immature immune systems, they have special dietary needs.