Dog - Parvovirus Infection

What is canine parvovirus disease?

Canine parvovirus (CPV) disease first appeared in 1978.  Due to the severity of the disease and its rapid spread through the canine population in Britain in the 1980s, CPV aroused a great deal of public interest.  The virus that causes the disease is very similar to that which causes feline enteritis.  The two diseases are almost identical.  Therefore, it has been speculated that the canine virus is a mutation of the feline virus, although this has never been proven.

How does a dog become infected with parvovirus?

The causative virus is carried in high concentration in the faeces of infected dogs.  Susceptible animals become infected by contact with the virus which is then carried to the intestine where it invades the intestinal wall and causes inflammation.

Unlike most viruses, CPV is very stable in the environment.  It is resistant to the effects of heat, detergents, and alcohol.  CPV has been recovered from dog faeces even after three months at room temperature.  Due to this stability, the virus is easily transmitted via the hair coat or feet of infected dogs and contaminated shoes, clothes, and other objects.  Direct contact between dogs is not required to spread the disease.  Dogs that become infected with the virus and go on to show clinical signs will usually become ill within 7-10 days of initial infection.

How does this disease affect the dog?

The clinical signs of CPV disease are variable. Generally severe vomiting and diarrhoea occur.  The diarrhoea may or may not contain blood.  Additionally, affected dogs often exhibit a lack of appetite, depression and fever.  Many dogs may not show every clinical sign, but vomiting and diarrhoea are the most common signs; vomiting usually begins first.  CPV may affect dogs of all ages but is most common in dogs less than one year of age (or very elderly, unvaccinated dogs).  Young puppies less than 5 months of age are often the most severely affected and the most difficult to treat successfully.

How is it diagnosed?

The clinical signs of CPV infection often mimic other diseases which cause vomiting and diarrhoea.  Consequently, diagnosis of CPV is often a challenge for the veterinary surgeon.  The positive confirmation of CPV infection requires the demonstration of the virus in the faeces or the detection of CPV antibodies in the blood serum.  Occasionally, a dog will have parvovirus but test negative for virus in the faeces.  Fortunately, this is not a common occurrence.  A tentative diagnosis is often based on the presence of a reduced white blood cell count (leukopaenia) although its absence does not rule out the condition.  If further confirmation is needed, faeces or blood can be submitted to a veterinary laboratory for further tests.

Can it be treated successfully?

Modern antiviral drugs are often employed but are not 100% effective.  However, the virus does not directly cause death; rather, it causes the loss of the lining of the intestinal tract.  This results in severe dehydration, electrolyte (sodium and potassium) imbalances, and infection in the bloodstream (septicaemia).  It is this septicaemia which usually results in the dog's death.

What does treatment involve?

The first step is to correct dehydration and electrolyte imbalances.  This requires the administration of intravenous fluids (a drip) containing electrolytes.  Antibiotics and anti-inflammatory drugs are also given to prevent or control septicemia.  Antispasmodic drugs are used to inhibit the diarrhoea and vomiting that perpetuate the problems.

What is the survival rate?

Most dogs with CPV infection recover if aggressive treatment is used and if therapy is begun before severe septicaemia and dehydration occur.  For reasons not fully understood, some breeds (notably the Rottweiler) have a much higher fatality rate than other breeds.

Can it be prevented?

The best method of protecting your dog against CPV infection is appropriate vaccination.  Puppies should receive CPV vaccination as part of the vaccine course commenced from 6-8 weeks of age.  In 'high risk' situations the vaccine will be repeated at two week intervals from 6-12 weeks with an additional booster at 18-20 weeks of age.  After initial vaccination all dogs should be boosted according to the manufacturer's recommendations.  Pregnant bitches should be boosted before mating or immediately after whelping in order to transfer protective antibodies to the puppies. Unfortunatly, if your puppy has already been infected with with the virus before receiving the vaccine, it is unlikely to be protected. We do sometimes see cases of parvovirus in puppies who have yet to complete their vaccination course.

Is there a way to kill the virus in the environment?

The stability of the CPV in the environment makes it important to properly disinfect contaminated areas.  This can be accomplished by cleaning food bowls, water bowls, and other contaminated items with a solution of one cup of chlorine bleach in a gallon of water (250 ml in 5 litres of water).  This is a cheap and effective parvoviricidal disinfectant although today other very effective preparations are available.  We will be happy to advise.  Many 'viricidal' disinfectants will not kill canine parvovirus.

Does parvovirus pose a health risk for me?  How about for my cats?

It is important to note that, at the present time, there is no evidence to indicate that CPV is transmissible to either cats or humans.