Canine Parvovirus Infection

What is Canine Parvovirus Infection?

Canine Parvovirus (CPV) infection first appeared in 1978. Due to the severity of the disease and its rapid spread through the canine population, CPV has aroused a great deal of public interest. The virus that causes the infection is very similar to Feline Enteritis in cats, and the two diseases are almost identical. Therefore, it has been speculated that the CPV is a mutant of the feline virus. However, that has never been proven.

How Does a Dog Become Infected with Parvovirus?

The causative agent of CPV infection, as the name infers, is a virus. The main source of the virus is the faeces of infected dogs. The faeces of an infected dog can have a very high concentration of viral particles. Susceptible dogs become infected by ingesting the virus. Subsequently, the virus is carried to the intestine where it invades the intestinal wall and causes inflammation.

Unlike most other viruses, CPV is stable in the environment and 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 its stability, the virus is easily transmitted via the hair or feet of infected dogs, contaminated shoes, clothes and other objects. Direct contact between dogs is not required to spread the virus.

Dogs that are infected with the virus usually become ill within 7 to 10 days of the initial infection.

How Does this Disease Affect the Dog?

The clinical manifestations of CPV infection are somewhat variable, but generally take the form of severe vomiting and diarrhoea. The diarrhoea may or may not contain blood. Additionally, affected dogs often exhibit a lack of appetite, depression and fever. It is important to note that many dogs may not show all clinical signs, but vomiting and diarrhoea are the most common signs; vomiting usually begins first.

Parvovirus may affect dogs of all ages, but is most common in dogs less than one year of age. Young puppies less than five months of age are often the most severely affected and the most difficult to treat.

How is CPV Infection Diagnosed?

The clinical signs of CPV infection can mimic other diseases that cause vomiting and diarrhoea; consequently, the diagnosis of CPV infection is often a challenge for the veterinarians. The positive confirmation of CPV infection requires the demonstration of the virus in the faeces or the detection of anti-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 reduced white blood cell count (leukopaenia). If further confirmation is needed, faeces or blood can be submitted to a veterinary laboratory for the other tests. The absence of leukopaenia does not always mean that the dog cannot have CPV infection. Some dogs that become clinically ill may not necessarily be leukopaenic.

Can CPV Infection be Treated Successfully?

As with any viral disease, there is no treatment to kill the virus once it infects the dog. However, the virus does not directly cause death; rather, it causes loss of the lining of the intestinal tract. This results in severe loss of water through diarrhoea, electrolyte (sodium and potassium) imbalances, and infection in the blood stream (septicaemia). The occurrence of septicaemia is due to the entry of bacteria that normally live in the intestinal tract into the blood stream through the damaged lining. The dog is more likely will die then.

The first step in treatment is to correct dehydration and electrolyte imbalances. This requires the administration of intravenous fluids containing electrolytes. Antibiotics and anti-inflammatory drugs are also given to prevent or control septicaemia. Further, 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 begins before severe dehydration and septicaemia occur. For reasons not fully understood, some breeds, notably the Rottweiler, have a much higher fatality rate than other breeds.

Can CPV Infection be Prevented?

The best method in protecting your dogs against CPV infection is proper vaccination. Puppies receive Parvovirus vaccination as part of the vaccines given at 6 to 8 weeks, 12 to 14 weeks and 16 to 18 weeks. After the initial series of vaccinations when the dog is a puppy, all dogs must be boosted once a year. Bitches must be boosted before mating or immediately before whelping in order to transfer protective antibodies to the puppies. The final decision about a proper vaccination schedule should be made by your veterinarian.

How 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 possible contaminated items with a solution of 250 ml of chlorine bleach in 5 litres of water. It is important that chlorine bleach (or glutaraldehyde based disinfectants) is used because many other "viricidal" disinfectants will not kill the CPV.

Does CPV Pose a Health Risk for Dog Owners? How About for the Cats Living in the Same House?

Currently, there is no evidence to indicate that CPV is transmissible to humans or cats.