CANINE PARVOVIRUS
INFECTION

In 1978 dogs of all ages and breeds began to contract a highly contagious viral disease that attacks the intestinal track, white blood cells, and sometimes the heart muscle. This disease, canine parvovirus (CPV) infection, has appeared world-wide.

The infection is spread by contact between dogs and is likely to appear wherever dogs congregate, including dog shows, breeding and boarding kennels, obedience trials, pet shops, animal shelters, parks and playgrounds.

A dog that is confined to a house or yard and is rarely in contact with other dogs is far less likely to be exposed to the virus. CPV infection can only be transmitted to dogs, not to other kinds of animals or people, but animals and people can carry it to dogs.

The source of infection is faecal waste from infected dogs. Large amounts of the virus may be present in the excrement of infected dogs. The virus is resistant to extremes of environment and can survive for long periods. It is readily transmitted on the hair or feet of infected dogs or by contaminated cages, or objects. No other means of transmission is known.

The first signs of CPV infection are depression, loss of appetite, vomiting, and severe diarrhoea. Rectal temperatures may be raised. These signs will usually appear five to seven days after the dog is exposed to the virus. As a first sign of illness, the faeces will generally be light gray or yellow-gray. Sometimes, the first sign will be fluid faeces streaked with blood.

Dogs may dehydrate rapidly due to vomiting and diarrhoea. Some dogs may vomit repeatedly and have projectile and bloody diarrhoea until they die. Others may have loose faeces and recover without complications.

Most deaths occur within 48-72 hours following the onset of the disease. Pups usually have shock-like deaths, occurring from only two days after the onset of illness. A high percentage of pups under five months old used to die from this disease. But with vaccination, these percentages have decreased dramatically.

Puppies between weaning and six months of age are at increased risk of acquiring the disease.

Another form of parvoviral infection is inflammation of the heart (myocarditis) in pups less than three months of age. This syndrome occurs without concurrent diarrhoea because the virus multiplies rapidly in muscle cells of the growing heart.

Pups with parvoviral myocarditis may act depressed and stop suckling shortly before they collapse gasping for breath. Death may follow within minutes. Others die at intervals over the next several days. Pups that survive may have permanent damage to their hearts. They may die from heart failure weeks or months after they have apparently recovered.

A veterinarian will make the diagnosis based on clinical signs, but only after considering other causes of vomiting and diarrhoea. Evidence of rapid spread in a group of dogs is strongly suggestive of CPV infection and may be confirmed by testing the faeces for the virus. There are no specific drugs that kill the virus in an infected dog.

Treatment of CPV infection, which should be started immediately, consists primarily of efforts to combat dehydration by replacing electrolyte and fluid losses, controlling vomiting and diarrhoea, and preventing secondary infections with antibiotics.