Parvo 1

Pet Tales
by Barry B. Burtis D.V.M.

Canine Parvovirus
Eagerly anticipated and precipitating much excitement, he had arrived in his new home just ten days earlier. But this morning the worry and anxiety he was causing was very evident in the strained, hushed tones of his male owner, describing his symptoms. His gentle, soft licking, as she held him tightly cuddled in her arms, could not erase from her face, the fear and concern, his female owner was feeling. Surely, they thought, this just could not be happening. They had already lost a little puppy, previously, to a disease that had begun with signs just like those George was now exhibiting.

George was 11 weeks old, he weighed just 2.5 kilograms. His haircoat was coloured  jet black from the tip of his flat little Pug nose to the end of his curled little Pug tail. George had received 2 sets of initial puppy vaccines and had been in good health when examined by his breeder's veterinarian, earlier in life. Now, sitting on the examination table for his physical exam, he put on a brave face and tried his best to present a cheery attitude. Still, you could tell, he was not feeling the best. Yesterday he had vomited several times.  Afterwards, he was more quiet, withdrawn, not his usual bouncy self and this morning he had shown absolutely no interest in his breakfast. His body temperature was normal and his check-over revealed no specific reason for his problems.

As discussed in my last column, puppies at this age and stage of their life are susceptible to many things that can cause gastro-intestinal upsets - vomiting, diarrhea and changes in appetite. Many times they are simple dietary upsets from which they quickly recover.  It was hoped George would do the same. Nevertheless, there were some more serious diseases that could also be the cause of his illness. Therefore, a blood sample was collected to provide further information about his health status. He was started on a medication to combat vomiting and the nausea he was likely experiencing. In discussion with George's owners it was decided he would be treated as an out-patient, at present. Instructions for his home care were given and a prescription pediatric diet was dispensed.

The next morning George was brought back to the hospital. His owners reported he had seemed quite playful last evening at home, but, he still refused any food and he had vomited a small quantity of watery fluid earlier that morning. Although his blood tests done the day before had been within the normal range, because of his continuing malaise,  further diagnostics were recommended. A small sample of his stool was collected and submitted to the laboratory for parvovirus testing. George was admitted to the hospital for further care and observation and through the day there was no recurrence of vomiting or diarrhea. However, later that afternoon he vomited several times even though he had still not eaten any solid food. At this time an intravenous catheter was installed in a vein in his front leg and he was started on a continuous intravenous fluid transfusion administered via a fluid pump. Antibiotics, anti-emetics, and drugs to decrease nausea were also given intravenously.

Later that evening the lab reported that George's ELISA assay had tested positive for parvovirus. Parvoviral infection remains, for both pet owners and veterinarians, one of the most feared diseases that can afflict dogs.

Illness as a result of infection with this virus can occur in a dog of any age. Most severe illness occurs in pups between 6-16 weeks of age. The disease develops when a susceptible individual takes in the virus by mouth. Over the next 2-4 days virus enters the patient's blood stream and will begin to increase in numbers but the dog will not yet appear sick. Even though not yet ill itself, it may already be shedding virus in its feces that can infect others. This early stage of development occurs in the tonsils, lymph nodes and similar tissue elsewhere in the body and can affect the numbers of white blood cells. Less of these cells can affect the animal's immune system and its ability to respond to infection.  By about the third day post-infection the rapidly growing cells that line the small intestine are infected. This is the part of the dog's body usually most severely affected. Loss of appetite, vomiting, diarrhea and weight loss result. The incubation period for the disease is between 7-14 days.

In addition to the possible life-threatening consequences of the intestinal disease, caused by the virus, there are a number of other deadly complications that can follow infection. Intussusception, a telescoping blockage of the bowel, poisonous toxins that begin to spread throughout the body, shock, blood clotting disorders and acute respiratory problems are some of these dangers.

Aggressive treatment of the disease increases survival  but death rates still approach 30% of infected puppies. George's story will continue in my next column.