Canine Parvovirus

 

What is Canine Parvovirus?

Canine parvovirus (CPV) is a highly contagious viral disease that affects dogs. The common form of this virus affects a dog’s gastrointestinal tract. Dogs of all ages are susceptible to CPV, however the majority of the cases are usually seen in puppies between 6 weeks and 6 months of age. Dogs with suppressed immune systems and dogs that are un-vaccinated or not completely vaccinated are also at risk of contracting the virus. Most deaths from CPV happen within 48 to 72 hours following the onset of clinical signs. Without treatment, prognosis for recovery is very guarded for this disease. Some “black and brown” breeds seem to be more susceptible to CPV than others. Breeds such as Rottweilers, Pit Bulls, Labrador Retrievers, Doberman Pinschers, German Shepherds and English Springer Spaniels may be recommended to have additional boosters in their vaccination schedule.

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What are the symptoms of Canine Parvovirus?

Once the virus is in the bloodstream, the virus targets rapidly dividing cells hitting hardest in the bone marrow and in the cells that line the walls of the small intestine.

In the bone marrow, the virus weakens the body’s ability to protect itself. The virus impedes the body’s ability to produce new white blood cells to fight infection.

In the intestinal tract, the virus damages the cells that line the wall of the small intestine. When this happens, an infected dog cannot properly absorb food or water, which causes dehydration and malnutrition. Also, as the intestinal lining becomes more and more damaged, normal bacteria from the intestinal tract are able to gain access to the bloodstream which leads to a secondary septicemia.

The combination of low levels of white blood cells (decreased immunity), dehydration, malnutrition and secondary bacterial infection creates a deadly situation for the dog.

Symptoms of parvovirus include:

  • Fever

  • Lethargy

  • Vomiting

  • Diarrhea (often bloody)

  • Decreased appetite and anorexia

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How is Canine Parvovirus diagnosed?

Diagnosing parvovirus is usually based on the dog’s medical history, vaccination status, clinical signs, physical exam and laboratory testing. A dog with a history of exposure to an infected dog or lack of their own vaccination with the visible signs of illness may be suspected of having parvo.

Direct testing for CPV is available by testing for the presence of canine parvovirus antigen in canine feces. This test is quick and convenient, as most veterinary clinics can run them in clinic. This test can detect the antigens early in the course of infection, before the virus becomes wide spread. A complete blood cell count (CBC) will also be done upon diagnosis and during treatment to monitor the dog’s white blood cell (WBC) count. Dogs with parvovirus will commonly have an accompanying low WBC count because of the virus’ effects on the bone marrow. Fecal testing for intestinal parasites is usually also recommended. Puppies or dogs carrying an intestinal parasite burden will have a more difficult time recovering as the parasites will put additional stress on to the already severely damaged intestinal tract. This makes it important to rule out parasites or treat for them alongside the CPV infection.

How is Canine Parvovirus treated and prevented?

Since it is a virus that causes CPV, there is no specific drug that can cure it. Treatment is centered on supportive care. This means that the secondary problems that come up in the course of the infection are addressed individually with the goal of keeping the patient alive long enough for an immune response to generate. Hospitalization, isolation and intensive care is needed to treat CPV.

Treatment will include:

  • IV fluid therapy: to replace the fluid losses from vomiting and diarrhea

  • Antibiotic therapy:  to prevent or treat secondary bacterial infections

  • Anti-emetics: to control nausea and vomiting

  • Anti-parasitics: to treat an intestinal parasitic burden if present

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Vaccination is available against canine parvovirus, it is part of the DA2PP core vaccine given to dogs (the “P” in the vaccine name stands for parvovirus). Canine parvovirus is preventable with the appropriate vaccination schedule. Vaccination should start in puppies at 8 weeks of age then boostered at 12 weeks. Puppies vaccinated earlier than 8 weeks may need a third booster to make sure proper immunity is obtained. Vaccination is repeated one year later, then changes to a 3-year vaccination schedule.

A dog infected with parvovirus will shed the virus for 4-5 days before they start showing clinical signs. Shedding of the virus will continue for 3-6 weeks after the initial infection. The shedded virus is very hard to eradicate and stays in the environment for a very long time. It can survive hot, cold and freezing temperatures, meaning that the winter weather does not kill it and it becomes active again in the spring. The virus can survive in the environment for up to a year. It is also a hard virus to kill with cleaning, as it is resistant to most cleaners. Using a 1 in 30 bleach dilution and allowing all surfaces to soak in this bleach for 10-15 minutes is the best way to clean and disinfect an area of the virus.