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Canine Parvovirus


What is Canine Parvovirus?

Canine parvovirus is one of the most serious illnesses your puppy may face! If untreated, it is almost always fatal, but it can be prevented with vaccination and by limiting exposure.

Parvoviruses are a group of viruses that affect almost all mammalian species. They are non-enveloped which means they persist in the environment for a long time. They are also species specific, which means the dog parvovirus will not infect cats or people and vice-versa. Cats also have a parvovirus which is particularly deadly called feline panleukopeina.

The first canine parvovirus was discovered in 1967, but only affected newborn puppies. In 1978, a much more deadly variant (canine parvovirus 2 or CPV-2) arrived on the scene and lead to the death of thousands of dogs. Some believe this virus originated as a mutation from the cat parvovirus, panleukopenia. Since the arrival of CPV-2, several new variants have developed – CPV-2a, CPV-2b, and CPV-2c. Today’s canine vaccine protects your dog from all variants.

How would a dog become infected with parvovirus?

As mentioned above, canine parvovirus is non-enveloped which means it can survive in the environment for long periods of time. It is resistant to the effects of detergents, alcohol, and many disinfectants. Sick dogs generally suffer from a fair amount of either vomiting and/or diarrhea, which is loaded with parvovirus. Dogs are generally infected when they come in contact with the diarrhea or vomit from an infected dog. The virus can easily be transferred to the dog’s fur, contaminated shoes, clothes, and other objects which can spread the virus. Direct dog to dog contact is NOT required for spread! During an infection, dogs shed the virus for approximately 14 days.

What signs would I see if my dog was sick?

After becoming infected with the virus, it is generally 7-10 days before clinical signs show. The most common signs we see are vomiting, diarrhea, and lethargy. The diarrhea and vomit may or may not contain blood. Most dogs are tired, have poor appetites, and may have fevers. Because of the success of vaccination, most dogs that become sick are puppies less than one year old. Older dogs that have not been vaccinated are also at risk of being infected.

The virus attacks rapidly dividing cells – generally the cells lining the gastrointestinal tract and the white blood cells in the bone marrow. In the gastrointestinal tract, the damage results in fluid loss (or dehydration), electrolyte imbalances, protein loss, and septicemia (bacteria present in the gut enter the bloodstream). This can lead to widespread infection. At the same time, the virus is attacking the dog’s immune fighting white blood cells in the bone marrow. Dogs that die from parvovirus generally die from dehydration or infection. Survival is the race between dog’s damaged immune system trying to recover and respond versus the fluid loss and bacterial invasion caused by the virus.

How is parvovirus diagnosed?

Fortunately, a very accurate test is available which looks for the presence of the virus in the feces. Infected dogs generally start shedding the virus in their feces 4 days after infection and the peak of viral shedding tends to happen when clinical signs first occur. The test is easy to perform in the clinic from a fecal sample and results are available in 10 minutes.

How do you treat parvovirus?

Similar to other viruses, we do not have a way to kill parvovirus. Our only way of treating parvo is by supportive care, allowing the dog’s immune system to overcome the virus. With aggressive care and hospitalization, survival rates approach 80%.

The basics of treatment involve:

  • Fluid Therapy – we place intravenous catheters and administer fluids to keep the patient hydrated and to correct any electrolyte imbalances.
  • Antibiotics – we use a combination of antibiotics to keep bacteria which enters the body from travelling through the bloodstream. We can generally administer these antibiotics by injection rather than orally.
  • Anti-Nausea/Anti-Emetic – It is important to stop the fluid loss due to vomiting by administering an anti-emetic. Dogs also feel much better when we keep their nausea to a minimum. Most commonly, we use Cerenia (maropitant) or Reglan (metoclopramide).
  • Gastroprotectants – Sometimes we use acid blockers or coating agents to help soothe the gastrointestinal tract and to decrease the chance of ulceration.
  • Hospitalization – While we administer this supportive care, affected dogs are hospitalized in our isolation ward. The average length of hospitalization is 4-5 days, although this varies. The dogs are monitored and checked many times daily and supportive care is customized for each patient. Complications other than above can occur and may require additional treatment. Our isolation ward ensures that the puppies receive the best care, without compromising the health and safety of our other patients. Below are pictures of the isolation ward which is just off our treatment area and easily visible through glass windows.

How do I prevent parvovirus?

Fortunately, an excellent vaccine exists which can protect your puppy or adult dog from parvovirus. Parvovirus is included in our regular series of puppy vaccines generally administered at 8, 12, and 16 weeks of age.

Even with proper vaccination, a puppy may still be at risk! When puppies are born, they receive antibodies from their mother that help protect them. Over time, these antibodies gradually diminish in their system, and the puppy starts generating his/her own antibodies. There is a critical period when the maternal antibodies are dropping and before the puppy has adequate protection; this is when infection can happen in vaccinated puppies. Vaccination boosts the puppy’s production of antibodies to hopefully minimize this “at risk” period, when they could potentially be infected.

It is impossible to know when a puppy is in their “at risk” window so we recommend carefully controlling their environment. Do not take your puppy to any outdoor public areas such as dog parks, pet stores, parks until the vaccination series is complete at 16 weeks!

How do I disinfect my home?

Because parvovirus is such a hardy virus, it is very difficult to kill in the environment. The best solution for disinfection is bleach:water at a 1:10 ratio on all hard surfaces that won’t be damaged by this strong solution. Any items that can be laundered should be washed on HOT with BLEACH. Steam cleaners should be used on the carpet, but may not eliminate the virus. The outside environment is nearly impossible to disinfect.

Are my other pets at risk?

Adult dogs that are up to date on their vaccines are generally protected from infection with parvovirus. We continue to vaccinate adult dogs every 3 years for parvovirus according to recommendations by the American Animal Hospital Association.

As mentioned above, canine parvovirus is specific to dogs and will not infect you or any cats in your household.