Parvo in Dogs

Canine parvovirus – also known as “parvo” – is a highly contagious virus that primarily affects young, unvaccinated dogs and puppies.  Parvo is most common in puppies less than 6 months of age, but dogs of any age can be affected.  Parvo is found worldwide and outbreaks of this deadly disease are common.  Fortunately, parvo can be prevented through vaccination.

What is Parvo in Dogs and Puppies?

Canine parvovirus is a highly contagious, potentially fatal viral disease.  Any dog can be affected, but young puppies and unvaccinated dogs are at the highest risk of infection.  The virus attacks rapidly dividing cells in the gastrointestinal tract, lymphoid tissue, and bone marrow.  The result is a destruction of the lining of the intestinal tract and a drop in white blood cell counts.  This leads to profuse diarrhea and a decreased ability for the body to fight off the infection. Untreated dogs can rapidly succumb to dehydration or sepsis.

How Did My Dog Get Parvo?

Parvovirus is ubiquitous, meaning that it is present everywhere.  Infected dogs shed parvovirus in their feces in massive numbers.  This viral shedding begins shortly before the dog begins showing symptoms of the infection and continues for about 14 days after symptoms have resolved.  The virus is very hardy and is resistant to heat, drying, detergents, alcohol, and many disinfectants.  The virus can live outside the host for months to years under the right conditions.

Parvo infection occurs by the fecal-oronasal route.  This means your dog must ingest infected feces to become infected.  It takes a miniscule amount of infected feces to cause an infection – even licking dirt off the paws or eating something off the ground can cause an infection.  Because parvovirus is ubiquitous and lives for long periods in the environment, your dog does not need to come into direct contact with another dog to become infected.

Can Humans Get Parvo?

Humans have their own form of parvovirus, called parvovirus B19.  Parvovirus B19 is different from canine parvovirus and is not contagious to dogs.  Humans cannot get parvo from dogs, and dogs cannot get parvo from humans.  However, humans can transmit parvo from dog-to-dog by carrying the virus on their clothes or skin.

Can Cats Get Parvo From Dogs?

Canine parvovirus closely resembles feline panleukopenia, also known as feline parvovirus.  Feline parvovirus can infect dogs, but it does not cause disease in dogs.  Canine parvovirus can infect cats and does cause disease in cats.  Vaccinating cats for feline panleukopenia protects them from canine parvovirus.

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Symptoms of Parvo

Symptoms of parvo in dogs often come on suddenly and are rapidly progressive.  Parvovirus has an incubation period of approximately 7-14 days, which means it will take approximately one to two weeks for your dog to show symptoms after being infected.  Signs of parvo can vary, but typically include vomiting and diarrhea.  Any unvaccinated puppy with vomiting and diarrhea should be tested for parvo.

Signs of parvo include:

• Vomiting
• Diarrhea, often profuse and bloody
• Loss of appetite
• Depression
• Fever
• Dehydration
• Abdominal pain
• Lethargy
• Pale gums
• Increased respiratory rate
• Weakness

If your dog displays symptoms of parvovirus infection, see your veterinarian right away.  Prompt diagnosis and treatment are necessary to ensure the best possible outcome for your dog.

Diagnosing Parvovirus

To diagnose parvovirus, your veterinarian may recommend some or all of the following tests:

• Physical Examination. Your veterinarian will perform a comprehensive head-to-tail physical examination on your dog, including assessing your dog’s hydration status and taking your dog’s temperature.  Your veterinarian will also ask you questions about your dog’s history, including your dog’s symptoms, vaccination history, and history of exposure to other dogs.
• Fecal Antigen Test (ELISA). This test uses a sample of your dog’s feces to detect canine parvovirus antigen.  This test is widely used to diagnose parvovirus in dogs because it can be quickly performed in the clinic.  False negative results are possible early in the course of infection or if the test is performed more than 10 days post-infection.  False positive results are possible 4-6 days after vaccination with a modified-live canine parvovirus vaccine.
• Blood Work. Your veterinarian may recommend performing a complete blood count and biochemistry panel to assess your dog for abnormalities that can occur secondary to canine parvovirus infection.  Common findings on blood work include anemia, decreased white blood cell counts, decreased platelet count, decreased albumin level, decreased protein level, decreased blood glucose, and electrolyte abnormalities.

Parvo Treatment

There is no cure for parvo in dogs.  The only treatment for parvo is to provide supportive care for the dog while the virus runs its course.  Hospitalization is necessary for the majority of parvo cases.  Without treatment, many dogs with parvovirus die from dehydration and sepsis.  However, with prompt and aggressive treatment, up to 90% of dogs with parvo survive.

Parvo treatment may include:

• Fluid Therapy. Parvo patients are at high risk of dehydration due to fluid losses from profuse diarrhea and vomiting.  Fluid therapy is one of the most important aspects of parvo treatment.  Fluids are administered intravenously (IV) and may include electrolyte supplementation to correct electrolyte imbalances.
• Anti-emetics. Anti-emetic medications such as maropitant or ondansetron may be given subcutaneously (SQ) or intravenously (IV) to reduce nausea and vomiting.
• Analgesics.  Dogs with parvo often experience abdominal pain.  Analgesic medications are often administered to alleviate discomfort.
• Nutritional Therapy. Nutritional support is necessary in parvovirus patients to reduce mortality and speed recovery.  It is not recommended to withhold food from a parvovirus patient even if they are vomiting.  Nutritional support may involve the placement of a nasoesophageal or nasogastric tube to facilitate feeding.
• Antibiotics.  Low white blood cell counts and damage to the intestinal lining can put parvovirus patients at risk for developing sepsis.  Broad spectrum antibiotics may be administered intravenously (IV) to reduce this risk.
• Transfusion Therapy. Some parvovirus patients develop coagulopathies or have severely low levels of albumin, requiring transfusions of fresh frozen plasma.  Blood transfusions may be required for patients who are severely anemic or those experiencing hemorrhage.

Parvovirus treatment can be long and costly.  However, most dogs that survive the initial 3-4 days of symptoms will recover from parvovirus.

How to Prevent Parvo in Dogs

Parvo is a serious disease and can be fatal.  Fortunately, parvo can be prevented through vaccination.  Parvovirus is a core vaccine for dogs, which means it is recommended that all dogs receive this vaccine.  Puppies should begin their vaccination series at around 6-8 weeks of age, with boosters every 2-4 weeks until they reach 16-20 weeks of age.  Your veterinarian will determine the best vaccination schedule for your puppy based on your puppy’s age, previous vaccination history, and health status.

In addition to vaccination, it is recommended that puppies are not taken to public places until they have completed their initial vaccine series.  This is done to reduce their risk of exposure to parvovirus, which is found in the environment wherever infected dogs may have been.  Puppies should not be taken to dog parks, boarding kennels, grooming facilities, daycare, or public areas until they have completed their puppy vaccine series to reduce their risk of contracting parvovirus.

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