Canine Parvovirus: A Potentially Fatal Threat to Your Dog

Canine parvovirus is one of the most serious disease threats for dogs, especially for puppies and young dogs. It is caused by a virus that infects the intestinal tract. The disease caused by the canine parvovirus is frequently called “parvo.”

How Do Dogs Get Parvovirus?

Canine Parvovirus: A Potentially Fatal Threat to Your Dog Dogs are exposed to parvovirus when they come into contact with feces contaminated with the virus. The virus can be carried on inanimate objects and the hand and skin of a person handling an infected dog as well.

Once infected, the virus attacks the lining of the intestinal tract of the infected dog, causing the lining to slough or die off. As the lining of the intestinal tract dies, bacteria which normally populate the intestinal tract and toxins from within the intestinal tract begin to invade the blood stream, causing toxemia and bacteremia (the buildup of toxins and bacteria within the blood stream, respectively). Toxemia and bacteremia further complicate the course of the disease.

Symptoms of “Parvo” in Puppies and in Dogs

Young dogs and puppies usually develop the most serious disease because of lack of immunity to the virus. Mature dogs may still be susceptible to parvovirus but have often built up enough immunity to allow the dog to fight the virus more effectively.

The symptoms that occur in a dog or a puppy with parvovirus are:

  • diarrhea, with or without blood in the feces
  • vomiting
  • fever
  • lack of appetite
  • depression
  • abdominal pain
  • dehydration

In many cases, bloody diarrhea may appear to be primarily frank blood passing from the rectum.

The fluid loss which results from the vomiting and diarrhea caused by the parvovirus results in profound dehydration. To complicate matters further, dogs infected with parvovirus are usually not able to hold down food or water, making it impossible for them to replace their fluid loss by themselves.

Dehydration with parvovirus, if left untreated, will eventually result in the death of the infected dog.

Treatment of Parvovirus in Infected Dogs and Puppies

The primary objective of treatment is to battle the resulting dehydration. This is done through fluid therapy, replacing the fluid loss and attempting to maintain the hydration status. In some cases, if dehydration can be controlled, the infected dog may be able to eventually mount an immune response and fight off the infection. However, it is not always possible to maintain the hydration status and correct the other complications that occur with parvovirus. Parvovirus is fatal in a large percentage of infected dogs.

Besides fluid therapy, other treatments are generally necessary as well. Antibiotics are often used to prevent secondary bacterial infections. Medications may also be necessary to try to control vomiting and control pain. It is usually necessary to administer these medications by injection as the infected dog is often not able to hold down oral medications, at least in the initial stages of the infection.

Preventing Canine Parvovirus Infections in Dogs

Vaccinations against parvovirus are quite effective in preventing infection with the disease. Parvovirus vaccines are considered “core” vaccines and are recommended for all dogs.

Vaccination against parvovirus should begin when a puppy is between 6 and 8 weeks of age. The puppy should receive a booster vaccine every 3-4 weeks until he has reached an age of 14 to 16 weeks of age. The booster vaccine should be repeated in one year and every one to three years after that, depending on your veterinarian’s vaccination protocol.

It should be remembered that some puppies will remain susceptible to infection with parvovirus up until the last “puppy booster” at 14 to 16 weeks of age. So, care should be taken with young puppies to protect them from exposure to the canine parvovirus. Though socialization is important for young puppies, it is also important that a puppy’s playmates be healthy and free of disease, up-to-date on vaccinations and free of parasites.

About Lorie Huston, DVM

Lorie Huston, DVM has written 88 posts in this blog.

Lorie Huston is a veterinarian with 20+ years of experience with dogs and cats. She is also a talented free-lance author and blogger and has contributed to numerous publications, including Pet Sitter's WORLD, FIDOFriendly, Dancing Dog Blog, Dawg Business and many others. Lorie is the featured pet care writer at, a contributing writer in Dog and Cat Diseases and Conditions at and the National Pet Health Examiner at In addition, she is a host of the popular podcast/review site, Animal Cafe.



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