What Is Parvovirus?

Written by Alicia Racelis, PhD, WebMD Editorial Contributor
Medically Reviewed by Amy Flowers, DVM on November 29, 2025
6 min read

Canine parvovirus is a virus that only infects dogs, coyotes, wolves, foxes, raccoons, and skunks. The virus can easily spread through an infected animal's poop, especially in younger dogs. So when you get a new puppy, although it's tempting to show them off, consider not taking them out right away.

Before you take you dog out, make sure your dog is completely vaccinated against the canine parvovirus, also called parvo. The virus was first noticed in 1976 in Europe.

Parvo infects your dog's small intestines and can make absorbing nutrients impossible. But in young puppies, it can also affect the heart and become deadly. No matter what age your dog is, they're at risk without the vaccine.

Do some dogs have a higher parvo risk?

Canine parvovirus usually infects quickly growing cells in your dog's intestines or bone marrow. But some dogs can get parvo easier than others. Puppies between 6 weeks and 6 months old are most vulnerable to parvo, as are certain dog breeds such as:

  • Doberman Pinschers
  • English Spaniels
  • German Shepherds
  • Pit bull-type dogs
  • Rottweilers

Learn more about canine parvovirus, the viral stages, the latest treatments, and the ways to prevent infection in your dog.

Most often, parvo spreads through an infected dog's poop (feces). An infected dog's poop can contain parvovirus for four to five days, often before it shows symptoms. Dogs that have parvo generally don't have symptoms for three to seven days.

During this time, they can infect other dogs with their poop. And even if your dog gets parvo treatment, it can still infect other dogs up to 10 days after it has recovered from the parvovirus infection.

Where does parvovirus live?

Parvo can survive indoors for up to a month. But outdoors, the virus can live in soil for as long as a year. That means if a dog infected with parvo has been to a public space in the past year, your puppy could contract the disease from there. 

How can I protect my puppy from parvo?

Puppy owners can protect their dogs by not taking them out in public until they get all four parvo vaccinations. The four shots help build up your puppy's immunity. 

Your vet may suggest starting with the first parvo vaccine at 6 weeks, followed by a vaccination every three weeks until your puppy is 16 weeks old.

Some of the first symptoms you may notice for parvovirus is usually unexpected tiredness or lethargy.

Next, your dog may lose its appetite as the virus attacks their small intestine lining.

Shortly after, it will spike a sudden fever and begin to have diarrhea and vomiting.

While these symptoms are common to parvo, they can also be the result of other conditions. If your dog has bloody diarrhea, contact your vet right away to get your dog tested and treated properly.

The parvovirus enters your dog's body usually through infected poop. Inside your dog, the virus infects cells that often grow quickly, such as the tonsils and lymph nodes inside your dog's throat.

Enters the white blood cells

Once parvo is in your dog's lymph nodes, the virus gets inside a type of white blood cell called lymphocytes. After one or two days, the virus makes many copies of itself.

The virus also kills many lymphocytes, which weakens your dog's immune system. Parvovirus can then ride on lymphocytes in the bloodstream to reach other organs. 

Enters the organs

The bone marrow, the heart, and the cells that line the small intestine are affected the most. Without this protective lining in their small intestine, your dog can't absorb nutrients.

In puppies, the heart cells can also die off, causing inflammation and irregular heart rhythms. 

Weakens the body

The virus weakens your dog's body and immune system. The older cells can't be replaced because the parvovirus stops the growth of new ones. Also, your dog can't absorb nutrients and can get diarrhea and nausea. 

Your dog can lose fluids (get dehydrated) and get other infections, too. This dehydration and shock can become life-threatening if untreated.

The best treatment is prevention with vaccination. But if your dog gets parvo, a newer treatment called canine parvovirus monoclonal antibody (CPMA) can help.

CPMA uses man-made antibodies, which can block the virus before it takes hold in your dog's body. The one-dose treatment works for dogs 8 weeks and older.

Will my dog need hospital treatment?

In most cases, dogs with parvo will need to spend time at a veterinary hospital. Your vet can monitor and ease your dog's symptoms using supportive care. These treatments give your dog's immune system the best chance to fight off the virus. Supportive care can include:

  • Intravenous (IV) fluids to replace those lost to diarrhea and vomiting
  • Blood transfusions to help keep blood cell counts normal
  • Anti-nausea and anti-diarrheal medications to help dogs retain fluids
  • Antibiotics if the dog has come down with another (secondary) infection

Adult dogs usually recover from parvo if they get the right treatment. Healthy and strong puppies may survive if treated early.

First, you can get the combination vaccine for your dog that protects it from canine:

Once your puppy turns 6 weeks old, it will get the combo shot:

  • Every three to four weeks until it's at least 16 weeks old
  • A booster shot one year later
  • A booster shot every three years

Widespread vaccination against the virus is why parvo is an occasional risk than a constant one. And getting the full series of shots, starting at 6 weeks, helps your puppy build its immunity.

Isolate a sick puppy

Second, if your puppy is too young for the vaccine, you believe your dog has been exposed to parvo, or your dog has symptoms:

  • Keep your dog away from other dogs.
  • Stay away from public places.
  • Call your vet, and take your puppy in right away.

The simplest way to keep your dog from getting sick is to prevent it from getting parvovirus. So, keep your puppy safe until it's old enough for vaccinations.

Yes, they can, if they aren't vaccinated. Parvovirus can infect dogs of any age if they haven't received the vaccine for parvo. That's because their immune system takes time to learn how to fight off the virus.

With treatment, about 68%-92% of dogs can survive the viral infection. To keep your dog from getting infected with parvo, talk to your vet about the parvo vaccine.

One of the biggest and deadliest dangers for puppies and young dogs is the canine parvovirus. The virus only infects dogs, and it usually happens through infected poop. You should keep your puppies safe and isolate them until they're fully vaccinated at 16 weeks. But if you think your dog was exposed, tell your vet right away. They can give your dog the best treatment.

Can I touch my dog if it has parvo?

You are not at risk for parvo and can touch your dog if you're not around other unvaccinated dogs. It's best to clean and properly disinfect everything for up to two weeks after your dog's recovery, though.

How many days is a dog contagious with parvo?

An infected dog is contagious (can infect other dogs) with parvovirus before it shows symptoms and up to two weeks after it gets better.

What happens if a dog with parvo licks you?

You can't get parvovirus from a dog licking you. That's because the virus only infects dogs. But if your dog has licked some poop infected with the virus, try to prevent the spread to unvaccinated dogs by keeping your dog isolated. Wash your hands with a cleaner that can kill parvovirus, and try to use:

  • Diluted household bleach (dilute one part bleach with 30 parts of water)
  • A commercial cleaner labeled to kill or inactivate parvovirus

At what age is a dog safe from parvo?

Parvovirus can infect an unvaccinated dog of any age. But dogs can't get parvovirus if they:

  • Are protected 
  • Have completed two vaccines, three weeks apart, and the full vaccine series
  • Get a booster a year after completing the series and then every three years