Parvovirus and Dogs

Deadly Virus Can Spread Quickly

Parvovirus cell

Jennifer Hawkins, DVM

Healthy puppies are usually a blur of activity, happily playing, chewing and barking. So, if your puppy is just laying with her head on her paws, not eating at all but occasionally vomiting and pooping quite a bit—a watery, bloody diarrhea with a foul odor, chances are she has contracted a deadly virus known as canine parvovirus.

What is Parvovirus?

Canine Parvovirus, or Parvo, is caused by a virus designated as CPV-2 which affects dogs and wild canids such as wolves, coyotes and foxes. A varient of the CPV-2 virus is said to infect cats in Asia. Dogs with an immature or poor immune status and dogs that have not been vaccinated for Parvo are extremely susceptible. This virus attacks rapidly reproducing cells, especially white blood cells and cells of the gastrointestinal tract.

Early destruction of white blood cells by the virus reduces the pet's ability to fight off the disease; the virus spreads rapidly through the blood to the intestines, where it destroys cells and causes vomiting and diarrhea.

How Do Dogs Acquire Parvo?

Parvo is a hearty virus that can live in the environment for months. Anywhere that a dog shedding Parvo has recently been is a place where the virus is waiting for a new host. Puppies are the primary victim as they often have not been completely vaccinated and thus are very susceptible.

As all dogs explore the environment with their noses and mouths, they easily pick up the virus from infected fecal matter. Within 3 to 7 days, the puppy starts showing symptoms of Parvo.

Is Parvo Contagious to Other Animals?

Parvo is a disease of the canid family in North America. Other mammals have their own species-specific parvovirus; canine parvovirus primarily affects dogs and other members of the canid family including wolves, coyotes and foxes. CPV-2 is not contagious to humans but is highly contagious to other dogs through the fecal oral route.

Symptoms of Parvo


When the Trueblood family of Irvine, Calif., adopted a miniature Schnauzer puppy they named CJ, he was a seemingly healthy, rambunctious puppy, happily chasing the children throughout the home. Two days later, CJ began throwing up.

Stacey Trueblood took note of the vomit, thinking it was due to an upset stomach.

“I thought maybe CJ had eaten something off the floor that one of the kids had dropped,” explains Stacey. “I made a mental note to keep an eye on him. By the next morning, he began having diarrhea and I knew immediately something was wrong.”

Dogs affected with Parvo can become lethargic, begin vomiting and have a poor appetite and stinky diarrhea. Since the cells of a dog’s gastrointestinal tract are affected, these cells don't absorb nutrients as they should. In fact, these dying cells are sloughed off and pass into the feces, accounting for the horrible smelling bloody diarrhea.

Some dogs may only show one of these signs or, like CJ, a couple symptoms, while others will have all them.

How is Parvo Diagnosed?

A simple ELISA test is all that's needed to diagnose Parvo. You know how a pregnancy test has one line for a negative test result and two lines for a positive? The ELISA test works very much the same way. A small swab of fecal matter is tested and within 10 minutes, the results are known.

These test results are typically quite accurate. In rare cases, a recently administered Parvo vaccine may cause a false positive test result. But, as we say in the veterinary business, if it looks like Parvo and smells (pheew!) like Parvo, then it's Parvo.

Once Parvo has been confirmed, other tests often performed are a blood panel and urinalysis. These tests are part of the minimum data base we like to have so that we know the white blood cell count, electrolytes, blood sugar and overall organ function of the patient. This can help determine our prognosis and course of treatment.

Make no mistake, canine parvovirus is a deadly virus and the sooner treatment is started, the better are the chances for survival.

When the Truebloods took CJ to their family veterinarian, three days after adopting him, they were advised that their puppy was showing signs of Parvo and that a couple of tests would be conducted, including a blood panel and a fecal test. Their vet wanted to find out if CJ had Parvo or internal parasites like coccidia, giardia and roundworms, which can often mimic the symptoms of Parvo.

It turned out that CJ had coccidia and Parvo; due to the aggressive nature of the virus, it was critical that a course of treatment was set quickly in place. Would CJ pull through?

How is Parvo Treated?

Make no mistake, canine parvovirus is a deadly virus and the sooner treatment is started, the better are the chances for survival.

CJ and the Trueblood family

If an affected puppy continues to be feed regular meals, it could contribute to dehydration via fluid losses in vomit and diarrhea. Therefore, we are very limited in supporting an affected dog through her disease process. Ideally, the patient should be hospitalized and given intravenous fluids, sometimes with dextrose (sugar) added to help keep her hydrated while her immune system fights off her infection.

We also want to help prevent the vomiting and diarrhea so we administer antiemetic agents and medications that prevent diarrhea. Parvo infected dogs are also typically given antibiotics. The antibiotics will do nothing for the parvovirus but, remember, the white blood cells are low and they are important in fighting infection.

With those unhealthy gastrointestinal cells and minimal white blood cells to fight off infection, bacteria from the gut can get into the blood stream and cause systemic infection, or sepsis. If blood tests show the puppy has low blood protein due to losses through her stomach, she may also need a plasma transfusion to prevent complications from low blood protein.

CJ was kept overnight with the Trueblood’s veterinarian, where he received fluids and antibiotics through an IV.

“Our vet said we had a 70 percent chance to save him since the virus was caught early enough,” recalls Stacey. “Then we brought him home and within 24 hours he started taking a turn for the worse: He became lethargic and his gums had turned gray (showing signs of dehydration). We immediately took him back to the vet where he stayed for four days.”

CJ continued to receive fluids and antibiotics through an IV until he began to show signs of recovery. When he went home with his family, he was fed one tablespoon of prescribed pet food every hour and given enough water to keep him hydrated. The Truebloods were instructed to watch for any signs of a relapse, including wet stool.

Can Dogs Make a Full Recovery from Parvo?

Aggressive hospital care, IV fluids and medicine to treat the symptoms of Parvo and prevent secondary bacterial infection are usually needed to support a puppy while her body fights off the virus.

Many dogs respond well to this support and make a full recovery. In some cases extreme complications such as endotoxemia or a systemic inflammatory response can worsen the prognosis.

It was a slow recovery for CJ, but within a few weeks he starting acting like a puppy again and got a clean bill of health from his veterinarian.

“I think our vet played a huge part in the outcome,” says Stacey. “He was honest with us about CJ’s chances and worked with us to make the right decision for our dog—for our family. We were going to do what we could to save him. The experience taught us about life and death; it also taught us what kind of questions to ask before adopting a puppy from a breeder and environmentally what to be aware of when it comes to bringing puppies home.”

How Can I Prevent My Dog From Getting Parvo?

While you want to socialize your puppy, you also need to be aware of potential risk of infection until she has completed her vaccination series.

Until your puppy is completely vaccinated, avoid areas that are frequented by high numbers of dogs such as dog parks and pet stores. Also, be sure to follow your veterinarian's vaccine recommendations. If you have had a dog with Parvo recently, don't introduce another puppy for at least 6 months to decrease the risk of the new dog acquiring Parvo from the environment.

If you notice symptoms consistent with Parvo, don't delay: Visit your veterinarian right away to ensure the best prognosis for your beloved pooch!

Return to the VPI Pet HealthZone

Dr. Jennifer Hawkins and Ernie

Dr. Hawkins received her veterinary degree from the University of California, Davis and practices in Orange County, Calif., where she also works at local animal shelters. In addition, she is an advisory faculty member for aspiring veterinary technologists at California State Polytechnic University Pomona. Dr. Hawkins is an active member of the Southern California Veterinary Medical Association where she serves as president on the Board of Trustees.

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