What Is Parvo?

What is Parvo

Canine Parvovirus Type 2 is one of the most severe illnesses that a dog can contract. It is also any fur parent’s worst fear. A seemingly healthy dog can go from playing at the park to fatally ill in a matter of a few short days. Parvo is a highly contagious viral disease that causes extreme sickness by attacking the gastrointestinal tract or heart muscles of a dog. When left untreated, Parvo typically leads to death.

The good news? Parvo is preventable. There has been extensive research conducted on the fatal disease, so keep reading to find out how the virus impacts a dog’s body.

How Do Dogs Get Parvo?

Canine Parvovirus

Facts About The Virus

Canine Parvovirus first emerged in 1978 and has since been found in Asia, Australia, Europe, the Americas, and New Zealand. Since its discovery in the 1970s, pet health experts have studied it thoroughly. Stool specimens and animal tissues have been observed. Parvo has been widely recognized as a pathogen that impacts dogs throughout the world with a high mortality rate.

Here’s a quick timeline of the medical history of the virus:

  • The 1970s – Discovery
  • 1978 – Two scientists, Dr. Leland Carmichael and Dr. Max Appel, first isolated the virus at The Baker Institute for Animal Health. 
  • 1979 – the scientists had developed the first vaccine for Parvo.

The occurrence of the disease is higher in animal shelters, pet stores, and breeding kennels, where many potential hosts are living in small, confined areas. It is much less common for a dog to be diagnosed if they mainly stay isolated from other dogs in the home or the yard. 

All dog breeds and ages are susceptible to Parvo. However, mutts and crossbreeds are at less risk than purebreds such as German Shepherds or Rottweilers. Scientists are not entirely sure why purebreds are at a higher risk of contracting the disease. They suspect it is due to the breeding of dogs with similar genetics. 

Intestinal VS Cardiac Parvo

Intestinal Parvo

Intestinal Parvovirus presents itself as intestinal inflammation with symptoms of vomiting and diarrhea. The intestinal form of the virus is most common among dogs. It affects the body’s ability to absorb nutrients, which leads to dehydration and fatigue from lack of protein and fluid absorption.

Cardiac Parvo

Cardiac Parvo is characterized by myocarditis (heart inflammation), leading up to heart failure.  The cardiac form of Parvo is less common, however it is more severe, attacking the muscles of the heart. Most cases of the cardiac form occur in puppies between the ages of six weeks and six months old.  (PetMD)



Canine Parvovirus is primarily spread through dog-to-dog contact, either from exposure to another infected animal’s feces or from bodily fluids of an infected dog. An infected dog can shed the virus in their feces starting around three to four days after infection, and up to fourteen days post-infection.

The virus can also live on a dog’s coat and can serve as a means of transmission. Dogs can also get the virus through the environment. 

If an area is not cleaned or sterilized, shaded areas will harbor the disease for a long time. The virus has a lower life expectancy in places that are almost always in direct sunlight. Parvo also has a shorter life expectancy indoors at room temperature. However, you should always thoroughly clean your home with a diluted bleach solution to ensure the disease has been eradicated.

Incubation Period

The incubation period refers to the period between infection and the presentation of Parvo symptoms. Each incubation period depends on the following factors:

  • The severity of the illness
  • Age of the animal
  • Strength of the immune system

In Canine Parvovirus, the typical incubation period is about 3-7 days.

Physiological Changes

After the virus enters the body, it begins to replicate in the lymph nodes. A large amount of the pathogen enters the bloodstream. In the following 3-4 days, the virus travels to other organs where it destroys young cells of the immune system and lowers the body’s defense against pathogens by reducing the white blood cell count. After the incubation period, you may start to notice severe diarrhea, lethargy, vomiting, weight loss, and a lack of appetite in your dog.

Intestinal Parvo

In the intestines, there are small, finger-like structures called villi. Villi significantly increases the surface area available for the absorption of nutrients. The villi cells typically have a short lifespan, and therefore are constantly replaced by new cells.

Parvo targets the site in which these new cells are replaced. After Parvo attacks these sites, the villi can no longer absorb nutrients and fluids, resulting in diarrhea. Additionally, the barrier that divides the digestive bacteria from the bloodstream deteriorates, and diarrhea becomes bloody. Bacteria can now enter the body, causing widespread infection (Nandi and Kumar, 2010).


Parvo causes intestinal bacteria to travel into the bloodstream, which then has the potential to cause sepsis.

According to Veterinarian Dr. Patrick Mahaney VMD, CVA, CVJ (2018), “As Parvo replicates in the lymph nodes, the lymphatic vessels permit it to reach the bone marrow and the digestive tract. Inside the bone marrow, Parvo negatively impacts the production of new white blood cells. When white blood cell production decreases, it increases the potential for infection with bacteria, fungi, parasites, and viruses. In the digestive tract, Parvo damages the inner-most parts of the intestines.

After these physiological changes have occurred, Parvo typically takes the animal in one of two ways: diarrhea and vomiting lead to fluid loss and dehydration, resulting in death. Or, the loss of the intestinal barrier creates a pathway for bacteria to infect the entire body, leading to the same morbid outcome.

Cardiac Parvo

There has not been as much research conducted on the cardiac form of Parvovirus, as it is not as common as the intestinal form of the disease. However, researchers have found that cardiac Parvo causes sudden heart failure, as the disease targets the muscles in the heart. Most puppies will die due to cardiogenic shock, where the heart suddenly cannot pump enough blood to meet the body’s needs.

Respiratory complications are common, and the virus will typically cause rapid breathing and shortness of breath. Some signs to look for include difficulty breathing, a puppy that stops nursing, lethargy, and a dog’s abdomen may also swell due to an enlarged liver.

Survival Rate

The survival rate for Canine Parvovirus is about 85-90%. The rate is highly affected by the medical care and attention provided. Despite these statistics, the media has portrayed this disease as a definite death sentence. However, despite what the media may say about Parvo, your dog has a very high chance of surviving and beating the disease if you take the proper steps of care.


What does Parvo mean?

Parvo stands for Canine Parvovirus, which is a highly contagious and severe viral disease that affects dogs. The virus occurs in two forms: intestinal and cardiac.

What does Parvo look like?

A dog infected with Parvo may exhibit diarrhea, vomiting, lethargy, and a lack of appetite within 3-10 days of exposure. For more detailed information, check out the Signs and Symptoms page.

At what age will my dog get Parvo?

Young and unvaccinated dogs are most at risk of getting Parvo. It takes time for the vaccination series to become effective, thus making young, uninoculated dogs more susceptible to Parvo.

However, even older dogs have fallen victim to this disease. 

Which animals carry Parvo?

There are different strains of Parvovirus present in the world. Among them are:

  • Canine Parvovirus 
  • Parvovirus B19 (affects humans)
  • Feline Parvovirus (Feline Distemper or Feline Panleukopenia)


Which dogs are more likely to catch Parvo?

Any dog can catch Parvovirus. However, puppies and unvaccinated dogs are more susceptible. Some breeds are more at risk than others, including Rottweilers, Doberman Pinschers, Labrador Retrievers, German Shepherds, American Staffordshire Spaniels, and English Springer Spaniels.


Where can you buy a Parvo test kit?

Parvo test kits are not always reliable because they can provide false results. The best course of action is to visit your veterinarian to get an accurate test for Parvo.

Why do puppies get Parvo?

Puppies can get Parvo from their mother or their environment. They are at high risk for catching Parvo because they are unvaccinated and vulnerable to the disease until they have had the complete round of shots. 

What will kill Parvo besides bleach?

We suggest you try KennelSol, used by animal shelters as well as pet owners alike, or ProVetLogic Pet Spray and Wipe Disinfectant. Both cleaning products are highly recommended on Amazon. Check out our Prevention page for more home cleaning tips and information about how to disinfect your yard.