What Is Parvo?
Canine Parvovirus Type 2 is one of the most severe illnesses that a dog can contract, and is therefore any dog owner’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 a dog’s gastrointestinal tract or heart muscles, and typically leads to mortality if left untreated. The good news? Parvo is preventable and 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 Does Parvo Get Passed?
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 1970’s, the disease was studied in stool specimens and animal tissues, and has been widely recognized as a pathogen that impacts dogs throughout the world with a high mortality rate. Two scientists, Dr. Leland Carmichael and Dr. Max Appel, first isolated the virus in 1978 at The Baker Institute for Animal Health. By 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 there are many potential hosts living in small, confined areas. It is much less common for a dog to be diagnosed if he or she mainly stays isolated from other dogs in the home or in the yard. All breeds and ages of dogs 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 as to why purebreds are at a higher risk of contracting the disease, but they suspect it is largely due to the breeding of dogs with similar genetics. While breeding dogs ensures certain traits are continued such as a calm temperament or a physical trait, breeding also passes on many diseases and genetic problems.
Intestinal VS Cardiac Parvo
Intestinal Parvovirus is characterized by intestinal inflammation with symptoms of vomiting and diarrhea. The intestinal form is most common among dogs, affecting the body’s ability to absorb nutrients which leads to dehydration and fatigue from lack of protein and fluid absorption.
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 his or her 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.
Parvovirus can also be transmitted through the environment. The virus can survive in the environment for several months and sometimes several years if the protective conditions are right. If no cleaning or sterilizing steps are taken, shaded areas will harbor the disease for the longest amount of time, whereas the virus has a lower life expectancy in areas 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, inside and out, with a diluted bleach solution to ensure the disease has been eradicated.
For more information on cleaning and sterilizing your home, visit our Prevention page for a list of Parvo cleaning products and information about sterilizing after an infected dog.
The incubation period is the typical period of time that it takes from a dog’s exposure to a virus, to the time that the symptoms are physically noticeable. Each incubation period is different depending on the severity of the illness, the age of an animal, and the strength of a dog’s immune system. In Canine Parvovirus, the typically incubation period is about 3-7 days.
After the virus enters the body, it begins to replicate in the lymph nodes, and a large amount of the pathogen is released into 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 lowering 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.
In the intestines, there are normally little finger-like structures called “villi”, which significantly increase the surface area available for the absorption of nutrients. The cells of the villi typically have a short lifespan, and therefore are constantly replaced by new cells. Parvo targets the site in which these new cells are being replaced, and after Parvo has made its presence, 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 the diarrhea becomes bloody. Bacteria can now enter the body, causing widespread infection (Nandi and Kumar, 2010).
Parvo causes bacteria that normally thrives in the intestines to travel into the blood, which then has the potential to cause sepsis. According to Veterinarian Dr. Patrick Mahaney VMD, CVA, CVJ, “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” (Mahaney, 2018).
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.
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.
The survival rate for Canine Parvovirus is about 85-90%, and the rate is highly affected by the treatment that is provided and the steps that are taken to provide medical care and attention. 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 actually has a very high chance of surviving and beating the disease if you take the proper steps of care.
Top 5 FAQ
Parvo is short for Canine Parvovirus, a highly contagious and severe viral disease that impacts dogs. The virus can affect either the intestines or the heart, depending on the form.
Parvo symptoms most commonly begin to show 3-10 days after exposure. Typical signs to look for include diarrhea, vomiting, lethargy, and a lack of appetite. For more detailed information, check out the Signs and Symptoms page.
Dogs can get Parvo at any age, but puppies are most at risk. It takes time for the full vaccination series to become effective, and unvaccinated dogs are more susceptible to the virus.
There are many different strains of Parvovirus that impact different animals. Canine Parvovirus impacts dogs, humans get Parvovirus B19, and cats can contract Feline Parvovirus (Feline Distemper or Feline Panleukopenia).
Any dog can catch Parvovirus, however puppies and unvaccinated dogs are more susceptible. There are also some breeds that are more at risk than others, including Rottweilers, Doberman Pinschers, Labrador Retrievers, German Sheperds, American Staffordshire Spaniels, and English Springer Spaniels.
Other Frequently Asked Questions
You should always visit your veterinarian to get an accurate test for Parvo. Parvo tests can often provide false negatives and even false positives, so it is important to have a professional perform a test and determine a diagnosis based on your dog’s symptoms.
Puppies are at a high risk for catching Parvo because they are unvaccinated and vulnerable to the disease until they have had the full round of shots. They can also be infected by their mother with the virus while they are still in utero.