Canine Parvovirus: Vaccination is Key

By: Mary Newell Sanders, DVM

TVMA Member
Bellville, TX

Published April 2014

What is parvovirus?

Canine parvovirus (parvo) is a highly contagious virus that affects dogs. There are two forms of the virus—intestinal and cardiac. The intestinal form is more common and is characterized by profuse vomiting, bloody diarrhea and life-threatening dehydration. In the less common cardiac form, the virus attacks the muscles of the heart, often leading to death. Both forms can affect the bone marrow, resulting in severe drops in white-blood-cell counts and subsequent susceptibility to secondary bacterial infection. The majority of cases are seen in puppies that are between six weeks and six months old, but any unvaccinated dog is susceptible to the disease.

How can a dog become infected with parvo?

A dog becomes infected with parvo either by direct contact with an infected dog or by ingesting the virus through fecal-oral contact. A person can unknowingly bring the virus into a dog’s environment by tracking infected feces on the bottom of shoes. Diseases or drug therapies that suppress the normal response of the immune system may also increase the likelihood of infection.

Parvo is very common in urban area such as dog parks, shelters, suburban backyards, breeder properties, boarding areas and veterinary practices. However, it is very hard to predict where an unvaccinated or under-vaccinated animal will contract the virus.

Breeders will often verbally assure the person adopting a new puppy that it has been vaccinated. However, always transport a newly adopted puppy to a veterinarian for an exam, because they are at high risk for infectious disease.

What are the signs of parvo?

In a dog infected with parvo, most owners first notice that their dog is lethargic (sluggish), doesn’t want to eat and is losing weight. The dog may act as if its abdomen (belly) is painful. Clinical signs then progress to profuse vomiting and/or bloody diarrhea, which quickly lead to life-threatening dehydration. The dehydration is often more deadly than the virus itself. Some dogs with parvo will run a fever, but many times, due to the severity of the virus, dogs will be hypothermic (have a low body temperature).

If there is any suspicion that your pet has contracted parvo, transport it to a veterinarian immediately. This is a life-threatening illness that can cause death within 24 hours.

How does a veterinarian diagnose parvo?

In order to diagnose parvo, a veterinarian will perform a physical exam and take a fecal sample. Most veterinary clinics have an in-house test they can run that indicates almost immediately whether or not a dog has parvo. A veterinarian may also recommend bloodwork, urinalysis, abdominal x-rays and/or abdominal ultrasound to rule out diseases with similar signs.

What is the treatment for parvo?

Treatment for parvovirus can be difficult and costly. Because parvo is a virus, there is not a drug a veterinarian can give to cure the infection. Treatment is focused on alleviating the symptoms of parvo, like dehydration, until the virus runs its course. An infected dog needs fluids to replace those lost by vomiting and diarrhea, but if it is vomiting, nothing can be given orally. The best way to treat a dog infected with parvo is to hospitalize it for intravenous fluid and nutritional support and injectable medications. A veterinarian may give anti-emeticsOf or pertaining to a substance that is useful in the suppression of nausea or vomiting. to help curb nausea and vomiting or antibiotics for secondary bacterial infections. A veterinarian can also monitor a dog’s protein and electrolyteA liquid or gel that contains ions and can be decomposed by electrolysis, levels, as well as other vital signs, and regulate them as needed.

The chance for survival of infected dogs varies greatly. Many dogs do recover from parvo with proper treatment, but death may sometimes result from severe dehydration, secondary bacterial infection, bacterial toxins in the bloodstream (septicemiaBlood poisoning, esp. that caused by bacteria or their toxins.) or intestinal hemorrhageAn escape of blood from a ruptured blood vessel, esp. when profuse. (bleeding). Once a dog does recover, it will still be shedding the virus in its feces for at least two weeks, if not longer, making it a contagion risk to other dogs. Therefore, even after a dog has recovered, it will need to be isolated for some time. Parvovirus is very resistant to many disinfectants and can survive in an environment for more than a year. Everything a recovered dog uses (bowls, kennels, toys, etc.) must be thoroughly disinfected. A dilute bleach solution (a half-cup of bleach to one gallon of water) is effective for killing the virus.

How can a pet owner protect their pet from parvo?

Parvovirus is easily preventable with proper vaccination. Puppies require multiple sets of vaccinations in order to be fully protected from diseases like parvo; a single vaccination does not ensure immunity. Vaccines should start at about six weeks of age, so do not delay taking a new puppy in to see a veterinarian. Vaccines may have to be administered every three to four weeks until it is 16 weeks old. Older dogs with an unknown or improper vaccine history should be vaccinated as well.

Canine parvovirus is a highly contagious, sometimes deadly disease that can affect any dog or puppy. Proper vaccination is key to avoiding infection, so talk to your veterinarian to make sure your dog’s vaccines are up to date.


Dr. Mary Newell Sanders practices at Marek Veterinary Clinics in Bellville and Sealy, Texas.

One Response

  1. Do you have a map showing parvo rates in a variety of Texas areas. We are thinking of moving there, but are concerned about dog breeding conditions.

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