Parvovirus Kills. Is Your Dog Protected?

With all the discussion of Parvo in the Pembroke and the Ottawa Valley, we decided to sit down with Dr. Shari Sims, DVM and have her answer some important questions about the virus. Dr. Sims has been practicing veterinary medicine at PAH and our Wellness Clinics; Deep River Animal Services and Mohns Avenue Veterinary Services, since 2000, and is very familiar with the diagnosis and treatment of Canine Parvovirus.

What is Parvo?

Canine Parvovirus (CPV), commonly referred to as Parvo, is highly contagious virus that affects dogs. It is a particularly deadly disease in young puppies with up to an 80% fatality rate.


How do dogs and puppies contract Parvo?

Parvo can be found in almost any environment. It is transmitted when a susceptible dog comes in contact with the virus. This includes contact with the feces of an infected dog, or objects that contain the virus (shoes, clothes, bedding, bowls, grass, carpets, floors, etc). Parvo is a very hardy virus in the environment and is resistant to extreme heat, freezing, detergents and many disinfectants. Dogs that are exposed to Parvovirus start to show signs of illness 3-10 days later. Infected dogs start to shed the virus a few days before clinical signs appear, and continue to shed the virus for approximately 10 days.


Dr. Shari Sims, Pembroke Animal Hospital

Dr. Shari Sims, Pembroke Animal Hospital

What dogs or puppies can get Parvo? How can my dog or puppy be protected from Parvovirus?

Any unvaccinated puppy or unvaccinated dog is at risk of getting Parvo. For best protection, puppies need to complete a full series (3 Parvo vaccinations at 8, 12 and 16 weeks of age) and adult dogs need to have Parvovirus booster vaccines every 1-3 years, as determined by your veterinarian. If your puppy or adult dog is not fully vaccinated, they are risk of contracting Parvo.  If your puppy or dog is not up to date on vaccines, do not take your pet into any public areas, and call your Veterinarian to make an appointment for vaccination. Parvovirus is considered a core vaccine for all puppies and adult dogs.


What are the signs of Parvo?

  • Lethargy
  • Vomiting, often with blood
  • Severe bloody diarrhea
  • Loss of appetite
  • Dehydration
  • Fever

How is Parvo diagnosed?

The clinical signs of Parvo infection can appear similar to many other diseases that cause vomiting and diarrhea. The confirmation of Parvo infection is often achieved by isolating virus antigen in the stool.

There is a simple in-clinic test for Parvo that will screen for this disease. Occasionally, a dog will have Parvovirus but test negative for virus in the stool. Fortunately, this is an uncommon occurrence. A tentative diagnosis is often based on the presence of a reduced white blood cell count (leukopenia) and clinical signs. The absence of leukopenia does not mean that the dog does not have Parvo infection since some dogs that become clinically ill may not have a low white blood cell count.

Your Veterinarian may want to do additional tests (fecal flotation, bloodwork and abdominal radiographs) to confirm that your dog does not have any other illness or condition that may complicate treatment for Parvo infection.

How does infection with CPV make a dog sick?

Parvo first infects the tonsils and lymph nodes in the mouth, and then travels via the lymphocytes (white blood cells) to the bloodstream. Once in the blood stream, the virus attacks rapidly dividing cells, including the cells that line the intestinal tract, bone marrow and the heart.

The virus causes destruction of the epithelial cells of the small intestine, which is the lining that helps to absorb nutrients and provides a barrier against fluid loss and bacterial invasion from the gut into the body. Severe diarrhea and nausea are the initial result, but eventually the intestinal surface can become so damaged that it begins to break down, and the bacteria that are normally contained in the gut penetrate the intestine walls and enter the bloodstream. To make matters worse, the body’s immune system is already weakened, as its ability to produce new white blood cells to fight infection has been hampered by the invasion of Parvo into the bone marrow. Parvo is not always fatal, but when it does kill, death is as a result of either dehydration and/or shock, along with the effects of septic toxins produced by the intestinal bacteria roaming throughout the bloodstream.

Can Parvo be treated?

There is no treatment to kill the virus once it infects the dog. However, the virus does not directly cause death but it causes destruction of the intestinal tract, and some blood cells. The intestinal damage results in severe dehydration (water loss), electrolyte imbalances (sodium and potassium), and infection in the bloodstream (septicemia).

The first step in treatment is to correct dehydration and electrolyte imbalances. This requires the administration of intravenous fluids. Antibiotics are given to prevent or control septicemia. Medications to prevent vomiting and protect the lining of the stomach are used to inhibit the diarrhea and vomiting that perpetuate the problem.

What is the survival rate?

Most dogs with Parvo infection recover if aggressive treatment is used and if therapy is begun before severe septicemia and dehydration occur. So, if your dog appears ill, seek veterinary care as soon as possible. In most cases, puppies that have not improved by the third or fourth day of treatment have a poor prognosis for recovery.

How can the virus be killed in the environment?

The stability of Parvo in the environment makes it important to properly disinfect contaminated areas. A solution of 1/2 cup of chlorine bleach in one gallon of water (133 ml in 4 liters of water) will disinfect food and water bowls and other contaminated items. It’s important that chlorine bleach be used because most disinfectants, even those claiming to be effective against viruses, will not kill the canine parvovirus.

Can other members of the family get Parvo?

Currently, there is no evidence that Canine Parvovirus (CPV) can be transmitted to humans or cats.


By Dr. Shari Sims, DVM

Dr. Sims received her Bachelor of Science with Honours from the University of Guelph in 1992 and her Doctor of Veterinary Medicine from the Ontario Veterinary College in 1997. She started working at an animal hospital at age of 15, and has done so ever since.