Canine ParvoVirus (Parvo) is a highly contagious disease caused by Canine ParvoVirus type 2 (CPV-2). There are several strains of CPV-2 and they all cause similar symptoms. The virus attacks white blood cells and the gastrointestinal tract of dogs and other canines such as coyotes, wolves and foxes.
In puppies, the virus can also damage the heart muscle.

All dogs are susceptible to Parvo, although some dogs are at greater risk than others. This includes puppies unvaccinated or that have not had sufficient mother's milk or incompletely vaccinated dogs, and certain breeds, such as:

  • Rottweilers
  • Doberman Pinschers
  • Bull Terrier Breeds
  • German Shepherds
  • English Springer Spaniels

What are the signs of canine parvovirus?

The signs of parvovirus infection vary from dog to dog, depending on the severity of the infection. These are some important signs to watch out for:

  • Lethargy
  • Loss of appetite
  • Vomiting
  • Severe, often bloody, diarrhea
  • Abdominal pain and bloating
  • Fever or low body temperature (hypothermia)

If your dog shows any of these signs, immediately contact your veterinarian. Persistent vomiting and diarrhea can quickly cause dehydration, and damage to the intestines and immune system can cause septic shock. This can lead to death, with most deaths occurring within 48 to 72 hours after signs first appear.

How is canine parvovirus spread?

Parvo is easily spread by direct contact with infected dogs, contact with feces (stool) from infected dogs, or contact with virus-contaminated surfaces. Such surfaces can include kennels, food and water bowls, collars and leashes, the hands and clothing of people who handle infected dogs.

The virus is resistant to heat, cold, humidity, and drying, and can survive in the environment for long periods. Even trace amounts of feces from an infected dog can contain the virus and infect other dogs.
This makes proper disinfection practices critical.

Because Parvo is highly contagious, dogs suspected or confirmed to be infected need to be isolated from other dogs to minimize spread of infection. Other strict infection control protocols also must be followed, including thorough cleaning and disinfection of any areas where the dog has been with products capable of killing the virus.

If your dog has the parvovirus infection, contact your veterinarian, they can recommend things you can do to help prevent parvovirus from spreading at home and elsewhere.

Feces of infected dogs contain a lot of virus and are a source of infection for other animals. The virus is ingested orally and enters the intestines via the stomach where it causes an intestinal infection.
Puppies up to one year of age are most susceptible to infection, while 80% of adult dogs that become infected show no symptoms.

The most effective way to protect a puppy against CPV is to vaccinate adequately at 6, 9 and 12 weeks of age. Younger puppies are usually well protected by antibodies in the mother's milk (passive immunity) but this disappears after a few weeks after which the vaccinations should provide active immunity. The vaccination should be repeated annually.

The virus is very stable in the environment and can remain infectious in the open air for a long time (months). The virus is resistant to most cleaning agents and alcohol. Parvovirus is also transmitted via shoes, clothing, baskets and toys of infected dogs.

After being infected, dogs usually become ill within a few days, but sometimes the first symptoms only appear after 2 weeks.

If an animal is not ill, but may be infected, a quarantine period should therefore last at least 2 to 3 weeks. After that, an animal can safely be placed with other potentially susceptible animals.

If an animal is ill, nursing in quarantine is necessary.
After recovery, the dog can still excrete the virus for 2 weeks. It is therefore advisable to keep the animal in quarantine during that period.

In addition to the intestinal form (gut), a much less common cardiac form is seen in puppies that are infected in the womb or just after birth. In these animals, the virus attacks the heart muscle and the puppies die quite quickly in the majority of cases.

How is canine parvovirus diagnosed and treated?

Your veterinarian may suspect Parvo based on the signs your dog is showing, your dog’s history, and other factors. Fecal testing can confirm the diagnosis.

Dogs with severe infection need immediate, intensive treatment and 24/7 monitoring—which often involves several days of hospitalization. Supportive care is provided to correct dehydration and physiological imbalances caused by vomiting and diarrhea, control nausea and pain, keep the dog warm, prevent other infections from happening, and provide nutritional support. Additional treatment may be recommended to help fight the infection and/or combat diarrhea. This can all be very expensive, and the dog may die despite treatment. Prompt, intensive treatment improves the chance of survival.

How can I protect my dog against canine parvovirus?

Vaccination and other preventive measures—including good hygiene—are key to avoiding canine parvovirus infection.

Young puppies are especially vulnerable to canine parvovirus. If a mother dog has antibodies against parvovirus, as can occur when she’s been vaccinated, then she may pass those antibodies to her newborn puppies through her milk. However, this natural immunity may wear off before the puppies' own immune systems are mature enough to fight off infection. And, if a puppy is exposed to the virus during this gap in protection, the dog may become ill. An additional concern is that immunity provided by a mother's milk may interfere with an effective response to vaccination. This means that occasionally even vaccinated puppies may become infected and become ill.

To reduce gaps in immunity and provide the best protection against canine parvovirus during the first few months of life, a series of vaccinations is recommended. The parvovirus vaccine is included in a combination vaccine that also protects dogs against some other common canine viruses.
This vaccine is considered “core,” and is recommended for all dogs.
Puppies younger than 16 weeks should receive their first dose at between 6 and 8 weeks of age, then two more doses 2-4 weeks apart.
Dogs older than 16 weeks with no previous vaccination or an unknown history should receive two doses 2-4 weeks apart.
To maintain protection, a booster dose of the combination vaccine is recommended within one year after the last dose in the initial vaccination series.
Afterward, boosters are recommended every three years.

If your adult dog hasn’t been vaccinated yet, or is overdue or missing some vaccinations, it’s not too late. Ask your veterinarian about a recommended vaccination program based on your dog’s age and needs.

These additional measures also can help protect your dog and other animals from canine parvovirus and other infectious agents:

  • Until the initial vaccination series is complete, use caution when bringing puppies to places where dogs gather. This includes pet shops, parks, puppy and obedience classes, doggy day cares, kennels, and groomers.
  • Choose establishments and training programs that require up-to-date vaccinations, health examinations, good hygiene, and isolation of sick puppies and dogs.
  • Keep your dog away from other dogs when sick, including other dogs within your home.
  • Avoid contact with known infected dogs and their premises.
  • Keep your dog away from other dogs’ feces.
  • Routinely collect and properly dispose of your dog’s feces.
  • If you’ve been in contact with dogs with or exposed to parvovirus, avoid handling other dogs, or wash your hands and change your clothes before doing so.