Canine parvovirus: symptoms, causes, therapy and prevention


Canine parvovirus infection, called canine parvovirus, is an extremely contagious disease that affects domestic dogs, especially puppies and unvaccinated adult dogs.

Canine parvovirus affects the cells that line the digestive system. It is excreted in infected dog feces for several weeks. Transmission occurs through oral contact with infected fecal matter. Young, immunocompromised, stressed or sick dogs are particularly vulnerable.

Infected dogs expel canine parvovirus in the stool before manifesting the symptoms of the disease. That’s why parvovirus is highly contagious. The signs appear within 5-10 days after infection and lead to sudden and severe gastrointestinal discomfort. Infected dogs have profuse, foul-smelling and bloody diarrhea and deep abdominal pain. They also experience vomiting, develop high fever and lose weight.


As mentioned earlier, the dog excretes parvovirus in the stool for several weeks after contracting the infection. Clinical disease is caused by oral contact with infected fecal matter (fecal-oral transmission). When the dog licks or ingests something that has been contaminated with the parvovirus, it usually contracts the infection. Young dogs, immunocompromised, highly stressed and those suffering from other diseases are more susceptible to parvoviral infection. The incubation period for clinical parvoviral disease is approximately 5-10 days. However, infected dogs typically begin to expel the virus in the stool before manifesting the symptoms of the disease.

Canine parvovirus is present worldwide. It is most common in the seasons and in hot and humid environments and in spring, when most puppies are born. Canine parvovirus is very resistant to common household cleaners and disinfectants and can survive at room temperature, indoors or outdoors, for several months.



Most dogs begin to experience the symptoms of the disease after an incubation period of 5-10 days following exposure to the feces of an infected dog. Infected dogs typically begin to expel the virus in the stool before developing observable symptoms. In the acute phase of parvoviral disease, the owner of the animal can observe one or more of the following clinical signs:

  • Lethargy (usually appears suddenly, acute onset)
  • Diarrhea (profuse, often bloody, smelly)
  • Presence of mucus in the stool (steatorrhea)
  • Temperature (usually floating, it can be extremely high)
  • High heart rate (tachycardia)

Dogs most at risk

Parvoviral infection can affect dogs of any age, although most cases occur in young puppies between the ages of 6 weeks and 6 months. Unvaccinated or partially vaccinated animals have a considerably higher risk of developing parvovirus.

Some breeds are described as predisposed to canine parvovirus infection, such as Dobermann Pinscher, Rottweiler, English Springer Spaniel, German Shepherd, American Pit Bull Terrier and Dachshund. These races, once contracted the infection, also tend to develop more severe symptoms. The reason for this reduced resistance to parvoviral infection in these breeds is unknown. Also for unknown reasons, the Toy Poodle and Cocker Spaniel appear to present a reduced risk of canine parvovirus infection. Puppies whose mothers have been regularly vaccinated are also affected less frequently and less severely by parvovirus. This is because mother’s vaccination increases the levels of circulating maternal antibodies in young puppies.


Most veterinarians will begin evaluating the dog by collecting their medical history (patient’s medical history) and performing an accurate physical examination. Typically, the initial data collection includes blood and urine tests. The results of these analyzes can help the veterinarian to rule out or identify the presence of parvovirus.

For the identification of infectious organisms, they can be used faecal flotation and microscopic examination of the stool. However, the results of these tests are not reliable.

The veterinarian can recommend the execution of abdominal radiographs to rule out other causes of gastrointestinal discomfort, such as intestinal obstruction due to the presence of a foreign body or other forms of intestinal obstruction.

Currently, the best way to diagnose canine parvovirus infection is to identify viral antigens, which can be done by performing a ELISA test on a stool sample. The acronym ELISA means Enzyme-Linked Immunosorben Assay (Immuno-absorbent Dosage linked to an Enzyme). The results of this test can produce false negatives during the initial phase of the disease, before the period of maximum viral expulsion. False negatives can also occur after about 10-14 days of infection, when viral expulsion decreases rapidly. Dogs recently vaccinated against canine parvovirus with modified live vaccine may have false positives on the ELISA test for parvoviral infection.

More advanced and precise techniques for detecting parvovirus infection include the PCR test (polymerase chain reaction), electron microscopy, tissue cultures and viral isolation.


The immediate objectives of the treatment of canine parvoviral infection are: to reverse dehydration, electrolyte and metabolic alterations caused by the disease and to prevent or resolve secondary bacterial infections. The basic objectives are to eliminate pain, vomiting and diarrhea by restoring a good quality of life to the dog.

In most cases, dogs clinically infected with canine parvovirus need hospitalization and intensive medical care. Dehydration and electrolyte imbalances should be corrected as soon as possible by the administration of balanced fluids orally, subcutaneously or intravenously. A variety of medications are available to control severe diarrhea and vomiting, which typically accompany parvovirus infections. Many veterinarians recommend stopping food and water until dehydration, diarrhea and vomiting are controlled, which can take several days. However, some recent studies suggest that it may be better to encourage early nutritional support with high-protein, high-protein foods. Affected dogs, if reluctant to eat spontaneously, can be fed by means of a nasogastric or nasophageal tube until they have stabilized. Afterwards, a light diet is usually recommended. In particularly severe cases, the dog may need blood transfusions and / or other types of intensive care in hospitalization.

Parvoviral infection can be accompanied by secondary bacterial infections. For this reason, the attending veterinarian will most likely prescribe a cycle of broad-spectrum antibiotics to prevent the onset of a systemic bacterial infection (septicemia) and other bacterial complications, which can occur due to bacterial translocation through the damaged intestinal lining of the dog. .


The prognosis for dogs with parvovirus depends on a number of factors, including the virulence of the specific viral strain, the timeliness of diagnosis, the age and immune status of the dog at the time of infection and the timeliness with which he had I start the treatment. Other factors can also influence the diagnosis. If the infection is diagnosed quickly and treated aggressively, most dogs will fully recover and develop permanent immunity to the virus.


Newborn puppies are normally protected from parvoviral infection thanks to maternal antibodies, which they acquire in utero and through breast milk once they are born. These antibodies naturally decrease over time making puppies more susceptible to a range of infectious organisms, including canine parvovirus.

It is possible to prevent infection by vaccinating the puppies before they reach 8 weeks of age and repeating the vaccination again at intervals of 3-4 weeks until they reach 16 weeks of age. However, despite adequate vaccine prophylaxis, when maternal antibodies decrease and the animal’s immune system has not yet fully responded to vaccines, puppies have an increased risk of developing diseases due to infectious organisms.

To reduce the risk of infection for other animals, we recommend ensure a thorough disinfection of the areas / areas inhabited or frequented by infected dogs. Canine parvovirus is extremely resistant and can survive for months in the environment despite the presence of household cleaners. The most effective disinfectants in the case of canine parvovirus are bleach (in a 1:30 dilution with water) or potassium peroxymonosulphate. All surfaces with which an infected dog has come into contact must be thoroughly cleaned. Infected dogs, or dogs suspected of being infected, must be isolated from all other animals to limit environmental contamination and prevent the spread of the disease.

Historically, most authorities have recommended that healthy puppies be kept away from other dogs and especially from areas frequented by dogs whose vaccination status is unknown, until the completion of the vaccination cycle (approximately 16 weeks of age). However, more recent recommendations suggest that the benefits of early socialization with other dogs after the first vaccination may outweigh the risks of getting parvovirus infection. The pet owner should still discuss these potential risks and benefits with the veterinarian.

Adult dogs that have never been vaccinated before, receive two vaccinations 3 weeks apart. The vaccination will then be administered once a year or once every three years as a booster. Improper vaccine prophylaxis will result in incomplete immunization. This is why it is of fundamental importance to follow the guidelines relating to a correct cycle of vaccinations suggested by the veterinarian.

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