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Cornell Richard P. Riney Canine Health Center

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Parvovirus: Transmission to treatment

Canine parvovirus is a highly contagious and dangerous virus that affects primarily young, unvaccinated dogs. The virus causes life-threatening vomiting, diarrhea and dehydration. Vaccination is crucial to minimize the spread and exposure to our canine companions. 


Parvovirus can infect unvaccinated dogs of any age, but commonly affects puppies between the age of 6 weeks to 6 months. Dogs get exposed by ingesting the virus, which is shed in the feces of infected dogs up to two weeks before any symptoms develop, and two weeks after the signs resolve. Parvovirus is hardy in the environment and resistant to many household disinfectants, making it able to survive in the right conditions for up to a year. This makes it easier to spread even without any known direct contact with another dog. 

The virus attacks a few parts in the body, primarily the intestines, where it destroys the inside lining. This damage leads to bacteria leaking out of the intestines and into the bloodstream. Another site the virus targets is the bone marrow, which can weaken the immune system and lower the dog’s ability to fight infection. The combination of weakened immunity and overwhelming bacteria in the bloodstream can lead to life-threatening consequences and death if left untreated. 

Clinical signs 

The earliest signs of parvo begin with lethargy, followed by decreased appetite and vomiting. The signs typically progress quickly then to diarrhea which often contains blood and mucus, and has a foul odor. Other signs include: 

  • Lethargy 

  • Vomiting 

  • Diarrhea 

  • Decreased appetite 

  • Weakness 

  • Belly pain  

  • Fever 

  • Dehydration 


Any puppy or unvaccinated dog with signs of vomiting and diarrhea should be tested for parvovirus. A relatively quick and inexpensive test can be performed by looking for the virus in the feces or a swab of the rectum.  

Your veterinarian will likely also recommend blood work. Some dogs may be anemic from blood loss in the intestines, or have very low blood sugar levels from the combination of severe illness and lack of sugar reserves in young patients. Because there may be more than one cause of vomiting and diarrhea, additional tests may be performed such as X-rays, ultrasounds or additional fecal samples. 


IV fluids and management of electrolytes are the cornerstone of treatment for parvo. Antibiotics are given to prevent secondary infections, along with medications to help relieve vomiting, nausea and pain. De-wormer should be given since many puppies also have intestinal parasites that can worsen diarrhea. If the sugar levels are low, IV supplementation will be required. 

A newer treatment option for parvovirus is monoclonal antibody therapy. Canine parvovirus monoclonal antibody (CPMA) is a one-time intravenous injection that neutralizes parvovirus by binding and blocking the virus from entering and destroying cells. When administered at the time of diagnosis, CPMA can help lessen the severity of clinical signs of parvovirus in dogs.

Nutrition is a very important part of treatment. Since most patients are not eating enough on their own, some may require a temporary feeding tube that goes into their nose and directly into the esophagus or stomach to provide nutrients.

Severe cases may also need a treatment called a plasma transfusion, which helps replenish loss of clotting factors and blood proteins, such as albumin which are important for maintaining blood pressure. 

Patients with parvo require close monitoring and should ideally be hospitalized where they can receive the care and attention they need. However, in situations where there may be financial barriers to hospitalization, outpatient therapy has been successful for many dogs — as long as the owner can give medications and adhere to a rigorous schedule of daily checks with their veterinarian to ensure the dog is responding to treatment. 


Survival from a parvovirus infection is possible, but depends on age, size and how sick the dog is when owners first seek care. Most patients will not survive without treatment. Starting medical treatments when illness first sets in will increase the likelihood of recovery. 


The top three ways to prevent infection are: 

  • Vaccination 

  • Cleaning with appropriate disinfectants 

  • Avoiding high risk areas (dog parks, pet stores, etc.) when dogs are unvaccinated or still a puppy  

Parvovirus is a core vaccination for dogs and critical for protection against infection. Vaccination typically starts at 8 weeks (but may start as early as 4 weeks in shelter settings) followed by a booster every 2-4 weeks until 16-20 weeks of age. A booster is given the following year, and then generally every 3 years thereafter.  

Because parvovirus is very contagious and hardy in its environment, proper disinfection is crucial. Dogs with parvovirus should be isolated during their treatment, and for up to 2 weeks after recovery.  

Most common household cleaners will not kill parvovirus. Properly diluted bleach (1:30 ratio with water) is effective when left to soak for at least 10 minutes after all organic material (feces, food, etc.) has been already removed. Without disinfection or direct sun exposure, the virus may survive in the environment for months to years.   

Updated 4/24