Parvovirus Infection in Dogs

Veterinarian listening to a puppy's heartbeat
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Parvo is a common and potentially serious viral disease in dogs. The virus is officially known as Parvovirus. The disease caused by this virus is commonly referred to as Parvo. The virus first appeared clinically in 1978, and there was a widespread epidemic in dogs of all ages. Since no dogs had been exposed or vaccinated (the vaccine didn't exist at the time), dogs of all ages died from the infection. The virus can "adapt" over time, and other strains of the virus have appeared since then, but properly administered vaccinations are the best protection. Canine Parvovirus is thought to be a mutation from the feline Parvovirus, also known as feline distemper virus.

Signs of Parvovirus Infection

There are three main manifestations of Parvovirus infection:

  1. Asymptomatic: No signs are seen. Common in dogs over 1 year old and vaccinated dogs.
  2. Cardiac: This form of the disease is much less common than the intestinal form due to widespread vaccination. Severe inflammation and necrosis (cell death), of the heart muscle, causes breathing difficulty and death in very young (less than 8 weeks of age) puppies. Older dogs that survive this form have scarring in the heart muscle.
  3. Intestinal: This virus causes extreme damage to the intestinal tract, causing sloughing of the cells that line the tract. This can leave the patient open to secondary bacterial infection. Most of the affected dogs (85 percent) are less than one year old and between 6-20 weeks old—before the full set of vaccinations can be given. The death rate from infection is reported to be 16-35 percent in this age group.

The intestinal signs include:

  • Lethargy
  • Vomiting
  • Loss of appetite
  • Diarrhea - usually bloody, and very foul-smelling (a characteristic odor, particular to Parvovirus infection)
  • Intussusception - when a section of the inflamed intestinal tract telescopes into itself. This is an emergency.
  • Fever

The onset of clinical signs is usually sudden, often 12 hours or less. The incubation from exposure to seeing the clinical signs varies from 3 to 10 days.

How Parvovirus Infection Is Diagnosed

This disease is diagnosed by physical examination, signalment (age, vaccination status, breed, etc.), and a fecal Parvo (ELISA) test. Additional diagnostics include blood work and radiographs. Dogs infected with Parvo typically have a low white count. Radiographs help rule out other potential causes of vomiting and diarrhea.

Parvovirus Treatment

There is no treatment specifically for the Parvovirus at this time. Treatment is supportive care, which includes any or all of the following:

  • Oral electrolyte fluids - if the case is mild and the animal isn't vomiting
  • Subcutaneous (SQ) or intravenous (IV) fluids to maintain hydration in the face of the extreme fluid losses from vomiting and diarrhea that are so typical of this disease
  • Anti-vomiting/nausea medications - to prevent further damage from vomiting and to keep the patient as comfortable as possible.
  • Antibiotics - because the virus has the potential to slough the intestinal tract, antibiotics help protect against secondary infection.
  • Blood or Plasma transfusions - to replace protein loss, provide antibodies, help with anemia.

Many puppies infected with Parvovirus need to be hospitalized for supportive care. Hospitalization is typically about five days, sometimes longer. Surviving the first three days is usually a good sign for long-term survival.

How Long Does Parvovirus Last in the Environment?

The Parvovirus family of viruses are particularly long-lived in the environment, lasting anywhere from 1 to 7 months—commonly surviving 5-7 months in an outside environment. Due to the large amounts of virus particles shed in the feces of an infected dog (shedding lasts two weeks or more after exposure) and the longevity of the virus, complete eradication of the virus is often impossible.

How to Disinfect an Area With Parvovirus

There are many Parvovirus disinfectants on the market, but regular old bleach is still 100 percent effective against Parvovirus. The dilution of bleach is one part bleach to 30 parts water. Caution is advised for dyed or colored fabrics or objects.

Do not use a bleach preparation on an animal at any time. The commercial Parvovirus disinfectants have the advantage of better smelling preparations. Check the label for colorfast warnings. See your vet or pet store for the various disinfectants available.

Be sure to keep feces (and any vomitus) picked up in the yard and kennel area as well.

How to Protect Your Dog From Becoming Infected

Vaccination is the key to preventing this disease and protecting your dog. Breeding bitches should be vaccinated before becoming pregnant to ensure that the pups get the best start at immunity. Vaccinations should start at 6 weeks of age, and be boostered at 9, 12, and 16 weeks of age. Some veterinarians also booster at 20 weeks, depending on the breed and Parvovirus risk in your area. Speak with your veterinarian about what vaccination protocol is the best for your pet and your lifestyle.

Some Breeds Are More Susceptible Than Others

It appears that some breeds, most notably the Rottweiler, Doberman Pinscher, German Shepherds, Pit Bulls, and Labrador Retrievers are at an increased risk for this disease. Conversely, Toy Poodles and Cockers appear to be at a reduced risk of contracting this disease. It is important to remember, however, that any breed can get Parvovirus. Be sure to keep your dog's vaccinations up to date.