What is Parvovirus?

Parvo is an extremely contagious and usually deadly disease of puppies. It is most common in puppies under one (1) year of age, but can infect older dogs.

How does a puppy get Parvo and what happens?

The virus can be spread through the feces of a dog that has been infected, or it can be in the environment. Parvo is an extremely hardy virus and can be transmitted from contaminated areas outside to indoors via shoes or pet feet. Dogs that have had parvo and recovered can still shed the virus up to two weeks after they have recovered.

The virus enters the body through the mouth as the puppy cleans itself or eats food off the ground or floor. A minuscule amount of infected stool is all it takes.

There is a 3-7 day incubation period before the puppy seems obviously ill.

Upon entering the body, the virus seeks out the nearest rapidly dividing group of cells. The lymph nodes in the throat fit the bill and the virus sets up here first and replicates to large numbers. After a couple of days, so much virus has been produced that significant amounts of it have been released into the bloodstream. Over the next three to four days, the virus seeks new organs containing the rapidly dividing cells it needs: the bone marrow and the delicate intestinal cells.

Within the bone marrow, the virus is responsible for destruction of young cells of the immune system. By killing these cells, it knocks out the body's best defense and ensures itself a reign of terror in the gastrointestinal (GI) tract where its most devastating effects occur. The GI tract is where the heaviest damage occurs. The virus damages the GI tract in a way that nutrients cannot be absorbed. Diarrhea in large quantities results, not to mention nausea. The barrier separating the digestive bacteria from the blood stream breaks down. The diarrhea becomes bloody and bacteria can enter the body, causing widespread infection (remember that that virus has also simultaneously destroyed the immune system’s ability to respond). The virus kills dogs in one of two ways:

• Diarrhea and vomiting lead to extreme fluid loss and dehydration until shock and death result.
• Loss of the intestinal barrier allows bacterial invasion of potentially the entire body. Septic toxins from these bacteria result in death.

How do I know if my puppy has Parvo?

It is important to confirm the diagnosis of parvovirus before embarking on what could be the wrong. A parvo test can be performed in the vet’s office in about 15 minutes or less. Please call your vet office before bringing in your pet as special precautions will need to be taken to protect other pets.

The mother of the puppies is vaccinated. Shouldn't that protect the puppies too?

No!

While puppies receive some of the maternal antibodies from colostrum (the milk the mother produces for the first two days after giving birth), several factors combine to make this insufficient to protect puppies.

First, how much colostrum an individual puppy gets depends on its birth order and how strong it nurses; not all puppies get the same amount of antibodies.

Second, every nine days the antibody levels possessed by the puppies drops by half. When the antibody level drops to a certain level, they no longer have enough antibody to protect them and if they are exposed to a large enough number of viral particles, they will get infected.

How is survival possible?

Whether survival is possible amounts to a race between the damaged immune system trying to recover and respond versus the fluid loss and bacterial invasion.

Hospitalization with IV fluids and intensive supportive care greatly increases, but doesn't guarantee, the chance of survival. Because the virus has destroyed the GI tract, medications are not effective when given orally.

 Treatment for parvovirus infection centers on what is called supportive care. This means that the veterinarian’s job is to keep the patient hydrated, comfortable and as strong as possible so that the puppy has time and ability to generate an effective immune response. We cannot kill the virus inside the patient's body; only the immune system can do that. The basic treatment principles involve IV fluid therapy with additional electrolytes based on bloodwork results, IV antibiotics, control of nausea and nutritional support.

 Other tests should be run to make sure there are no concurrent diseases. For example, the vet will check for intestinal parasites (worms). The last thing these patients need is a parasite burden contributing to their nausea and diarrhea.

 Hospital monitoring (bloodwork) is also essential. One of the first acts of the parvovirus is to shut down the bone marrow production of immunologic cells (the white blood cells). White blood cell counts are often monitored as the infection is followed. The white blood cell count bottoms out at the height of the viral infection and recovers as the patient’s immune system gains the upper hand. Following the white blood cell count is helpful in tracking the course of infection and determining when the patient is truly on the upswing. Electrolyte and glucose levels are also important to monitor.

 Abdominal palpation will often be performed due to an issue called intussusception. Sometimes an area of intestine actually telescopes inside an adjacent area in a process called intussusception. This is a disastrous occurrence as intussusception can only be treated surgically and parvo puppies are in no shape for surgery. Euthanasia is usually elected in this event.

 Total blood protein will also be monitored. Protein depletion is common when there is heavy diarrhea. If blood proteins drop too low, certain IV fluids or even plasma transfusions are needed to prevent massive life- threatening edema.

Prepare for a 5-7 day hospital stay and expense! This is one reason responsible vaccination is the better choice - it’s less expensive!

Home treatment for Parvo?

Proper treatment for parvo involves intensive support and monitoring of numerous parameters that may require special, additional treatment.

Survival statistics with hospitalization are high and there is no comparable treatment that can be performed at home. That said, sometimes financial concerns preclude hospitalization and home care may be a puppy's only chance. The owner will need to give injections, manage feedings, and clean up a great deal of vomiting and diarrhea.

If home treatment turns out to be the only option, ask your veterinarian about how to accomplish this.

Prevention, prevention, prevention!

It should not be too surprising that the biggest step in preventing parvovirus is vaccination. A puppy should have their first parvo vaccine at six (6) weeks and a booster every three (3) weeks after that until they reaches the age of 16 weeks.

We recommend that puppies be restricted from public outdoor areas until their vaccination series is completed at the age of 16 weeks. There is a period of a week or so during which the puppy has no antibody protection left over from its mother but still is not yet competent to respond to vaccination. This window is where even the most well cared for puppies get infected. This means not going for walks or to the park and not socializing with other puppies.

Prevention is about minimizing exposure to the virus until the vaccination series is completed.

Where does a puppy get Parvo?

A parvoviral infection can be picked up anywhere, although it is easier to pick up an infection in an area where an infected dog has been simply because of the larger amounts of virus in a contaminated area. A typical/average infectious dose for an unvaccinated dog is 1000 viral particles. An infected dog sheds 35 million viral particles (35,000 TIMES the typical infectious dose) per OUNCE of stool. Parvo can survive in the environment because it is not easily killed by freezing temperatures or time.

I know my puppy had Parvo - What do I do to disinfect my house?

If the home has previously housed a parvo infected dog or puppy, disinfection (especially removing fecal matter) is paramount. Given that this is such a tough virus to destroy, many people want to know exactly what they must do to disinfect an area that has contained an infected dog or how long they must wait before safely introducing a new dog to a previously contaminated area. Here is what we know about how contaminated an environment is likely to be:

• Infected dogs shed viruses (in their stool) in gigantic amounts during the 7 to 10 days following exposure. Because such enormous amounts of virus are shed, there is a HUGE potential for environmental contamination when an infected dog has been there.
• Despite the introduction of new cleaners with all sorts of claims, parvovirus remains virtually impossible to completely remove from an environment. The goal of decontamination is to reduce the number of viral particles to an acceptable level.
• Bleach completely kills parvovirus. One-part bleach is mixed with 30 parts water and is applied to bowls, floors, surfaces, toys, bedding, and anything contaminated that is colorfast or for which color changes are not important. At least 10 minutes of contact time with the bleach solution is needed to kill the virus. Steam cleaning for cloth/carpets is also able to kill the virus.

What other areas do I need to disinfect?

Outdoor decontamination:

• Freezing temperatures have no effect on the virus. If the outdoors is contaminated and is frozen, you must wait for it to thaw out and warm up before safely introducing a new puppy. Outdoors, if good drainage is available, thorough watering down of the area may dilute any virus.
• Shaded areas should be considered contaminated for seven (7) months.
• Areas with good sunlight exposure should be considered contaminated for five (5) months.
• When in doubt, make the new puppy an older individual (16 weeks or so) who has already completed his/her vaccination series.