Parvovirus: Disease With Serious Consequences

By Deb Haines

Vaccinating your puppy is one of the most important things you should do in your first few weeks as a dog owner. Regular vaccinations help puppies grow into dogs who remain free of infectious diseases, and also prevents them from passing nasty diseases on to other animals in the local area.

Canine Parvovirus Infection in Puppies/Dogs

The canine parvovirus (CPV) infection is a highly contagious viral illness that affects dogs/puppies. The virus manifests itself in two different forms.

The more common form is the intestinal form, which is characterized by vomiting, diarrhea, weight loss and lack of appetite (anorexia). The less common form is the cardiac form, which attacks the heart muscles of fetuses and very young puppies, often leading to death.

The majority of cases are seen in puppies that are between six weeks and six months old. The incidence of canine parvovirus infections has been reduced radically by early vaccination in young puppies.

Signs & Symptoms of Parvo in puppies/dogs

The major symptoms associated with the intestinal form of a canine parvovirus infection include:
– Severe, bloody diarrhea
– Lethargy
– Anorexia
– Fever
– Vomiting
– Severe weight loss

The intestinal form of CPV affects the body’s ability to absorb nutrients, and an affected animal will quickly become dehydrated and weak from lack of protein and fluid absorption.The wet tissue of the mouth and eyes may become noticeably red, and the heart may beat too rapidly.

Parvovirus: Vaccination and Prevention

The biggest step in preventing parvovirus is vaccination. As discussed in other sections, the virus exists virtually everywhere. It is hardy in the environment and easily carried on the surfaces of inanimate objects. Every dog will be exposed and every puppy will be vulnerable at least for a time.

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

Because of parvovirus, puppies should not be allowed out in the public world until their vaccine series has been completed. This means not going for walks or to the park and not socializing with other puppies


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 GI tract where its most devastating effects occur. All parvoviral infections are characterized by a drop in white blood cell count due to the bone marrow infection.

The GI tract is where the heaviest damage occurs. The normal intestine possesses little finger-like protrusions called villi. Having these tiny fingers greatly increases the surface area available for the absorption of fluid and nutrients. To make the surface area available for absorption greater still, the villi possess microvilli, which are microscopic protrusions. The cells of the villi are relatively short-lived and are readily replaced by new cells.

The source of the new cells is the rapidly dividing area at the foot of the villi called the crypts of Lieberkuhn. Parvovirus strikes right at the crypt. Without new cells coming from the crypt, the villus becomes blunted and unable to absorb nutrients. 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 bone marrow’s ability to respond immunologically).

The virus kills puppies/ 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 is Survival Possible?

Even parvovirus cannot disrupt the entire immune system. Plus, every day that goes by allows more antibodies to be produced. This antibody can bind and inactivate the virus. 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.

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.

Be prepared for a 5-7 day hospital stay and substantial expense. Intensive care is needed to treat this infection.

The following tests are helpful in adjusting parvovirus treatment:
– Fluid Therapy
– Antibiotics
– Control of Nausea
– Monitoring
– Fecal flotation to rule out worms/internal parasites
– White blood cell counts/complete blood counts
– Electrolytes and Glucose levels
– Urine Specific Gravity/Lactate Levels
– Abdominal Palpation
– Total blood protein

This information is provided by Wendy Brooks, DVM, DABVP

Living and Management

Even after your dog has recovered from a CPV infection, they will still have a weakened immune system for some time, and will be susceptible to other illnesses. A high-quality, easily digestible diet is best for your dog during recovery.

Your dog will also continue to be a contagion risk to other dogs for at least two months after the initial recovery. You will need to isolate your dog from other dogs or a period of time, and you may want to tell neighbors who have dogs that they will need to have their own pets tested.

Wash all of the objects your dog uses (e.g., dishes, dog crate, dog kennel, dog toys). Machine washing is best—anything that can go into the dishwasher or washing machine and dryer should. Everything else should be deep-cleaned using a concentrated bleach solution as recommended by your veterinarian.

Recovery comes with long-term immunity against the parvovirus, but it is no guarantee that your pet will not be infected with the virus again

Parvo virus is a disease with serious consequences. Fast action by you and your veterinarian gives your dog the best prognosis for a full recovery.

Questions and Answers ( These are member questions and PVC vet responses)

1) My dog died from parvo. He was fully vaccinated. At 7 weeks he had protech c3 and at 12 weeks duramune c4, Why would he have died?

Dr.Nesselroad ……Multiple factors could have contributed to the vaccines failing if your pet did contract parvo. First – who gave the vaccines? If vaccines were not given by a veterinarian, I would not consider him UTD. Many people try to save money by giving their own vaccines from a feed store or other source but they are often not stored at appropriate temperature making the vaccine ineffective. If a pet comes to me from a breeder or someone vaccinating their own pets, I highly recommend starting over, even if they are over 16weeks old. Another issue is your vaccine timing. It is recommended to booster the vaccine 2-4 weeks after the initial. With his being 7 and 12 weeks old, that is a 5 week window. Gold standard also says to vaccinate them until 16 weeks of age. It would have also been recommended to booster his vaccine 1 year from his 12 week vaccine.

2) My dog died of parvo recently, Is it safe to bring in a new puppy?

Dr.Nesselroad…..I recommend not getting a puppy in the same environment for at least 7-10 years. Parvo is a very hardy virus that can live in the ground and environment for a very extended period of time. If you were to get a new dog in the same environment, I would recommend an older (2-3years), completely vaccinated dog. No vaccine is ever 100%. So many reasons the vaccines could have failed. Titer testing is often expensive. It can be 3x or more the cost of a vaccine. Especially young dogs, I recommend vaccinating over titer testing if no other auto-immune issues are present.

3) How long does parvo last in the environment?

Dr. Kate Wamack Black….It can stay in the environment for years and years. A client got a new puppy 10 years after they had one succumb to parvovirus. They didn’t let the puppy outside, kept it in the bathroom, never letting it in the yard. It too broke with parvo but lived. There is a chance that it had been exposed prior to them getting it, but the most likely explanation is that parvo remained at the house and the puppy picked it up there.

Dr.Virginia Lashley… Please keep in mind that everything you touch in that house is covered in parvo. Then YOU are covered in parvo. So strip naked at your door and throw your clothes in the wash immediately to avoid exposing your new puppy including shoes then shower immediately

4) What can i use in and around my home to kill Parvo virus on toys, bowls etc ?

Dr. Sara Castro…..The only way to kill the virus is bleach.

Dr.Dina Hartzel Wild…. the critical thing with bleach is that it needs to be used AFTER biological or organic material is removed. It’s inactivated otherwise.

5) I was told me that Black and Tan dogs are more prone to getting Parvo-Virus… is this true?

Dr. Claire Tousley Klatt ……Not sure I’d phrase it quite that way, but some breeds such as Rotties tend not to respond appropriately to a normal vaccination protocol and may still be at risk after a normal puppy series of distemper/parvo vaccinations.

6) I was wondering if dogs can still get parvo even if they are fully vaccinated/up to date on their shots?

Dr. Dina Hartzel Wild….. The key thing is no vaccine can be promoted as 100%. So much depends on vaccination timing and individual immune response to vaccination. Even if everything was perfectly timed and the vaccines perfectly handled, there is no guarantee that the individual mounted an appropriate immune response. Obviously vaccination will turn a substantial risk into a ridiculously minuscule risk, but 100%? Can’t say that.

Dr. Maria Patink….Being properly vaccinated against parvovirus drastically reduces the chances of your dog getting sick with the virus,but there is absolutely nothing in medicine that is ever 100% (as Dr. W explained above)

7) My dog was vaccinated but still picked up Parvo

Dr. Bethany Moats.. If dog was vaccinated by your veterinarian, all vaccine companies I know of guarantee their products and will pay for the cost of treatment, provided the vaccines were given on the appropriate schedule and by a veterinarian. What is the percentage or possibility of dogs getting the parvovirus If fully & properly vaccinated against it?

Dr. Virginia Lashley.…if fully and properly vaccinated with 3 vaccines given by a veterinarian ending at 16 weeks of age and boostered properly at 1 year of age, the chances of getting it are slim, very slim.

9) For a vaccinated dog, is the illness less severe? I thought vaccination meant they couldn’t get it.

Dr. Virginia Lashley… most cases the illness is less severe. As with any vaccinated individual, vaccines reduce the risk and severity, they don’t always 100% prevent it but certainly help with severity unless the individual has a faulty immune system that fails to respond appropriately to vaccines or is immuno compromised

10)When should we worry if puppy is acting sick ?

Dr. Joey Lloyd...Any newly adopted/rescued/purchased puppy who has diarrhea, stops eating or vomiting should go to their vet! Parvo is super common and I advice testing any vomiting/diarrhea puppy up until around 16-20 weeks (once finished vaccine series). These puppies are too fragile to wait and a quick search of recent posts will show you how prevalent and deadly parvo is. Vet ASAP and 🤞 it’s just an upset stomach and not parvo.

People need to know

(1) it’s an emergency and

(2) it’s preventable with vaccines and

(3) until you puppy is fully vaccinated (every three week vaccinations from 6wks to 16 weeks) they CANNOT go to places with other dogs.

Parvo is very contagious and lasts a long time in the environment


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