Reviewed and updated for accuracy on March 4, 2020, by Dr. Katie Grzyb, DVM
The canine parvovirus (CPV) infection is a highly contagious viral illness that affects dogs. The virus manifests itself in two different forms.
More common is the intestinal form of parvo in dogs, which is characterized by vomiting, diarrhea, weight loss and lack of appetite (anorexia). Less commonly seen is the cardiac form, which attacks the heart muscles of fetuses and very young puppies, often leading to death.
The majority of cases of parvovirus are seen in puppies that are between 6 weeks and 6 months old. The incidence of parvo infections has been reduced radically by appropriate vaccination and boostering in puppies.
Here’s what you need to know about parvo in dogs.
Symptoms of Parvo in Dogs
The major symptoms associated with the intestinal form of parvo infection include:
Severe, bloody diarrhea
Anorexia (no appetite)
Fever or hypothermia (low body temperature)
Severe weight loss
The intestinal form of parvovirus affects the body's ability to absorb nutrients. A dog with parvo will quickly become dehydrated and weak from lack of nutrient and fluid absorption.
Vomiting and diarrhea, often containing blood, are the most common reasons that dogs with parvovirus are taken to the veterinarian. The wet tissue of the mouth and eyes may become noticeably red, and the heart may beat too rapidly.
When your veterinarian examines your dog’s abdominal area, your dog may respond due to pain or discomfort. Dogs that have contracted CPV may also have a low body temperature (hypothermia), rather than a fever.
How Is Parvo Spread?
There are a variety of risk factors that can increase a dog’s susceptibility to parvovirus, but it’s usually spread either through direct contact with an infected dog, or indirectly, by the fecal-oral route.
Parvovirus Can Live in Poop and in the Ground
Heavy concentrations of the virus are found in an infected dog’s stool. So when a healthy dog comes in contact with an infected dog’s stool (or anus), that dog can contract the disease.
The virus can also be brought into a dog's environment by way of shoes that have come into contact with infected feces or other objects that were not adequately disinfected.
There is evidence that the virus can live in ground soil for more than a year. It’s resistant to most cleaning products and even to weather changes.
Parvovirus Spreads Quickly in Kennel Environments
Breeding kennels and dog shelters that hold a large number of unvaccinated puppies are particularly hazardous places for parvovirus to spread. Shelters and rescue groups will often place puppies into foster homes until they are ready for adoption to minimize the risk of spreading parvovirus.
Even Vaccinated Puppies Could Get Parvovirus
How can vaccinated dogs get parvo? Puppies require a series of vaccinations to create an immunity to parvovirus. So if they miss a booster in the puppy vaccine series, they are prone to parvovirus.
And if they do not continue to receive lifelong boosters as recommended by their veterinarian, their antibody levels can drop too low and they will be susceptible to parvovirus.
Some pet parents choose to test their dog’s antibody levels with vaccine titers every year before getting the vaccinations. If antibody levels are low, vaccination is recommended.
Viral mutation can also lead to puppies being susceptible to other strains of parvovirus that are not contained in the vaccine.
This is why your veterinarian will want to revaccinate your puppy even if their records indicate they have had a vaccination.
Some Dog Breeds Are More Vulnerable
For unknown reasons, certain dog breeds, such as Rottweilers, Pit Bulls, Labrador Retrievers, Doberman Pinschers, German Shepherds, English Springer Spaniels, and Alaskan sled dogs, are particularly vulnerable to the disease.
Your veterinarian may recommend an extended vaccination protocol for these breeds.
How Do Vets Test for Parvovirus in Dogs?
Parvovirus is diagnosed with a physical examination, blood tests, and a special test for the parvovirus in feces. A urine analysis, abdominal x-rays, and abdominal ultrasounds may also be performed.
Low white blood cell levels and significant dehydration are indicative of CPV infection, especially in association with bloody stools.
Blood and urine analysis may reveal elevated liver enzymes and electrolyte imbalances. Abdominal x-ray imaging may show intestinal obstruction, while an abdominal ultrasound may reveal enlarged lymph nodes in the groin, or throughout the body, and fluid-filled intestinal segments.
You will need to give your vet a thorough history of your pet's health, vaccination history, recent activities, and onset of symptoms.
It’s important to retrace your dog’s steps for both possible exposure and potential contamination.
Is Parvovirus Treatable?
Since the disease is a viral infection, there is no real cure for it. Parvovirus treatment is focused on treating the symptoms and preventing secondary bacterial infections, preferably in a hospital environment.
Intensive therapy and systemic support are the keys to recovery.
Intravenous fluid and nutrition therapy are crucial in maintaining a dog’s normal body fluid after severe diarrhea and dehydration. Protein and electrolyte levels will be monitored and regulated as necessary.
Medications that vets may use to treat dogs with parvo include drugs to curb vomiting (antiemetics), antacids, gastroprotectants, antibiotics, and anthelmintics (vet-recommended dewormers) to fight parasites.
The survival rate in dogs is about 70% when treated in the vet hospital, but death may result from severe dehydration, a severe secondary bacterial infection, bacterial toxins in the blood, or a severe intestinal hemorrhage.
Prognosis is lower for puppies, since they have a less developed immune system. It’s unfortunately common for a puppy who is infected with CPV to suffer shock and sudden death.
How to Care for Your Dog After Parvo Treatment
Even after your dog has recovered from parvovirus, 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 still be contagious and able to spread parvo to other dogs for at least two months after the initial recovery. You will need to isolate your dog from other dogs for this period of time, and you may want to tell neighbors who have dogs that they will need to have them tested.
If you need to clean up a parvovirus-contaminated area, first pick up and safely dispose of all organic material (vomit, feces, etc.), and then thoroughly wash the area with a concentrated household bleach solution, one of the few disinfectants known to kill the virus.
Wash all of the objects your dog uses (e.g., dishes, dog crate, dog kennel, dog toys, bedding). It’s best to wash these items in the dishwasher or washing machine, and put bedding in the dryer.
Everything else should be deep-cleaned using a concentrated bleach solution as recommended by your veterinarian. This includes your clothes, shoes, and anything else that may have come in contact with your dog or infectious material.
If a dog has had parvovirus in a home, it is best not to have a puppy in that home for several years. Parvovirus is highly contagious and you do not want to put any other dogs at risk.
How to Prevent Parvo in Dogs
The best prevention you can take against parvovirus is to follow the correct protocol for vaccination. Young puppies should be vaccinated beginning at 6-8 weeks of age, then every three to four weeks until they are 16 weeks old. So a puppy that is first vaccinated at 6 weeks would then be vaccinated at 9 weeks, 12 weeks, and 15 weeks.
High-risk breeds may require a longer initial vaccination period of up to 22 weeks. During this time, your puppy should only socialize in private areas with fully vaccinated dogs.
Avoid all public areas where dogs spend time, including the dog park, dog beach, pet stores, dog-friendly restaurants, farmers markets, and other dog-designated areas.
Always pick up your dog’s feces immediately. This is a good habit to start immediately, as it reduces environmental contamination and the spread of intestinal parasites.
Parvovirus is a disease with serious consequences. Fast action by you and your veterinarian gives your dog the best prognosis for a full recovery.