Nothing is more pitiful than seeing our fur-babies ill. Canine parvovirus is a highly contagious virus that can infect puppies and adult dogs, potentially causing severe disease. In honor of National Immunization Awareness Month, The Meowing Vet explains the ins-and-outs of parvovirus (seriously, it causes terrible vomiting and diarrhea, so there’s a lot of “outs” 💩). Learn how you as a pet owner can protect your dog from infection.
Parvovirus, commonly simply called “parvo”, is a highly contagious virus shed in the feces of infected canines. Though any dog can be affected, breeds such as pit bulls, rottweilers, and dobermans are at increased risk of infection. Parvovirus can be spread directly from dog to dog or due to exposure with surfaces or objects that have been in contact with the fecal matter of infected dogs. Strict isolation of the infected puppy from other puppies or unvaccinated adult dogs is necessary to prevent the disease from spreading.
Viral particles are also highly resistant to destruction by many cleaners that may be effective in killing other viruses. Bleach is one of the only cleaners effective against parvovirus, and surfaces such as flooring as well as bedding, food and water bowls, and toys in which an infected puppy has been in contact should be thoroughly cleaned with bleach in order to clean these materials. A dog owner’s hands and clothing should also be thoroughly cleaned after handling a parvo puppy prior to contacting another dog.
Signs of Parvovirus
Parvovirus can cause one or a combination of three major syndromes in dogs:
1) Generalized neonatal disease (rare)
2) Myocarditis (uncommon)
3) Enteritis (very common)
Generalized Neonatal Disease
Generalized neonatal disease occurs if a newborn puppy (i.e. a neonate) is infected with parvo prior to 10 days of age. It sadly causes 100% case fatality and is incurable. However, this form of disease is rare because if nursed appropriately, most puppies of this age should have protective antibodies against parvovirus acquired from their mother’s milk.
Myocarditis
Myocarditis is inflammation of the heart muscle. It occurs if a puppy fetus is infected prior to birth (i.e. if its pregnant mother is infected and passes the virus to her unborn puppies through the placenta). Myocarditis can also occur in puppies infected with parvovirus before 8 weeks of age. Signs of myocarditis include quick onset of congestive heart failure (exhibited by difficulty breathing due to fluid development in the lungs) or sudden death. The signs of myocarditis may take up to 6 weeks to 6 months to develop after the initial parvo infection from which the young pup seemed to have recovered. Management of these cases involve treating the secondary congestive heart failure. However, prognosis tends to be poor.
Enteritis
Enteritis, or intestinal inflammation, is the most common manifestation of canine parvovirus. The parvovirus affects the intestinal villi, or the tiny fingerlike projections off the inner lining of the intestinal tract that functions to absorb nutrients. Therefore, not only do these puppies and adult dogs suffer from severe vomiting and diarrhea (which is often foul-smelling and bloody, a.k.a. hematochezia) and subsequent dehydration, but they also cannot fully utilize nutrients from their food due to malabsorption (failure to absorb nutrients). Hypoglycemia (or low blood glucose) can occur due to malabsorption or from secondary infection in which bacteria use up the puppy’s glucose supplies. Hypoglycemia can lead to seizures if blood sugar drops too low. Accompanying signs of GI involvement include decreased appetite (anorexia), lethargy, and fever. Another potential consequence of parvo enteritis is intussusception, a painful condition in which a portion of the intestines slide in on itself, causing an obstruction that can be fatal if not treated by your vet.
In addition to affecting the GI tract, parvovirus also attacks your dog’s immune system, resulting in panleukopenia, or destruction of disease-fighting white blood cells. This impairment of your dog’s white blood cell number and function makes him or her more susceptible to other infections. Even with proper supportive therapy, many puppies may die within 2 days of either severe dehydration or sepsis caused by secondary bacterial infections. Read more below to learn how these cases are treated…
Less Common Syndromes
Less common conditions can also occur with parvovirus, including neurologic impairment or disease to the skin, known as erythema multiforme that results in ulcerations to the foot pads and mucosal lining of the oral cavity and urogenital (urinary and reproductive) tracts. Variations in the virulence (or severity) of parvovirus in different regions of the world exist. Exposure to the virus by some canine individuals may not cause noticeable signs of disease depending on strain virulence as well as a dog’s level of immunity and overall health.
Learn about other common causes of canine vomiting and at-home treatments. Click here.
Diagnosis
Parvovirus will be suspected by your veterinarian in any young puppy or unvaccinated adult dog with vomiting and diarrhea. (Yes, this even includes adult dogs who had received parvo vaccines in the past but are not currently up-to-date due to lapses in regular boosters.) A fecal sample will be collected from the sick puppy or dog to be tested for evidence of parvovirus antigen (or a protein on the virus surface that triggers a response from the dog’s immune system). If your vet is concerned about an error on the antigen detection test, a type of Enzyme Linked ImmunoSorbant Assay (ELISA) test, he or she may wish to run further testing.
Bloodwork will also be performed to monitor for dehydration and electrolyte imbalances, hypoglycemia (low blood sugar), and panleukopenia (or low white blood cells). Some puppies will also be anemic (showing low red blood cells on bloodwork).
Curious about interpreting your dog or cat’s bloodwork results?
Click here to learn how to decipher this important diagnostic tool.
Treatment
Therapy for the classic form of enteritis syndrome caused by canine parvovirus involves supportive care to manage its side effects rather than curing the viral infection. Rather, time is needed to allow for your dog’s body to work on clearing the actual virus.
Your puppy will require hospitalization for several days in strict isolation from other dogs at the clinic. To optimize your dog’s health while it is fighting the virus, IV fluids are often required to correct dehydration and electrolyte imbalances, IV dextrose (a type of sugar) is commonly given to stabilize blood glucose levels, anti-nausea medications (like Cerenia®) are used, and IV antibiotics (such as ampicillin) are administered to fight off secondary bacterial infections. Depending on the severity of your puppy’s blood cell abnormalities, a blood transfusion may be in order. Some veterinarians may also give oseltamivir (such as over-the-counter Tamiflu® for humans) in the thoughts that this medication may fight off the parvovirus directly; however, the benefit of oseltamivir in parvo puppies is inconclusive.
For biosecurity measures, some veterinary clinics refuse to hospitalize parvovirus cases to prevent hospital contamination and the possibility of spreading the virus to other dogs in the hospital. These cases are either managed at home with the owner administering subcutaneous fluids (fluids under the skin) with antibiotics and anti-vomiting medications or else may regretfully end in euthanasia.
Sadly, even with proper treatment by your vet, many patients unfortunately die from dehydration or sepsis, often within 48 hours. The prognosis is worse for younger puppies and smaller breed dogs, resulting in a higher mortality rate for these individuals. If your puppy survives its battle against parvovirus, it will likely be immune from reinfection for the remainder of its life.
Prevention
Preventing parvovirus is so much better than attempting to treat it. Properly vaccinating your puppy against parvovirus is a necessity. The parvo vaccine is a core vaccine, meaning one that is highly recommended to prevent infection by a common environmental disease agent that can lead to severe infection or death. The parvo vaccine is most commonly administered in a combination vaccine (termed DHPP), which inoculates your puppy against distemper, hepatitis (adenovirus), parvovirus, and parainfluenza. This combo vaccine is injected by your vet as a series of vaccines every 3 weeks for 3-4 vaccine appointments, often at 6, 9, 12, and 15 weeks of age. Some vets prefer postponing initial vaccines until your pup is 8 weeks old, and many veterinarians also recommend a final booster at 18 weeks of age.
Why vaccinate an older puppy at 18 weeks old? When puppies are born, they receive many protective antibodies against parvovirus from their mother’s milk. Their maternal antibodies decline around 18 weeks of age, leaving your puppy potentially more susceptible to parvovirus infection around this age. It takes around 3-4 weeks after a vaccine is administered for your dog to be at his or her most protected state. If your puppy’s last vaccine was at 15 weeks of age, and his maternal antibody protection declines at around 18 weeks old, there may be a lag time of up to a week or a bit longer where the vaccine is not yet fully protecting your puppy against parvo. The best way to prevent parvovirus until your puppy is older than 18 weeks old is by strict isolation and proper hygiene. This means no puppy playdates, no doggie daycare, no visits to the groomer, etc., until your puppy has completed his vaccine series and is over 18 weeks of age.
And keep your adult dog up-to-date on his or her parvo vaccine too! Don’t let the term “parvo puppy” fool you; parvovirus can occur in older dogs, too. I firsthand have seen some cases in adult dogs. Depending on the severity of parvovirus in your area, your vet may recommend boostering your adult dog’s parvo vaccine annually or every 3 years. Protect both your mature dog and puppies in your area by heeding your vet’s advice and keeping your furry friend up-to-date on his or her vaccines.
Ideally, the DHPP vaccine should be purchased from and administered by your veterinarian. All too often have I seen local outbreaks of parvovirus in puppies who have been vaccinated by their owner with a vaccine purchased at a local agricultural and livestock supply store. Improper storage and refrigeration of these vaccines render them useless, wasting your money and leaving your dog susceptible to disease. Do yourself and your dog a favor by scheduling a vet appointment for innoculation rather than a trip to your nearby feed store.
Click here to learn more about puppy and dog vaccinations, including the vaccine against parvovirus. Want more insight on canine parvovirus? Click here.
What about cats?
Kittens, and unvaccinated adult cats to a lesser extent, can also be affected by feline strains of parvovirus. Don’t worry though; the canine parvovirus strain is not the same as the feline version, so puppies and adult dogs with parvo are not a danger to your unvaccinated kitty… just to other dogs. Feline parvovirus is also known by its other names: feline panleukopenia virus (for the syndromes that the virus causes) and feline distemper virus (not to be confused with canine distemper, which is an altogether separate virus from canine parvovirus).
Kittens with feline parvovirus not only develop the GI effects that puppies do (severe vomiting and diarrhea) as well as panleukopenia (decreased white blood cells), but if infected before birth (i.e. during their mother’s pregnancy), they develop cerebellar hypoplasia. Cerebellar hypoplasia is impaired growth and development of the cerebellum during pregnancy. The cerebellum is the region of the brain responsible for balance and coordinated movements. If these affected kitties survive infection, they will always have impaired neurological development and have very jerky and uncoordinated movements for the remainder of their lives (as seen in the video below). Unneutered male and female cats that are infected may also have impaired reproductive ability later on in life.
Just as for puppies, proper vaccination of kittens and adult cats can greatly reduce the chance of feline parvovirus infection. Click here to learn more about the feline parvovirus vaccine and other vaccines for cats and kittens.
Visit The Meowing Vet’s website later on for a future article on Feline Parvovirus (a.k.a. Feline Distemper or Panleukopenia) to learn more about Cerebellar Hypoplasia.
– Maranda Elswick, DVM
If you have any suspicion that your puppy or adult dog is displaying signs of parvovirus, The Meowing Vet advises you to isolate it from other canines and to seek veterinary attention immediately.
