Parvovirus or Parvo is a viral disease that affects dogs. The disease is highly infectious and is spread from dog to dog by direct or indirect contact with their feces. It can be especially severe in puppies that are not protected by maternal antibodies or vaccination. It has two distinct presentations, a cardiac and intestinal form. It is far more common in puppies than adult dogs and can have serious ramifications for the infected animal, including death. Parvo grows best in the rapidly dividing cells of the dog’s intestines. As the virus attacks and kills these cells it causes massive diarrhea and halts or slows the creation of white blood cells. In young puppies it can often directly infect the heart, leading to death.
The symptoms of Parvo start with fever, depression, and lethargy. The dog will usually experience a loss of appetite as well and then eventually show more sever signs like vomiting and diarrhea which is often bloody. Once the virus reaches this stage dehydration and death usually follow.
Parvo is carried and transmitted by dogs. The vomit and feces of an infected animal will also carry the virus which is rather resilient and can survive outside the dog’s body in the surrounding environment for as long as nine months. Sometimes an adult dog can be infected by the virus and show no symptoms but act as a carrier transmitting the virus to the other animals it comes into contact with.
There is no cure for Parvo. Dogs that are infected will die of dehydration without treatment. That treatment primarily consists of providing fluids, giving repeated blood transfusions, and preventing dehydration. The mortality rate in dogs affected by Parvo is about 20% if the dog receives treatment in time. Without treatment, about 80% of those infected will die from it. It is a very serious disease.
Parvo tends to affect some dog breeds more than others. Dobermans, Rottweilers, and other black and tan dogs have a greater chance of contracting the virus. The reason for this is unknown but the fact that these dogs are at higher risk does not mean that owners of other types of dogs can rest easily. Dogs of any breed can become infected.
While there is no cure for Parvo, puppies can (and should) be vaccinated against it at an early age. Most vets recommend puppies be immunized starting at six weeks of age with vaccinations continuing until twenty weeks of age. Proper immunization is the best way to prevent a dog from contracting Parvo.
Treatment ideally consists of crystalloid IV fluids and/or colloids, antinausea injections such as metoclopramide, dolasetron, ondansetron and prochlorperazine, and antibiotic injections such as cefoxitin, metronidazole, timentin, or enrofloxacin. IV fluids are administered and antinausea and antibiotic injections are given subcutaneously, intramuscularly, or intravenously. The fluids are typically a mix of a sterile, balanced electrolyte solution, with an appropriate amount of B-complex vitamins, dextrose and potassium chloride.
In addition to fluids given to achieve adequate rehydration, each time the puppy vomits or has diarrhea in a significant quantity, an equal amount of fluid is administered intravenously. The fluid requirements of a patient are determined by their body weight, weight changes over time, degree of dehydration at presentation and surface area.
The hydration status is originally determined by assessment of clinical factors like tacky mucous membranes, concentration of the urine, sunken eyes, poor skin elasticity and bloodtests. A blood plasma transfusion from a donor dog that has already survived CPV is sometimes used to provide passive immunity to the sick dog. Some veterinarians keep these dogs on site, or have frozen serum available. There have been no controlled studies regarding this treatment.
Additionally, fresh frozen plasma and human albumin transfusions can help replace the extreme protein losses seen in severe cases and help assure adequate tissue healing. Once the dog can keep fluids down, the IV fluids are gradually discontinued, and very bland food slowly introduced. Oral antibiotics are administered for a number of days depending on the white blood cell count and the patient’s ability to fight off secondary infection.
A puppy with minimal symptoms can recover in 2 or 3 days if the IV fluids are begun as soon as symptoms are noticed and the CPV test confirms the diagnosis. However, even with hospitalization, there is no guarantee that the dog will be cured and survive.