Parkside Animal Hospital / Parvovirus Infection In Dogs

PARVO INFECTION IN DOGS
by Kaye Wigginton, D.V.M.
published in July issue, Northeast Times

WHAT IS PARVOVIRUS (PARVO)?

'Parvo' is a serious, life threatening, highly contagious viral infection in dogs. It is currently the most common serious infection in dogs in the United States. Since its first clincal presentation in 1978, the virus has changed several times. CPV-2 was the original strain, and was replaced in 1980 by CPV-2A and in 1986 , the strain CPV-2B appeared. Last year, a team of veterinarians, virologists and pathologists at Oklahoma state University discovered the strain CPV-2C here in the United States. It has been in Italy for 6 years prior to its discovery here. This virus will most likely continue to "adapt" and change over time, much like the influenza (flu) virus in people.

HOW DO DOGS GET PARVO?

First, it is very important to realize that parvovirus is an extremely 'hardy' virus. It can live for very long times in the environment on inanimate objects (known as fomites) - soil, food, containers, floors, clothing, and on other household items, people's hands, shoes, etc. The virus is very resistant to extreme temperature changes; it will survive freezing and very hot temperatures. Detergents, alcohol or other common disinfectants, bleach and prolonged exposure to ultraviolet light will kill this virus directly. These are only effective if all the organic material is removed and the exposure time and concentrations of the solutions are correct. There are two types of transmission. Direct transmission occurs when an infected dog and a healthy dog come in contact with each other or with the infected dog's feces. This is called fecal-oral transmission. The virus is shed through the feces of the infected dog and is ingested by the healthy dog. Indirect transmission occurs when the virus is spread by fomites (inanimate objects) and people who have been exposed to the virus from the infected dog. Rodents and insects can also be vectors in the indirect transmission of this virus. Unvaccinated, improperly vaccinated or immune compromised puppies (typically under 6 months of age) are the most at risk for this deadly virus. Certain breeds (Rottweilers, Labradors, Doberman Pinschers and Pitt Bull Terriers) seem to be more susceptible also. Even though puppies are the most susceptible, adult dogs have been diagnosed also. The typical incubation period (time of exposure until signs of the disease appear) is 7-14 days. Excretion of the virus in the feces can start on the third day after exposure (even before the puppy appears to be sick) and can last 1-2 weeks after signs of the disease appear.

WHAT ARE THE CLINICAL SIGNS OF PARVO?

There are three main forms of the disease: Intestinal, Cardiac, and Asymptomatic. The intestinal form is the most common. The clinical signs of the intestinal form include lethargy, lack of appetite, vomiting, diarrhea (with or without blood visible) with a very foul odor, dehydration, fever, shock and death. The degree of severity of these signs can vary. Parvovirus actually kills the cells that line the intestines and they are sloughed out through the feces.

The clinical signs of the cardiac form include breathing difficulty and sudden death due to severe inflammation and death of the heart muscle. This form usually occurs in puppies less than 8 weeks old. Dogs that survive this form have scarring of the heart muscle.

With the asymptomatic form, there are no clinical signs. This form occurs more often in dogs over 1 year of age and vaccinated dogs.

HOW IS PARVO DIAGNOSED?

Parvo is diagnosed by your veterinarian by collecting a full history (breed, age, vaccination status, lifestyle of your pet, signs that you have noticed, etc.), performing a complete physical exam, performing a fecal parasite test, a parvo fecal test, and bloodwork (affected individuals often have a low white blood cell count and protein levels). Sometimes radiographs are needed to rule out other causes of vomiting and diarrhea.

HOW IS PARVO TREATED?

Treatment consists of symptomatic and supportive care. The sooner the virus is diagnosed and treated, the better the chances for a full recovery. The goal of treatment is to alleviate the severe dehydration, try to prevent secondary bacterial infections that can occur and provide drugs for vomiting, pain and inflammation.

Hospitalization is the best and most aggressive way to provide treatment for parvovirus. Most patients will need at least 2-4 days in the hospital, while some may require up to 1-2 weeks. Length of treatment will depend on the severity of the disease. Survival rates will depend on age, breed, severity of the disease, immune status of the patient, and whether the patient has a concurrent disease or condition such as distemper or parasites. Survival rates can range from 30-80%.

HOW TO PREVENT PARVO?

Since there is no way to prevent your puppy or dog from being exposed to this virus in the environment, your puppy or dog must be vaccinated. The proper vaccines must be given in the proper manner, at the appropriate intervals, and at the proper ages to be effective. It is not just a matter of how many vaccines were given, but at what age, at what intervals and if the vaccines were handled property to be effective. In addition, there is a difference in the quality and type of vaccines.

The other way that you can help prevent this disease in your young puppy is to restrict his or her exposure to public areas (parks, campgrounds, neighborhoods, pet stores, boarding facilities, etc.) until he or she has been fully vaccinated. There is a series of vaccines given usually about 3 weeks apart with the last parvovirus vaccination given around 14-16 weeks of age. The more susceptible breeds may need additional boosters. Also, only expose your puppy to adult dogs that you know are current on their vaccines. Do not expose him or her to stray dogs or puppies.

CONCLUSION

Parvovirus, unlike some other viruses, is a very "hardy" one that can live in the environment for years. It is still a major threat to dogs and a very common cause of death in puppies. Prevention is the best way to fight this virus. Make sure that your canine companion gets the best veterinary care possible to help prevent this deadly disease.

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