Canine parvovirus is the most common serious infectious disease of dogs in the United States. Canine parvovirus causes ulcerative enteritis and diarrhea in susceptible dogs. This diarrhea can be bloody and life-threatening. The parvovirus has mutated several times since 1980. The most common strain today is CPV-2B. Parvovirus is an extremely tough and resistant bug. The virus lives for long periods of time on floors, food containers, and other household objects.


Parvovirus disease is remarkable in that symptoms can vary from none to all to a fatal disease. Four factors govern the severity of the disease: age at exposure, the size of the virus dose, the presence of maternal antibodies, and the breed of the dog involved. Dogs receive transient maternal antibodies from their mothers through their first milk or colostrum. This antibody gives the puppy resistance to the disease. Puppies that are housed in a parvo-filled environment rarely break with the disease until they reach

14-20 weeks of age. At that time their mother’s immunity no longer protects them and they may die of the disease. Dogs over six months of age develop natural resistance to the effects of parvovirus. Many of these dogs show only transient diarrhea. The most common form of parvovirus infection is a sudden (acute) inflammation of the small intestine or enteritis. This is characterized by depression, vomiting, diarrhea, and profound dehydration.


Treatment of parvovirus is directed at correcting the life-threatening dehydration that accompanies diarrhea with intravenous fluids. Once the initial dehydration is corrected, maintenance fluids can also be given subcutaneously. Many of the younger dogs have hookworm infestations that make the parvovirus disease more severe. As soon as these dogs can hold down liquids, they are wormed with pyrantel pamoate.

Dogs and puppies that begin to accept small portions of food invariably are on the road to recovery.


Recovered dogs are probably immune for life. Because of the strong immunity that follows an infection, carrier dogs do not exist. Many excellent brands of vaccines are on the market. Most contain living, attenuated (weakened) parvovirus. All products are safe and produce good immunity when the last injection is given at 16 weeks of age. When a vaccine fails it is usually because it was given to a puppy before enough passive maternal antibodies were gone from its bloodstream. Parvovirus is still a major threat to dogs in the United States and a common cause of mortality in puppies. Due to the resistance of the virus to antiseptics, heat, and drying, it is impossible for a kennel to be 100% safe from this disease. No matter what puppy vaccination schedule is used, there will be a window of susceptibility when puppies are at risk of disease if exposure occurs. Rapid veterinary care can save many infected dogs, but some will die from the disease despite excellent care.