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What Causes Parvo in Dogs?

| Updated September 26, 2017

Infection with canine parvovirus is a highly contagious and potentially fatal condition that requires medical attention. Puppies and unvaccinated adult dogs are most at risk of parvo infection, but all dogs can contract the virus. Keep your dog's vaccines up-to-date for the best defense against infection. Puppies should not be around dogs whose vaccination histories are unknown.

Effects of Canine Parvovirus

Canine parvovirus prevents a dog's intestines from properly absorbing nutrients. Diarrhea and nausea are initial effects. Bacteria normally confined to the gastrointestinal system enter the bloodstream. The dog subsequently loses blood through diarrhea and suffers infection throughout the body. The dog's immune system is also compromised. Parvo is sometimes fatal, particularly in puppies, with death resulting from either dehydration, shock or toxins in the bloodstream.

Transmission of Canine Parvovirus

Parvovirus spreads via contact with infected dogs, contaminated feces or the environment. It lives on surfaces such as food bowls, collars, leashes, kennel surfaces and the hands of people. The virus is hard to kill with normal disinfectants. Dogs hospitalized with parvovirus are normally kept in isolation to prevent spread of the disease.

Signs of Canine Parvovirus

Canine parvovirus presents symptoms such as nausea, vomiting, bloody diarrhea, lethargy, loss of appetite, fever, weakness, depression and dehydration. Puppies with parvo can have very low white blood cell counts. Dogs with canine parvovirus can suffer rapid declines, so prompt veterinary treatment is necessary. There is usually an incubation period of four to six days after exposure to parvo before the onset of symptoms. The American Veterinary Medical Association states that most parvo deaths occur 48 to 72 hours after symptoms appear.

Prevention and Treatment

Protection against canine parvovirus is possible with a vaccine, although different strains of the virus appear in the population and can make vaccinations useless. The AVMA notes that even vaccinated dogs are at-risk for parvo. Since young puppies have not completed their vaccination protocol, be cautious when socializing them with other dogs whose vaccination history is unknown.

Treatment for parvo includes antibiotics, intravenous fluids, control of vomiting and diarrhea and prevention of secondary infections. Without this intervention, parvo is almost always fatal.