It's the last thing a new pet parent wants to hear from the veterinarian: your puppy has parvovirus.
Parvo, especially in puppies, is an extremely contagious and potentially fatal gastrointestinal illness. Young dogs are most at risk of symptoms associated with parvo because they have not yet been vaccinated against the illness. Parvovirus, also known as B19 virus, is believed to have originated from a similar virus that infects cats and some wild animals (like raccoons and minks) that mutated. The first cases of parvo in puppies was diagnosed in the late 1970s.
Here's all you need to know about this virus and how it can be treated and prevented.
Which Dogs Are Most Likely to Get Parvo?
Puppies aged six weeks to six months are most susceptible, as are any dogs who are unvaccinated or incompletely vaccinated, according to Toronto Veterinary Emergency Clinic veterinarian Kelly D. Mitchell, who wrote about canine parvovirus in the Merck Veterinary Manual. She also said specific breeds are more at risk, including:
Dogs younger than six weeks are generally protected from parvo by antibodies in their mother's milk.

What Are the Signs and Symptoms of Parvo?
If your dog has parvovirus, you will generally start seeing signs three to ten days after exposure. Common signs and symptoms that your puppy may have parvo include:
- Extreme lethargy
- Vomiting
- Diarrhea (usually bloody)
- Fever
Dogs get incredibly dehydrated from symptoms associated with parvo. The virus also can damage a dog's intestinal walls, causing life-threatening issues like a drop in the white blood cell count, sepsis and anemia. It is important that you take your dog to the vet immediately if you suspect he might have parvo. Time is one of the most important factors for survival.