April 22, 2025 was the second annual National Parvovirus Awareness Day. This year’s celebration coincided with the launch of a Parvo Tracker and a new treatment for this highly contagious and potentially fatal disease of puppies. I’ll use today’s blogpost to discuss the these updates in parvovirus prevention and treatment.

What is parvovirus?

Parvovirus is literally a “small” virus, deriving its name from the Latin for small—parvus. But this little virus causes big problems. It attacks the intestines, causing severe, bloody diarrhea, vomiting and dehydration. It also attacks the bone marrow leaving infected dogs with dangerously low white blood cell counts (“neutropenia”). Without infection fighting white blood cells, dogs can succumb to secondary infections such as pneumonia or a systemic bacterial infection. Parvovirus evolved from the feline panleukopenia virus, which causes a similar clinical picture in infected cats.

Why are puppies so susceptible to parvovirus?

Puppies are so susceptible to parvovirus because they have not received their full vaccination protocol yet, or worse—they have not received any vaccines at all.

The parvovirus vaccine is considered a “core” vaccine required for all puppies. The American Animal Hospital Vaccination Guidelines recommend puppies receive at least 3 doses of a combination vaccine including parvovirus, between 6 and 16 weeks of age with 2-4 weeks between each dose. The vaccines are administered over a 10-week period to complement the declining effectiveness of the antibodies from the puppy’s mother’s milk. The challenge of vaccination for parvovirus is that we don’t know exactly when the vaccine becomes effective; it is different for each puppy. Thus, the recommendation for at least three doses of vaccine for young puppies is the safest recommendation.

Where can parvovirus be found?

Parvovirus is shed in the vomit and feces of infected dogs and is highly contagious. Parvovirus is a small but mighty virus. It can survive in the environment for over a year under the right conditions. If an infected dog vomits or defecates in the dog park or on the sidewalk, your puppy could contract the virus while out walking. This is why many veterinarians recommend limiting your puppy’s exposure to places where dogs congregate until the vaccination series is complete. The new Parvo Tracker helps pet owners know how common the diagnosis of parvovirus is in their community.

What’s new in parvovirus treatment?

Most recently, a monoclonal antibody against canine parvovirus has become available for use in the United States. In a laboratory study, one-time, intravenous administration of this antibody to puppies with parvovirus was 100% effective at preventing mortality, reducing severity of clinical signs and shortening the duration of fecal viral shedding. When this antibody is administered early in the course of infection or following exposure without active clinical signs, it can improve outcome.

These two developments in the management of canine parvovirus infection will help the families of young puppies protect their new furperson from a life-threatening infection. What a great way to celebrate National Parvovirus Awareness Day.