KANSAS CITY, Mo. (WDAF) — Parvovirus, which primarily targets puppies, is a growing problem this spring, veterinarians say.

Parvovirus, or parvo, can infect any dog, but it can be especially dangerous – even fatal – for young or unvaccinated dogs. It’s highly contagious, and can spread from dog to dog, or through contaminated feces or surfaces, according to the American Veterinary Medical Association (AMVA). While humans can spread the virus on their hands or clothing, people are immune to parvo’s effects.

Once infected, the virus attacks a dog’s gastrointestinal system.

“Parvo is something you can never tell if they’re going to make it or not,” Rachel Lunsford, an urgent care tech at Pet Resource Center of Kansas City, said.

Veterinarians say dogs often stop eating when they’re first infected, followed by lethargic behavior. Puppies usually show intestinal symptoms, including diarrhea, vomiting and dehydration.

“If you see these symptoms, you need to get treatment for this animal as quickly as you can,” said Tori Fugate of the Kansas City Pet Project.

In spring and summer, parvovirus cases typically rise, writes Colorado State University’s Veterinary Teaching Hospital, because more vulnerable puppies are born. Exposure and transmission also increase as dogs spend more time outside and in parks.

Parvo cases have also been on the rise since the pandemic, according to Sugar River Animal Hospital in New Hampshire, as some pet owners may have fallen behind on or skipped vaccinations altogether during lockdowns.

“We see two to three parvo cases every day. There’s some days where I can see five or six,” Lunsford said. “It’s sad to see sick animals come in.”

Kansas City Pet Project has an isolated parvo ward, since the bug spreads so easily. “It’s taking so much to take care of all these animals. It’s around the clock care they have to get — typically 14-to-18 days for every single animal,” Fugate said on Tuesday.

Vaccines are available, and puppies should receive a dose between 14 and 16 weeks old, the AMVA says. Some owner may find the vaccine too pricey, but low-cost pet centers and nonprofit clinics can make it affordable.

The cost of treating the virus can also be substantial. One veterinarian told Nexstar’s WDAF it can cost as much as $2,000 to care for an unvaccinated pup with parvo. The virus requires immediate care, since an untreated animal can die within a week.

With proper treatment, 90% of dogs recover.