Mysterious illness killing young dogs in Michigan has been identified: Officials

A mysterious illness that killed over a dozen dogs in northern Michigan has been identified, officials said.

The Otsego County Animal Shelter said in a statement Aug. 19 that over 20 dogs in the county had died due to a "parvo-like" illness, a disease that's highly contagious and often deadly in dogs. The shelter's director, Melissa Fitzgerald, released a statement on Aug. 9 saying that most of the dogs who died were less than 2 years old and died within three days of showing symptoms.

On Wednesday, the Michigan Department of Agriculture and Rural Development and the Michigan State University Veterinary Diagnostic Laboratory confirmed that the disease was canine parvovirus.

In their initial tests, Fitzgerald said the tests came back negative for parvovirus, and the "best guess" was that the cause of death was a new strain of the virus.

Officials said the affected dogs did not have a history of complete vaccination.

According to the Otsego County Animal Shelter, the illness is not affecting one breed over another, but appears to be more common in puppies and elderly dogs.

"This situation is complex because although the dogs displayed clinical signs suggestive of parvovirus, they consistently test negative by point-of-care tests performed in clinics and shelters," MSU Veterinary Diagnostic Laboratory Director Kim Dodd said in a statement Wednesday.

"Screening tests for parvo are done to help guide immediate isolation, disinfection, and treatment protocols. While those tests are valuable in the clinical setting, they are not as sensitive as the diagnostic tests we can perform here in the laboratory. We continue to further characterize the virus in hopes of better understanding why those animals were testing negative on screening tests," she added.

"When MDARD first learned of these cases in northern Michigan, we immediately reached out to the veterinarians and animal shelters involved and began our response efforts," Wineland said in a statement on Monday. "Protecting animal and public health is one of the department's key pillars, but it is a team effort. Dog owners need to ensure their pet is up to date on routine vaccinations as it's the first step in keeping your pet healthy."

Jennifer Holton, spokesperson for the Michigan Department of Agriculture and Rural Development, told ABC News that because parvovirus is not a reportable disease, officials are mostly working with anecdotal information.

"Parvo is an incredibly hardy virus," Holton said. "And by that, I mean it can survive various temperatures and all kinds of things."

Holton said it's essential for pet owners to get their dogs vaccinated and alert their veterinarian if they see signs of illness in their dogs.

She added that proper cleanup, to halt the spread of the disease through fecal matter, is also essential, particularly in high capacity areas like shelters, doggy day cares and other animal-friendly places.

While the mystery surrounding the current death rates is concerning, Holton said officials have the investigation under control.

"The word 'panic' has been used a lot; that is certainly not what we're doing here," Holton said. "Prioritizing animal health is one of the key fundamentals of what our animal industry division in this department does on the daily."