Pet owners in Michigan struggled with fear after a mysterious illness recently sickened and killed dozens of dogs within the state. But local officials have now identified the culprit behind the harrowing phenomenon.

The Michigan Department of Agriculture and Rural Development announced Friday that canine parvovirus was responsible for the sudden deaths of the pet animals in the area, New York Post reported.

“Canine parvovirus is a severe and highly contagious disease in dogs, but the Michigan Department of Agriculture and Rural Development and veterinary professionals have extensive experience with this virus,” State Veterinarian Nora Wineland said in a statement obtained by the news outlet.

The announcement just comes after one animal shelter in Otsego County reported at least 30 dogs falling ill due to the virus despite initially testing negative for it.

The virus spreads through fecal matter via the oral-fecal route. This means a dog may get infected after ingesting fecal material from an infected dog. The disease is manifested in symptoms such as tiredness, diarrhea and loss of appetite.

Wineland encouraged pet owners to have their canines vaccinated amid a potential outbreak in the area. According to her, those not fully vaccinated are at risk of catching the disease.

“We have a highly effective vaccine available to help protect dogs from the virus. Dogs that are not fully vaccinated against this virus are the most at risk. Dog owners across Michigan must work closely with their veterinarians to ensure their dogs are appropriately vaccinated and given timely boosters to keep their pets safe and healthy,” she explained.

What’s strange about the recent infections is that the dogs tested negative for parvovirus during point-of-care tests performed in shelters and clinics. This prompted Michigan State University Veterinary Diagnostic Laboratory director Kim Dodd to call the situation “complex.”

"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. Screening tests for parvo are done to help guide immediate isolation, disinfection, and treatment protocols," Dodd said, as per ClickOnDetroit.

She continued, "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."

State officials pointed out that pet owners should not worry for themselves because canine parvovirus cannot infect people or other species of domestic animals.