OTSEGO COUNTY, Mich., (WPBN/WGTU) -- A mysterious illness in Otsego County is making dogs sick and in some cases killing them.

Over the past two months, the Otsego County Animal Shelter says a lot of dogs are becoming extremely ill, with more than 20 dying.

“We are still in the early stages of this investigation, but some of the first samples submitted to the Michigan State University Veterinary Diagnostic Laboratory were positive for canine parvovirus. However, there are more results pending and more to be learned,” State Veterinarian Nora Wineland, DVM. “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. 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.”

We're told the dogs getting sick are two-years-old or younger.

"We were called by some citizens in Otsego County, who stated that their dogs were sick, it seemed like Parvo," said Melissa Fitzgerald, the control director of the animal shelter.

"But when they took it to the vet, it tested negative for Parvo," Fitzgerald said. "Within like two days their dog had died. And then we started hearing more and more about dogs that had passed away with the same symptoms."

Symptoms include bloody stool, vomiting and acting lethargic, which are symptoms of Parvo.

But veterinarians say the blood work show that it isn't Parvo.

"It's something that we don't know anything about," Fitzgerald said. "The state veterinarian, MSU, Michigan Department of Agriculture and Rural Development, they've all been contacted. No one knows exactly what this is."

The advice that Fitzgerald has for the community is to get your dogs vaccinated.

"Call a veterinarian and they will tell you exactly what needs to be done as far as vaccinations and when they should be done," Fitzgerald said.

The animal shelter has been in contact with several vets in Gaylord, Traverse City, Grayling, Mancelona and Indian River.

Fitzgerald said that as of now, Otsego County is the only county seeing dogs with this mysterious illness.

A necropsy was done at the Michigan State University Veterinary Diagnostic Laboratory where the tests came back inconclusive.

Fitzgerald also want to stress that you shouldn't bring your dogs to a dog part with a lot of other dogs until they are at least two-years-old to be safe.

MDARD is encouraging all dog owners to take a few simple steps to protect their animals:

• Keep up with routine vaccinations (especially for those living in or traveling with pets to the northern Lower Peninsula) by ensuring dogs/puppies are vaccinated against canine parvovirus, rabies, canine distemper, adenovirus, parainfluenza, and leptospirosis.
• Have dogs/puppies fully vaccinated before interacting with other animals will help to keep them healthy and safe.
• Keep dogs/puppies at home and away from other dogs if they are exhibiting any signs of illness and contact your veterinarian.
• Be sure to clean up after your pet when you’re walking them out in public.