Dog owners in the state of Michigan are being urged to take steps to protect their animals.

The parvovirus-like disease has killed more than 20 dogs.

Officials in the USA are investigating a mystery illness circulating among dogs in Michigan.

According to The New York Times, the illness has been mostly affecting dogs under two years old and causing parvovirus-like symptoms, such as vomiting, diarrhoea and bloody stools.

The illness was initially reported on Facebook by the Otsego County Animal Shelter in Gaylord, North Michigan, earlier this month.

Shelter director Melissa Fitzgerald said more than 20 dogs in the county had been killed by the illness, some within a few days of showing symptoms.

She added that while vets were still unsure about the cause of the illness, "the best guess” is that it is a new strain of parvovirus. State officials have found some evidence for parvovirus, but Ms Fitzgerald said that when dogs were tested for the disease, the results came back negative.

In light of the reports, the Michigan Department of Agriculture and Rural Development (MDARD) has launched an investigation into the illness in collaboration with local animal control shelters, area veterinarians, and the Michigan State University Veterinary Diagnostic Laboratory.

Michigan's state veterinarian, Dr Nora Wineland, said: “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.”

Dog owners in the state of Michigan are being urged to take steps to protect their animals, including keeping up-to-date with vaccinations and keeping their pets away from other dogs if they are exhibiting any signs of illness.