With holiday travel approaching, the Department of Agriculture and Rural Development is urging dog owners to be aware of a “mystery illness” that is sweeping the nation.

The illness affects dogs’ respiratory systems, causing an unusual increase in coughing, sneezing, loss of appetite, eye and nasal discharge, fever and lethargy. The disease is untreatable with typical medicines and its exact cause is unknown.

Veterinarians are calling it an atypical canine respiratory disease.

There have been no confirmed cases in Michigan yet, but the disease has been suspected in several dogs with respiratory problems, including one reported in Oakland County by a veterinary clinic.

“With the upcoming holiday travel, it is important for pet owners to ensure their pets are up to date on any vaccinations and work with their veterinarian before traveling,” department communications director Jennifer Holton said.

According to the American Veterinary Medical Association, the infection has been confirmed in at least 14 states, including Indiana, Illinois, California and Florida.

It is highly contagious and associated with canine infectious respiratory disease complex, also known as “kennel cough.”

“These symptoms are similar to other respiratory illnesses in dogs. However, symptoms seem to persist for much longer than others,” Holton said. “What is being reported is the coughing that may persist for weeks to months, and severe forms of the disease can progress to life-threatening pneumonia.”

In a statement, American Veterinary Medical Association President Rena Carlson said there is a low risk of people catching the illness from their dogs.

“However, because we don’t know yet exactly what agent or agents is or are causing the current outbreak, it’s a good idea to thoroughly wash your hands after handling your or other dogs,” Carlson said.

Holton recommended that owners get the latest vaccines for their dogs and monitor them closely. Limiting other illnesses helps dogs recover from the mystery illness.

“It is important to reach out to your veterinarian early on in your animal’s illness so diagnostic testing can be completed and an appropriate course of treatment can begin,” she said.