Before you decide to board your dog as you head out for the holidays, be aware there is a mystery illness affecting canines across the United States, including in Georgia.

The potentially fatal respiratory illness begins as a cough that can last for weeks, Today first reported. If antibiotics don’t help, your pet can develop severe pneumonia and struggle to breathe. Some dogs have died from the disease.

Idaho resident Wendy Brown told “Good Morning America” her golden retrievers — Bridge, Dooley and Lulu — started showing symptoms earlier this month.

“Dooley started doing kind of this huffing and also seemed to feel quite lethargic,” Brown said, according to ABC News. “Not too long after, Bridge began to exhibit the symptoms. But his were louder, more boisterous. I thought it was his stomach because he made like a retching sound.”

The vet started one dog on a 10-day cycle of the antibiotice doxycycline, but, Brown said, “Today was day 10 and he is not a lot better.”

Lindsey Ganzer, a veterinarian and CEO at North Springs Veterinary Referral Center in Colorado Springs, Colorado, told Today her clinic has seen about 30 dogs with the condition since mid-October.

“It seems to happen very, very quickly — to go from this cough that’s just won’t go away ... and then all of a sudden they develop this pneumonia,” Ganzer said.

According to the Oregon Department of Agriculture, dogs with the illness have coughing that doesn’t get better, sneezing, runny eyes or nose, lethargy, trouble breathing, and do not test positive for common respiratory illnesses.

Experts say the condition is highly contagious, with canines who visit day cares, dog parks, groomers or boarding kennels most at risk.

Cases that match the symptoms of the mystery disease have been reported in:

  • Oregon
  • Colorado
  • New Hampshire and the surrounding Northeast area
  • California
  • Indiana
  • Illinois
  • Washington
  • Idaho
  • Georgia
  • Florida

Ganzer recommends keeping your dog away from other dog, which might be difficult during the holidays.

“I understand that there are circumstances that are unavoidable and that some people have to (board their dogs), but I would not take this lightly,” she said. “If there’s somebody that can even just come to your house and let your dog out, that’s a better option.”