Take action - we are fostering two new dogs who'd just boarded at an infected vet clinic. They started coughing (gag-reflex coughing) 5 days ago, we separated them from our other five dogs, and have disinfected multiple times per day...and at 2AM, one of our original pack started. It's highly contagious - be a good friend to your best friend and take action (vaccinate, or don't board/expose to other dogs).