Per Christina Clark at the CWRA (CT Wildlife Rehabilitator Association) conference April 12, 2014:

Bordatella comes on FAST and kills FAST; within 8 hours, sometimes. Symptoms can be watery, bloody discharge from the nose that we would often interpret as injury from a fall, but it doesn't stop. Bordatella has several forms and is species-specific; in dogs it is kennel cough and usually does not kill. In squirrels it can come on suddenly and if doxycycline is not administered immediately the squirrel can die before the day is over.