[1] Cases tend to fit three clinical syndromes: chronic mild/moderate tracheobronchitis of prolonged duration (6+ weeks),[4] with coughing, sneezing, and watery eyes; chronic pneumonia that is minimally responsive to antimicrobials, possibly including dyspnea; and, rarely, acute pneumonia that rapidly becomes severe and can lead to death.
[6] Diagnosis should rule out known forms of canine infectious respiratory disease complex (CIRDC; also known as kennel cough).
aCIRDC does not respond to regular treatment protocols for CIRCD and the course of the disease is longer and more severe.
[citation needed] The Veterinary Diagnostic Laboratory at the University of New Hampshire have put forth a possible bacterium as the cause.
This could be due to changes in human behaviour following the end of COVID-19 lockdowns and other COVID-19-related disruption to veterinary care (e.g. frequency of vaccination), as well as to the general increase in dog numbers in the US.