Kennel cough in dogs typically lasts between 1 to 3 weeks in healthy dogs. In some cases, especially with senior dogs or those with other medical conditions, it can persist for up to 6 weeks. The illness duration can vary depending on whether it is caused by a virus or bacteria, with viral cases usually resolving quicker (around 6 days) and bacterial infections possibly lasting about 10 days. Symptoms may linger even longer if complications or secondary infections like pneumonia develop. Dogs can remain contagious for 2 weeks or longer even after symptoms subside, and isolation during recovery is advised to prevent spread.