Mystery Illness Killing Dogs 2025. A mysterious and potentially fatal respiratory illness in dogs has been reported in several states across the country, as veterinarians continue to search for what may be causing. Laboratories in at least four states are investigating a mysterious respiratory illness in dogs that are presenting similar symptoms to kennel cough but can last much longer,.

A mysterious and potentially fatal respiratory illness in dogs has been reported in several states across the country, as veterinarians continue to search for what may be causing. A mysterious canine illness is spreading throughout the country that can linger for months, cause fever, pneumonia and, in rare cases, death.