sentences:  In domestic dogs, while the acute generalized form of distemper has a high mortality rate, disease duration and severity depends mainly on the animal's age and immune status and virulence of the infecting strain of the virus.Despite extensive vaccination in many regions, it remains a major disease of dogs, and was the leading cause of infectious disease death in dogs, prior to a vaccine becoming available.The origin of the word "distemper" is from the Middle English "distemperen", meaning to upset the balance of the humors, which is from the Old French "destemprer", meaning to disturb, which is from the Vulgar Latin "distemperare"