Why do adult Welsh Springer Spaniels often require a higher baseline energy requirement than sedentary breeds of similar size?

Because they were originally bred to perform long days of work in the field

The Welsh Springer Spaniel possesses an inherent energy level derived from its history as a working gundog. This heritage means that even a mature dog kept as a companion often carries a baseline energy requirement that is comparatively higher than many other breeds that share a similar physical size but were not bred for sustained physical output. These dogs were developed specifically to expend significant energy over extended periods, such as working long days in the field or marshlands. Consequently, their dietary needs must reflect this history, requiring owners to account for this elevated baseline requirement when assessing daily caloric intake, even if the dog’s current activity level is moderate.