Approximately by what decade did the breeding of the Dual type English Springer Spaniel begin to fade due to specialization?

Answer

The 1940s

In the earlier history of the recognized English Springer Spaniel breed, particularly following its official split from the Cocker Spaniel in 1902, dogs were often bred as 'Dual type.' These dual-purpose dogs were expected to possess both the structural soundness and competitive conformation required for show rings, alongside the necessary drive and soundness for physically demanding days spent in the field trials. However, the text indicates that by the 1940s, this duality started to disappear. Breeders increasingly elected to focus intentionally on specialization, leading to the clear division between the Show Line and Field Line seen today, as achieving high performance in both venues simultaneously became too difficult.

Approximately by what decade did the breeding of the Dual type English Springer Spaniel begin to fade due to specialization?
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