ewe-necked

from The Collaborative International Dictionary of English v.0.48

Ewe-necked \Ewe"-necked`\ ([=u]"n[e^]kt`), a.
   Having a neck like a ewe; -- said of horses in which the arch
   of the neck is deficient, being somewhat hollowed out.
   --Youwatt.
   [1913 Webster]