From: Rabbi Moshe Sofer
To: Rabbi Yaakov Weiler
The goat itself is forbidden, as blood oozing from the neck area triggers the Ashkenazi custom to forbid the animal since the esophagus runs the entire length of the neck. The rest of the flock is permitted because a non-Jew is not believed in matters of issur veheter even when speaking innocently, and the shepherd had a personal motive to blame a wolf rather than admit negligence. The Chasam Sofer also limits the Shach's leniency regarding non-Jewish testimony combined with circumstantial evidence to the bechor context alone, rejecting its application here.
Source: Shu"t Chasam Sofer YD §112