Carthage scored six unanswered goals in the first quarter and added two in the second before Southwestern got on the scoreboard. Everett Barger scored unassisted with just over four minutes remaining in the half.
Southwestern went into the break trailing 8-1 and fell behind even further at the start of the second half as Carthage posted two goals in the third quarter to go up 10-1.
The Pirates opened the fourth quarter with a goal from Matthew Montagne to bring Southwestern within 10-2, but Carthage answered five minutes later to go up by eight again.
The Pirates trailed 33-23 in shots and 55-17 in ground balls while committing 14 turnovers. Charlie Fishers recorded 11 saves on the afternoon.
Now 1-2 on the season, Southwestern returns to the road next week to face Millsaps College in Jackson, MS on Friday at 7 p.m.