About 25 years ago I was managing a barn in WI and we got a mare in who was
severely underweight and the owner didn't know when she'd last been
wormed. The vet (who dealt with cows more than horses...remember, this is
25 years ago!) tube-wormed her, and she coliced badly. When she finally
started passing manure, it was mostly worms. So I agree with everyone
else, a strong purge might be too much at first.
