If you call your vet's office, they can direct you to the closest equine hospital. The only reason I'm suggesting this is I remember that when my cat ate 1/2 a box of Heartguard dewormer (for dogs), he was put on an IV flush for 48 hours to help move things quicker through his system. I understand we're talking different drug/different animal, but I just wonder if that would help Thea.
Best,
Liz R.
Best,
Liz R.