Sorry about your hen, but glad that you have a vet for care. With a vent injury, treating at home, I would suggest a daily warm soak just to her vent in watery with mild soap or antiseptic. Then keep her vent injury moist with the antibiotic ointment, vaseline, or cream. Time will tell if she is able to poop or lay eggs normally. Watch for constipation and an egg becoming stuck. Good luck.