(Merck) Chorulon is indicated for the treatment of frequent or constant heat due to cystic ovaries in cows. Chorulon is a freeze-dried preparation of chorionic gonadotropin (HCG). When reconstituted with the accompanying sterile diluent, each 10 ml vial contains 10,000 I.U. chorionic gonadotropin. Typically, the contents of one vial (10 ml) of reconstituted Chorulon are administered as a single deep intramuscular injection. Dosage may be repeated in 14 days if the animal’s behavior or rectal examination of the ovaries indicates the necessity for retreatment. Chorionic gonadotropin.