title: Fertility of bitches in which estrus was prevented with implantations of chlormadinone acetate for four years.
abstract: The recurrence of estrus and fertility after removal of a subcutaneous chlormadinone acetate implant (CMA-I) administered to prevent estrus for 4 years, was investigated in 8 female dogs and the results compared with those for 4 untreated female dogs (control group). The sex hormones present during the estrous cycle were also investigated. There were no significant differences in the estrous cycle after removal of the implant between the CMA-I-treated group and the control group. However, although conception was achieved after mating and no uterine diseases developed in the control group, only 5 (4 dogs, 41.7%) of the 12 cases (6 dogs) in which mating took place at the second to fourth estrus after the removal of CMA-I resulted in pregnancy in the CMA-I-treated group. Furthermore, 6 (75.0%) of the 8 dogs in the CMA-I-treated group developed uterine diseases including pyometra or hydrometra. There were no significant differences in plasma progesterone, LH and prolactin levels between the non-pregnant and pregnant dogs in the CMA-I-treated group or control group. These results suggest that long-term implantation of CMA-I affects fertility after the implant is removed.
authors.affiliation: Department of Reproduction, Nippon Veterinary and Animal Science University, 7-1 Kyonan-cho, 1 chome, Musashino-shi, Tokyo 180-8602, Japan.
authors.forename: Tatsuya
authors.initials: T
authors.lastname: Hori
authors.forename: Kazuyo
authors.initials: K
authors.lastname: Mukai
authors.forename: Kaoru
authors.initials: K
authors.lastname: Komoriya
authors.forename: Noriko
authors.initials: N
authors.lastname: Shimizu
authors.forename: Masanori
authors.initials: M
authors.lastname: Murakoshi
authors.forename: Eiichi
authors.initials: E
authors.lastname: Kawakami
authors.forename: Toshihiko
authors.initials: T
authors.lastname: Tsutsui
mesh_terms: D000818:Animals; D002715:Chlormadinone Acetate / Q000008:administration & dosage / Q000494:pharmacology*; D004285:Dogs / Q000502:physiology*; D004343:Drug Implants / Q000494:pharmacology; D030762:Estrous Cycle / Q000187:drug effects*; D005260:Female; D005298:Fertility / Q000187:drug effects*; D012739:Gonadal Steroid Hormones / Q000097:blood; D011247:Pregnancy
chemical_list: D004343:Drug Implants; D012739:Gonadal Steroid Hormones; D002715:Chlormadinone Acetate