A Study of An Immunological Contraception Method for Dogs Using GnRH

2001 Fiscal Year Final Research Report Summary

• Project/Area Number: 09460147
• Research Category: Grant-in-Aid for Scientific Research (B).
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: Applied veterinary science
• Research Institution: Nippon Veterinary and Animal Science University
• Principal Investigator: TSUTSUI Toshihiko Nippon Veterinary and Animal Science University, Department of Veterinary and Animal Science, Professor, 獣医畜産学部, 教授 (40060529)
• Co-Investigator(Kenkyū-buntansha): HORI Tatsuya Nippon Veterinary and Animal Science University, Department of Veterinary and Animal Science, Assistant, 獣医畜産学部, 助手 (80277665) ; KAWAKAMI Eiichi Nippon Veterinary and Animal Science University, Department of Veterinary and Animal Science, Assistant Professor, 獣医畜産学部, 助教授 (80139352)
• Project Period (FY): 1997 – 1999
• Keywords: canine / contraception / anti-GnRH / ovary / testis

Research Abstract

In place of permanent contraception by excision of the gonadal glands, a new immunological contraception method using GnRH for dogs was investigated. I. Twenty beagles aged 1-7 years were used in the experiment. After administration of GnRH-KLH, the time-course blood anti-GnRH antibody titer, LH level, and progesterone (P_4) level, and state of estrus were observed. After a single dose of GnRH-KLH, the time-course anti-GnRH antibody titer was kept at a low level and estrus was not inhibited. After two administrations, although there were individual differences, the anti-GnRH antibody titer obviously increased and persisted for 11 weeks on average. In dogs with a high anti-GnRH antibody titer, LH secretion was strongly inhibited. LH secretion recovered as the anti-GnRH antibody titer decreased and estrus returned. II. Twelve beagles aged 2-3 years were used in the experiment. The blood anti-GnRH antibody titer, LH level, and testosterone (T) level, and the size of the testis and semen properties were observed after administration. While the anti-GnRH antibody titer did not increase in the control dogs, the titer rapidly increased after the booster in the GnRH-KLH treatment group and secretion of LH and T was inhibited as the antibody titer increased, resulting in atrophy of the testis and a decrease in the number of sperm cells. Azoospermia developed and persisted for 4-15 weeks, 10.4±1.9 (SE) weeks on average, in five treated animals (55.6 %). This finding suggests that an increase in the dose of GnRH-KLH may maintain the anti-GnRH antibody titer at a higher level. Spermatogenesis recovered as the anti-GnRH antibody titer decreased.
To maintain the contraceptive period, a booster administration may be necessary. Contraception may be obtained in female dogs by active immunization with GnRH.