Lueders Imke, Hildebrandt Thomas Bernd, Gray Charles, Botha Stephan, Rich Peter, Niemuller Cheryl
J Zoo Wildl Med. 2014 Sep;45(3):611-9. doi: 10.1638/2013-0233R.1.
The ability to control testosterone concentrations and sperm production is of great interest in both Asian (Elephas maximus) and African (Loxodonta africana) elephants. GnRH vaccination may pose an alternative to surgical castration. This is a case report of a male Asian elephant treated with two commercial GnRH vaccines (Equity and Improvac). Beginning at the age of 7 yr, the male was vaccinated monthly for 6 consecutive months, then every 6 mo and, finally, every 12 to 24 mo over a period of 6 yr. In order to evaluate the GnRH vaccine as a potential method of immunologic castration, behavioral observations, testosterone level analysis, body weights, ultrasound examinations, and semen collection were part of the routine monitoring of this bull (no. 1) and a half-brother (bull 2) who remained untreated and served as control. The results showed a decrease in serum testosterone concentrations after the second booster. Levels stayed continuously below 5.0 ng/ml within the study period. The combined testicle diameter of 9.03 +/- 0.3 cm prior to treatment had decreased to a size of 6.93 +/- 0.19 cm (P < 0.001) when measured 2 yr later. Accessory sex gland fluid content disappeared and penile atrophy was observed. Semen collections yielded no spermatozoa 1 yr after the initial treatment. Bull 1 showed slowed weight gain as compared to bull 2 and, due to its friendly temperament and the absence of musth, remained in free contact. This report documents the GnRH vaccine as a possible noninvasive and inexpensive method for immune-castration.
控制睾酮浓度和精子生成的能力在亚洲象（印度象）和非洲象（非洲草原象）中都备受关注。促性腺激素释放激素（GnRH）疫苗接种可能是手术阉割的一种替代方法。本文报告了一头雄性亚洲象使用两种商用GnRH疫苗（Equity和Improvac）进行治疗的病例。这头雄性大象从7岁开始，连续6个月每月接种一次疫苗，之后每6个月接种一次，最后在6年的时间里每12至24个月接种一次。为了评估GnRH疫苗作为一种潜在的免疫阉割方法，行为观察、睾酮水平分析、体重测量、超声检查和精液采集是对这头公象（1号）及其同父异母兄弟（2号公象，未接受治疗作为对照）进行常规监测的一部分。结果显示，第二次加强免疫后血清睾酮浓度下降。在研究期间，睾酮水平持续低于5.0 ng/ml。治疗前双侧睾丸联合直径为9.03±0.3 cm，2年后测量时降至6.93±0.19 cm（P<0.001）。附属性腺液消失，观察到阴茎萎缩。初次治疗1年后精液采集未发现精子。与2号公象相比，1号公象体重增加缓慢，并且由于其性情温顺且没有狂暴期，一直可以自由接触。本报告证明GnRH疫苗是一种可能的非侵入性且廉价的免疫阉割方法。
