Reproductive Effects of a Long-Acting Deslorelin Implant or Injection in Male African Wild Dogs (Lycaon pictus): A Preliminary Report of the First Seven Months Post-Treatment
Long-acting GnRH analogues have been used for fertility control in domestic12-14 and wildlife species.1-7 However, dosing and efficacy differ between species and individual animals.8-11,13,14 A previously available 6 mg deslorelin implant reversibly contracepts male African wild dogs.2,3
This study examined pre- and post-treatment reproductive parameters of wild dogs administered a 4.7 mg deslorelin implant (Suprelorin®, Peptech Animal Health Pty, Australia; I, n=10), a 9.4 mg deslorelin injection (J, n=11) or a placebo injection (P, n=6). Treatment was administered during the non-breeding season (month 0), and dogs were assessed at months 3, 5, 6, and 7. Parameters evaluated included: serum and fecal testosterone, testicular ([π L × W × W]/6 per a testis) and prostatic (L × W × H) volume, and sperm presence. Data were analyzed with ANOVA.
Post-treatment parameters of injection and placebo groups were similar. The average post-treatment serum testosterone of injection and implant groups differed (I: 0.25 ng/ml, J: 0.63 ng/ml, p≤0.10). However, post-treatment fecal testosterone did not differ between the groups. A significant post-treatment difference in testicular (I: 23.2 ml, J: 36.8 ml, P: 37.6 ml, p≤0.01) and prostatic volumes (I: 4.0 ml, J: 6.2 ml, P: 7.1 ml, p≤0.09) between implant and other groups existed. Of the eight azoospermic dogs, one was azoospermic pre- and post-treatment (1 I), four were azoospermic pre-treatment and three later developed sperm (2 J, 1 I), and three had sperm at treatment but were azoospermic post-treatment (3 I).
Seven months post-treatment, the injection appears ineffective and the implant appears partially effective for male wild dog contraception.
The authors would like to thank the staff of the De Wildt Cheetah and Wildlife Center, Nettie Englebrecht and Hettie Roussow of the Ondersterpoort Physiology Laboratory, Reolf Greyling of the Ondersterpoort Veterinary Institute Virology Laboratory, and Anne-Marie Human of the Onderstepoort Hormone Assay Laboratory for their technical assistance with this study.
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