Hormone-sparing non-surgical male contraception in dogs and cats: Current strategies and the emerging role of FSH receptor-targeted antibody fragments.
TL;DR
Current non-surgical male contraceptive approaches in dogs and cats are summarized, including GnRH agonists, progestogens, androgens, systemic chemical contraceptive agents, intratesticular and intraepididymal chemical contraceptive agents, therapeutic ultrasonography, gene-editing strategies, and immunological approaches.
Abstract
Surgical reproductive control remains the most widely used method for reproductive control in dogs and cats, but it requires anesthesia, trained personnel, surgical facilities, and post-operative care, which may limit its application in large-scale free-roaming animal populations. In males, orchidectomy also eliminates Leydig cell testosterone production, removes negative feedback on the hypothalamic-pituitary-gonadal axis, and may contribute to persistent elevation of luteinizing hormone. These endocrine changes have increased interest in hormone-sparing contraceptive strategies that suppress fertility without fully reproducing the hormonal consequences of castration. This review summarizes current non-surgical male contraceptive approaches in dogs and cats, including GnRH agonists, progestogens, androgens, systemic chemical contraceptive agents, intratesticular and intraepididymal chemical contraceptive agents, therapeutic ultrasonography, gene-editing strategies, and immunological approaches. Many existing methods suppress the hypothalamic-pituitary-gonadal axis, damage testicular tissue, require repeated administration, or have inconsistent effects on testosterone preservation. In contrast, follicle-stimulating hormone receptor (FSHr)-targeted antibody fragments offer a more selective approach by targeting Sertoli cell support of spermatogenesis while avoiding direct interference with LH-mediated Leydig cell testosterone production. Recent studies in dogs and cats have demonstrated species-specific anti-FSHr antibody fragments that suppress Sertoli cell functional markers in vitro, while in vivo evidence from long-tailed macaques suggests that anti-FSHr scFv can impair sperm output and semen quality without significantly altering serum testosterone concentrations. Although further in vivo studies are required in dogs and cats, anti-FSHr antibody fragments represent a promising emerging direction for hormone-sparing male contraception in companion animals.
