Preliminary Tests of a New Reversible Male Contraceptive in Bush Dog, Speothos Venaticus: Open‐ended Vasectomy and Microscopic Reversal

Abstract

Open-ended vasectomies were performed on four male bush dogs (Speothos venaticus), with three having microscopic reversal surgery (vasovasostomy) between 10 and 20 mo post-vasectomy. The key to ease of reversal is leaving the distal (testicular) end open to allow leakage, resulting in a pressure-relieving granuloma. The proximal (abdominal) end is cauterized, providing an effective seal. This technique prevents the buildup of pressure in the epididymis, therefore limiting damage to the male's reproductive capacity. Described here are detailed procedures for both surgeries. One of the three males that underwent vasovasostomy has successfully impregnated his female partner. This study demonstrates that these techniques can be successfully applied to animals. With the two remaining pairs, none of the four individuals were proven breeders prior to the study, so it is not possible to eliminate the possibility of previously existing infertility. This technique may have limited application for carnivores, because vasectomy does not prevent potential adverse effects to females from prolonged, cyclic exposure to endogenous progesterone. In other taxonomic groups (e.g., primates, ungulates, marsupials, and rodents) in which multimale groupings are common, this reversible male sterilization technique could provide managers with the ability to control which males reproduce without eliminating their future reproductive capacity or social interaction.

Contraception

“…13,29 Success Although potentially reversible, the technique requires highly skilled microsurgery, but high pregnancy rates have been achieved postreversal.…”

Review of contraception in ungulate species

“…This technique prevents mating, but is perhaps inappropriate for exotic species, especially those exhibited in zoos. One new method that has been applied successfully in humans and wild dogs is the reversible vasectomy [DeMatteo et al, 2005]. Using this technique, the end of the vas deferens is not tied, allowing for potential reversal of the vasectomy using microsurgical techniques.…”

AZA Wildlife Contraception Center Programs

“…A rather different technique, reversible vasectomy, was recently accomplished for the first time in a wild species, the bush dog (Speothos venaticus), a wild canid native to South America (DeMatteo et al 2006). Although this microsurgical approach will not replace the hormonal methods, it does offer an alternative for males, especially in cases where a future need for fertility is unlikely but possible.…”