FIELD TECHNIQUES FOR VASECTOMY IN BLACK HOWLER MONKEYS (ALOUATTA PIGRA).

Three adult black howler monkeys (Alouatta pigra) were vasectomized for the purpose of population control. Two different surgical approaches (inguinal and pelvic) were used to vasectomize the animals under general anesthesia. One monkey was vasectomized with a pelvic approach, and the other two monkeys were vasectomized with an inguinal approach. The inguinal approach was minimally invasive and proved to be an effective field procedure, utilizing minimal surgical equipment with a mean operative time of 35 min. The inguinal approach allowed for better visualization of the spermatic cord, which prompted easier ligation and transection of the ductus deferens. Identification of the ductus deferens was successfully performed intraoperatively using a tuberculin syringe to aseptically aspirate cord contents, as histopathology was not available. All howler monkeys fully recovered without complication. The social hierarchy of the troop and mating behavior has not been affected. There have been no new pregnancies reported in the troop since the vasectomies were performed. The inguinal approach is preferred as it is minimally invasive and can be performed confidently in a field setting.