Surgical removal of one conceptus from fifteen mares with twin concepti.

A surgical technique for removal of one conceptus from mares with twin concepti more than 35 days of gestational age was evaluated. One conceptus was removed surgically from each of 15 mares carrying twin concepti that were 41 to 65 days of gestational age. As determined by ultrasonography, eight mares had bicornuate and seven mares had unicornuate twin concepti. For maintenance of pregnancy if surgical trauma should cause prostaglandin release and luteolysis, progesterone was administered prophylactically. Flunixin meglumine was administered perioperatively to minimize prostaglandin release. Five mares with bicornuate twin concepti delivered a single viable foal; in one mare the fetus was alive 4 days after surgery when the mare was euthanatized because of a fractured femur. None of the remaining feti in the seven mares with unicornuate twin concepti survived. The poor survival rate of unicornuate twin concepti was attributed to disruption of the remaining chorioallantois during surgery. Thirteen mares have been rebred successfully.

Use of intrauterine devices as a means of contraception in a colony of chimpanzees (Pan troglodytes).

The uncontrolled reproduction of the captive chimpanzee colony at the Primate Centre, CIRMF, Gabon, has led to high neonatal mortality. The only solution meeting ethical, financial, and practical considerations was to attempt reversible physical contraception using intrauterine devices (IUDs). Human IUDs were inserted into 21 females of various ages, parities, and stages of the menstrual cycle. Over a 30-month period, five of the study animals became pregnant. This reduction of conception rate, with minimal side effects, demonstrates the reliability of IUDs for controlling reproduction of chimpanzee colonies.