Chemical vasectomy of domestic dogs in the Galapagos islands

A field test of a previously reported technique for chemically vasectomizing male dogs was performed on Floreana Island in the Galapagos Archipelago. Injection of 0.5 ml of a 4.5% aqueous solution of chlorhexidine digluconate into each tail of the epididymides of seven test animals resulted in azoospermic ejaculates by day 35 after treatment. This azoospermia was persistent for the remainder of the test period and through the fourth month after injection. No changes in ejaculate volume or semen pH occurred with the treatment although a slight, transitory swelling of the testes was observed. A large-scale application of this method was initiated in the Galapagos under the authority of the National Park Service and appears to be a practical technique for reproduction control in domestic dog populations.