Assisted reproductive technology in canid species.

Assisted reproductive technologies in dogs began as early as the 18th century. The first scientifically recorded artificial insemination (AI) was performed in Italy by Spallanzani and lead to the birth of three pups. Progress in the area was slow, and subsequent development included AI equipment and methods for short-term preservation of fresh, and later, for frozen semen which led to the world's first litter produced from frozen semen in 1969. Improvement of freezing methods and AI equipment from 1970 onwards has rendered AI useful as a breeding technique for dogs. In parallel, AI in foxes was developed in Scandinavia in the early 1980's; this resulted in the economically valuable crossbreeding of silver and blue foxes for the production of bluefrost pelts. Unfortunately, due to the particular physiology of the canine female, progress in other artificial breeding techniques has lagged behind. Only in the last few years have these techniques been successfully applied in basic research to study oocyte maturation, in vitro fertilization, embryo cryopreservation and embryo transfer in canids.