Canine embryos are scarce biological material, due to the inefficiency of superovulation and cycle induction/synchronisation protocols. Difficulties encountered in collecting in vivo produced embryos and the impossibility to date to produce canine embryo sin vitro are other limiting factors. In vivo produced embryo transfer procedure is not under control, with only six attempts reported in the literature, leading to the birth of 45 puppies. In vitro, the fertilization rate is particularly low (about 10 %) and the incidence of polyspermy particularly high. So far, no puppy has been obtained from an in vitro produced embryo. In contrast, cloning of somatic cells is successfully used since 4 years with the birth of 41 puppies, with an efficiency not so lower to that obtained in other mammalian species. In the same period, canine embryonic stem sells and transgenic cloned dogs have been obtained. Last generation reproductive technologies are thus in advance over in vitro embryo production. The lack of fundamental studies on the specific features of reproductive physiology and developmental biology in the canine species is regrettable in view of the increasing role of dogs in our society and of the current need for new biological models in biomedical technology.
