ARTs as a tool for overcoming fertility problems in dogs and cats

In human medicine, assisted reproductive techniques (ARTs) are categorize into three levels based on complexity and invasiveness. The physician should select the appropriate procedure, giving priority to the easiest and less invasive technique. In dogs and cats, ARTs aimed at improving reproductive performances and treating male and female infertility, should respect the same guidelines. Thus, in the case of infertility, a careful clinical examination, a diagnosis of the etiology of infertility, and conventional treatments (first-level ARTs) should be attempted before planning more complex procedures (second- and third-level ARTs). First-level ARTs include artificial insemination with fresh or cryopreserved semen, and pharmacological treatments, e.g induction of estrus or ovulation. These ARTs may be applied in cases of impotentia coeundi, primary or secondary anestrus, or ovulation failure. Second-level and third-level ARTs include in vitro embryo production (i.e. in vitro fertilization-embryo transfer \u2013 IVF-ET; intracytoplasmic sperm injection - ICSI), with the use of epididymal or testicular spermatozoa, other than ejaculated spermatozoa, and fresh or cryopreserved oocytes. This review is focused on second- and third-level ARTs that have been developed in dogs and cats