Canine and Feline Epididymal Semen—A Plentiful Source of Gametes

SIMPLE SUMMARY: The epididymis is a source of fertile spermatozoa. For some males, preserving spermatozoa that are stored in the epididymis might be an ultimate attempt for gamete preservation. The quality of epididymal semen is different from ejaculated semen in various animal species. Although assisted reproductive technologies (ART) have been introduced in cats as a tool to preserve valuable genetics of endangered wild felids, epididymal semen cryopreservation is still suboptimal in dogs. Therefore, in this paper, we carried out a review to list the morphological changes of spermatozoa during epididymal transit alongside with the potential that holds in the epididymal semen in dogs and cats. We believe that better comprehension of epididymal semen collection method, quality and freezability may aid in optimizing cryopreservation and enhance different applications of ART. ABSTRACT: Canine and feline epididymal semen provide an additional source of gametes to preserve the genetics of valuable breeding dogs and tomcats, especially for those that fail to ejaculate, need castration as a therapy or die unexpectedly. Moreover, since it is quite common to perform castration of non-breeding dogs and cats, the development of a gene bank of epididymal semen collected after castration would greatly contribute to increase the genetic diversity in dogs and cats. Collection and cryopreservation of epididymal semen necessitates a full understanding of the function of the epididymis and of the characteristics of epididymal spermatozoa as opposed to ejaculated semen. During collection of epididymal semen, specific factors may have a negative effect on epididymal semen quality and freezability. Accordingly, the elimination of these triggers could enhance epididymal semen freezability and consequently positively influence post-thaw semen quality and outcome for different ARTs.