Canine fresh and cryopreserved semen evaluation.

There is little doubt that objective assessment of multiple parameters related to the functional and morphological characteristics of spermatozoa, increase the predictability of the fertilizing potential of a semen sample. Conventional microscopic methods for sperm evaluation in combination with the more objective computer-assisted sperm motility and morphology analyzers and flow cytometry, have allowed investigators to obtain precise information about the morphofunctional status of spermatozoa, which already has resulted in a better understanding of sperm biology and of some of the mechanisms involved in sperm cryoinjury. In addition, assays based on in vitro fertilization provide valuable information about the functional ability of spermatozoa when interacting with the oocyte. Although objective methods for dog sperm evaluation are available for many researchers, considerable effort has still to be invested in order to standardize physiological sperm parameters for the results to be interpretable under unified criteria. In the present paper some of the classical and new methods currently used for dog sperm evaluation are reviewed, though not exhaustively, covering some aspects of the sperm cell that are useful in estimating its functional ability.