Influence of Breed and Individual Variation in the Quality of Frozen Canine Semen

The present work aims to report the individual and racial difference found in the freezing of canine semen, as well as to analyze the correlation of the parameters of in vitro evaluation of semen before and after freezing. For this, 36 ejaculates were collected of 12 dogs of the Beagle, schnauzer, Doberman and Boxer breeds, by the digital manipulation method and frozen in Tris-Citrate medium containing 6% of glycerol. Semen was evaluated, before and after freezing, on sperm movement through vigor, motility and spermatic index, and on the integrity and viability of the spermatic membrane by hypoosmotic and supravital staining tests. Sperm longevity was estimated in the thawed semen through the thermoresistance test. Individual variation was observed on spermatic index in the thawed semen, but not in the fresh. The parameters of spermatic membrane integrity and viability presented individual variation in both. When the breed variable is considered was not observed significant differences on parameters in the fresh semen, but in the thawed semen significant variations in the integrity and viability of the sperm membrane were observed. Schnauzers had the lowest sperm longevity after thawing. As Doberman and Boxer breeds presented the best freezing results in the in vitro evaluation. Except for the supravital staining test, the parameters studied showed significant correlations between the data collected in the fresh semen and those observed in the thawed semen.