The aims of this study were: 1) to assess the effect of freezing and thawing on dog sperm DNA fragmentation index (sDFI) using the sperm chromatin dispersion test (SCDt); and 2) to determine whether or not the sperm selection by single layer centrifugation (SLC) using Androcoll-C improves sperm DNA longevity in SLC-selected frozen-thawed dog semen samples. Semen samples were collected from 4 dogs using digital manipulation. After collection, ejaculates were pooled and cryopreserved following a standard protocol. Sperm motility and morphology were assessed before freezing and after thawing as a control for the cryopreservation method used. In experiment 1, sDFI was analyzed immediately before freezing and after thawing (baseline values), showing no significant differences between fresh and frozen-thawed semen samples. In experiment 2, frozen-thawed semen samples were processed or not by SLC using Androcoll-C and longevity of DNA were assessed in terms of sDFI after 24h of in vitro incubation at physiological temperature (38°C). The results showed low values of sDFI in SLC-selected semen in comparison to unselected samples. In conclusion, no effect of cryopreservation was observed on baseline values of dog sperm DNA fragmentation. Additionally, SLC-selection using Androcoll-C improved longevity of frozen-thawed sperm DNA assessed by the SCDt.
