The effect of different thawing temperatures and durations on post-thaw viability and acrosome integrity of dog sperm after freezing and thawing in cryovials. For viability, spermatozoa were stained with SYBR-14 for live spermatozoa (A) and with propidium iodide for dead spermatozoa (B). Frozen-thawed spermatozoa were stained for acrosome integrity (C) with Pisum sativum agglutinin labeled with FITC and examined under a fluorescent microscope; (i) sperm with an intact acrosomal membrane, and (ii) sperm with a damaged acrosomal membrane. Values are expressed as the mean ± SE.