Background: Using cryovial for freezing dog spermatozoa provides a practical method to increase extended sperm volume and shorten the time required for equilibration by using a simple freezing techniques. The purpose of this study was to determine the optimal thawing condition for dog sperm cryopreservation using cryovials. Methods: For sperm freezing, cryovials with 200 × 106 sperm/mL were cooled after the addition of tris egg yolk extender (TEY) at 4℃ for 20 min, then TEY with 4% glycerol was added and equilibrated for another 20 min before being aligned over LN2 vapor for another 20 min and plunged directly into LN2. Spermatozoa were thawed in a water bath at 37℃ for varying times (25 sec, 60 sec, 90 sec, and 120 sec) in the first experiment. In the second experiment, spermatozoa were thawed in a water bath at various temperatures and times (37℃ for 1 min, 37℃ for 1 min with gentle stirring, 24℃ for 24 min, and 75℃ for 20 sec). In these experiments, the effect of thawing conditions on motility parameters, viability (SYBR-14/PI), and acrosome integrity (PSA/ FITC) of spermatozoa were investigated. Results: The post-thaw sperm motility parameters, viability, and acrosome integrity were not significantly different across the experimental groups. Conclusions: In this study, the characteristics of spermatozoa frozen using cryovials were not significantly affected by various thawing conditions.

ABSTRACT
INTRODUCTION
MATERIALS AND METHODS
    Animals
    Semen collection and preparation
    Sperm freezing extenders and freezing procedure
    Thawing procedure
    Post-thaw sperm evaluation
    Statistical analysis
RESULTS
    The effect of the thawing condition at 37℃ fordifferent durations on the sperm motility parameters,and viability
    The effect of the various thawing condition withdifferent thawing temperature on the sperm motilityparameters, viability, and acrosome integrity
DISCUSSION
CONCLUSION
REFERENCES

• Saddah Ibrahim(Laboratory of Theriogenology and Reproductive Biotechnology, College of Veterinary Medicine, Jeonbuk National University, Iksan 54596, Korea, Department of Veterinary Medicine and Surgery, College of Veterinary Medicine, Sudan University of Science and Technology, Khartoum 11111, Sudan)
• Yubyeol Jeon(Laboratory of Theriogenology and Reproductive Biotechnology, College of Veterinary Medicine, Jeonbuk National University, Iksan 54596, Korea)
• Il-Jeoung Yu(Laboratory of Theriogenology and Reproductive Biotechnology, College of Veterinary Medicine, Jeonbuk National University, Iksan 54596, Korea) Corresponding author