The days are not so far away when sex sorted preserved liquid semen will be available in drug stores saying "Let me stay cool, I will give you beautiful puppies".To my parents (Abdus Satter and Jamela Khatun ) Preservation of canine semen by extension and chilling has provided the AI veterinarians with an opportunity to overcome limitations of both time and space. Several parameters are assessed to predict the fertility of canine spermatozoa for a given sample. Motility is one of them. Spermatozoa stay immotile while preserved in CLONE (Cryogenetic Laboratories of New England, Inc, USA) Chilled Semen Extender whereas they maintain motility over the whole 23 days period of study while preserved in a Tris egg yolk glucose extender at 5°C.The aim of this study was to investigate whether the immotility induced by the CLONE chilled semen extender prolongs the lifespan of dog spermatozoa stored at 5°C, compared with a Tris-egg yolk-glucose (TG) extender, which maintains motility. Semen from eleven dogs was pooled, split in four aliquots, centrifuged, and the supernatants removed. The four sperm pellets were mixed with a TG extender; with the CLONE chilled semen (CL) extender; with TG extender mixed with TG but without egg yolk and with less glucose (TG+A TG ); or with the CLONE extender mixed with the CLONE activator (CL+A CL ) to a final sperm concentration of 200 x 10 6 spermatozoa / mL. The samples were stored at 5ºC for 23 days and examined twelve times for sperm motility by computer-assisted sperm analysis (CASA), as well as for plasma membrane and acrosome integrity, glucose consumption, and DNA fragmentation index (DFI). The experiment was performed in triplicate. The third replicate was examined for presence of bacteria. For the statistical calculations, the 23 experimental days were divided into three periods, the first period comprising days 1-8, the second period days 9-14, and the third period days 15-23. Total motility (TM%) did not differ between extenders in the first period, but was higher in TG and TG+A TG compared with CL+A CL in the second and third periods, and with CL in the third period (P<0.05). Progressive motility (PM%) was higher in TG (P<0.0001), TG+A TG (P=0.0007) and CL+A CL (P=0.0176) than in CL in the first period. Both TG and TG+A TG maintained higher PM% than did CL and CL+A CL in the second and third period. Tris-egg yolkglucose and TG+A TG maintained higher straight line velocity (VSL) and average path velocity (VAP) compared with CL and CL+A CL during the whole experimental period. Curvilinear velocity (VCL) was higher in TG, CL, and TG+A TG than in CL+A CL samples (P<0.05) in the first and third periods. No differences in lateral head displacement (LHD) were observed between extenders or over time. Acrosome and plasma membrane integrity decreased over time, but there were no differences among the extenders in the first and second periods (P>0.05). In the third period, however, TG, TG+A TG , and CL maintained acrosome and plasma membrane integrity better than CL+A CL . Glucose consu...