Individual ejaculates and pooled dog semen submitted to two treatments of medium exchange were evaluated. Semen was collected from six dogs, as individual ejaculates and pooled semen, diluted in a 1:1 ratio in Tris-Yolk medium, centrifuged at 500g/10min and ressuspended to the final concentration of 50x10(6) sptz/mL. The samples were cooled at rates of 0.26 o C/min between 37 and 16 o C, and 0.08ºC/min from 16 to 8ºC, and then kept in a refrigerator for 14 days. In Treatement 1 medium was exchanged every six days and in Treatment 2 after twelve days. The cooled samples were evaluated every 48 hours for sperm motility using the Sperm Calss Analyser® (SCA), and membrane integrity with hiposmotic swelling test and PI/CFDA stain. Pooled semen was easier to handle, mainly considering the decreased work due to volume. When submitted to medium exchange, pooled semen behaved similarly to individual ejaculates; however, results obtained from individual ejaculates showed differences between treatments, which were not apparent in pooled semen results.
dog; pooled semen; cryopreservation
