Water cooling pads only need to be filled with cold water before using them, and ice cooling pads simply need to spend time in the freezer first. However, gel cooling pads are a little trickier to gauge, but it's still fairly simple. It takes about 10 to 20 minutes for a gel pad to "recharge" once it's exhausted its cooling capabilities and your dog has moved from it. After this time, it should have radiated the absorbed heat back into your surroundings and will be ready to cool down your pooch again.