you can offer a pool if you want but if you have a double-coated breed make sure to dry them completely so that they don't develop hot spots. Make sure that the dog has access to shade and cool water (not ice water) at all times. A raised bed or cot that allows airflow under the body can also help keep them cool.
If the dog is in heat distress, put cool cloths (not cold) on the pads, groin and "arm pits". Don't give a hot dog cold or icy water as this can send the body into shock and can trigger bloat.
Panting doesn't mean that a dog is "hot" however. It's simply the way that they regulate body temperature since they don't sweat.
If you have a double-coated breed, NEVER shave them. Their coat provides sun protection as well as temperature regulation. A shaved dog of these breeds is actually MORE likely to overheat if shaved.