Contrary to some of the misinformation that is currently on the internet, ice cubes and ice water are good for cooling off your dog. Lots of dogs like to play with or chew up ice cubes, and many dogs will drink more if you add ice cubes to their water bowl.
Using ice cubes is also a great way to give your dog small amounts of water at a time without having to add fresh water to the bowl every half hour or so. Why would yu want to do this? If your dog is over tired, overheated, or has an upset stomach. In all three cases, he may either not drink enough, or he may drink too much at a time and then throw the water right back up… Instead, put a few ice cubes in his water bowl every 15 to 30 minutes (without any water). This will allow him to lap up a few spoonfuls when the ice melts, or he can chew up the ice cubes. Offer a toy dog one ice cube per 30 minutes, a small (cocker spaniel) sized dog 2-3 ice cubes every 30 minutes, a medium dog (Border collie) 2-3 ice cubes every 15 minutes, and a large dog 3-4 ice cubes every 15 minutes. If your dog fits one of the three situations (overtired, overheated, or upset stomach), you should do this for 3-4 hours.
You should not use ice water to cool an overheated dog, as this causes too much chilling of the skin and outer body. Use cool tap water instead. Soak your dog completely and then set up a fan to blow air onto your (soaking wet) dog. You will need to re-wet a shorthaired dog. Dogs can die from heatstroke, so if you think your dog may be overheated, take it’s rectal temperature (a baby rectal thermometer will work if you leave it in place for one full minute). Normal dog temperature is 100 to 102.5; if your dog’s temperature is 103 to 104, and he is acting fine but tired and panting heard, try cooling him off as described above. Check his temperature every 20 minutes until it has come down one full degree. Then let him air dry to finish the cooling process. If your dog’s temperature is over 104, or your dog is staggering, does not respond when you talk to him, cannot move normally, or is having seizures, get him to a 24-hour emergency veternary care facility as quickly as possible. These are (possibly) symptoms of serious heatstroke; they are also symptoms of many other serious medical emergencies.