Lewis Dog Boots are the best, bar none. I have heard of them coming off, but if put on properly, there should be no problem. My dog has never lost one, and he runs big.
Hunt your dog in sand burr country without them, and you've got a 20 minute dog. 20 minutes and then he's down for the count.
Cactus country, lots of lava (chukar country) or sharp rocks, these can really do a number on a dogs feet. The dog may be OK for a day, but try to hunt him the day after. Good boots will let him hunt a long time.
Make sure you get the right size, and if your dog still has his dew claws, a little modification to the bot is in order.
Check out the following site:
http://home.att.net/~wildmandl/lew.htm