A hunting dog may be in tremendous physical condition, but if his feet are sore, raw or bleeding, he won't be hunting anything. So it pays to pay attention to your dog's paws.
Some dogs have tough feet and some don't. You'll have a pretty good idea which type of dog you own after a season or two, but even if he has tough feet, you should be prepared to protect them if the conditions warrant.
The terrain the dog is running on makes all the difference in the world. Retrievers, for example, rarely develop foot soreness, because their job description involves swimming, not running (so long as you're not a full-time field waterfowler).
Flushing and pointing breeds operate in a different world. They can and often do run for hours, which can put them at risk for sore feet.
As a general rule, the drier and rockier it is, the more likely your dog is to tear up his pads. That means most of the public land in the western half of the U.S. is suspect.
Can you toughen up a dog's pads before hunting season? Sure. Daily runs on almost any kind of ground will help, as will keeping your dog (at least some of the time) on a concrete kennel run.
There are also commercial pad tougheners that work reasonably well if you follow the instructions and treat your dog's feet at least a couple weeks before a trip.
But the most reliable protection is to buy dog boots.
There are many different varieties, all of which have their boosters. One of the simplest and cheapest is a motorcycle or mountain bike inner tube, cut to fit. Whatever you choose, buy an extra set, because sooner or later your dog will lose a boot and you'll need a spare.
Always tape the boots on. No matter what kind of fastener the boots come with, they'll stay on better and longer if you tape them snugly — not tightly — around the dog's leg. Duct tape works fine.
How can you tell if your dog's feet are sore?
He'll tip-toe around at the end of the hunt. Even if his pads have not yet torn, that's a sure sign that they will if you continue to hunt him. Put on his boots. It will make him vastly more comfortable and that means more hunting for you.