The first thing you should probably do, is limit his mobility. Bring him in to a stall or smaller pen, if you can, with extra bedding so he has somewhere soft to stand. Try and pinpoint exactly where he's sore. Run your hands down his legs and around his feet and see if you can feel and heat or swelling. If he tripped in a gopher hole and strained or sprained a muscle, try cold hosing his leg. Ice reduces swelling.
If you don't see or feel any swelling, clean out his feet and make sure he doesn't have any big stones or other debris stuck in his hooves. With the end of your hoof pick, press around the bottom of the hoof to see if you can find a sore spot.
If It’s a Stone Bruise…
If the horse has white hooves, you might be able to see bruises, which could be the cause. Simply taking him off the hard ground and in to a softer pen will definitely help him. If not, try adding more cushion to the bottom of his feet. A diaper, maxi pad or a piece of foam cut to the shape of the hooves and secured with vet wrap and duct tape should help. This will also help if you suspect laminitis and possibly navicular.
If It’s an Abscess…
If you see a tiny pin hole, he might have an abscess. If the abscess has been festering in his hoof for a while, you'll probably notice heat and swelling up the leg. There are poultices available at your local tack and feed store as well as farrier supply stores.
One of my clients called me a couple weeks ago to dig out an abscess. I couldn't get there for a couple days, so I suggested a mashed potato mixture. Boil potatoes and mash them up in the hot water with extra salt. Don't use milk. Put it in a diaper while it's still fairly warm and duct tape it to the hoof. The client texted the next morning and said the abscess burst and I didn't need to go out.
If It’s an Issue with Soft Soles or Brittle Hooves…
When you were pressing around the bottom of the horse's hooves, did you notice if they were harder or softer than normal? If they're softer, there are hoof hardeners available, or putting iodine on the soles will also help harden them up a bit. Dry, brittle hooves may cause part of the hoof wall to break off, making the hooves uneven. This could be uncomfortable and add strain up the legs, and possibly in his shoulders or hips.
There are moisturizers available, but canola oil, vegetable oil or baby oil will help too. If there are pieces breaking off that are big enough to cause discomfort, you probably should have called your farrier much sooner. Keep in mind that summer is our busiest time of the year and unfortunately, we can't always get to everyone right away.
Consider First Aid Training
If you're interested in learning more about ways you can help your horse, and not just their hooves, there are first aid courses available world wide. I'm on the board of advisors for Equi-Health Canada. They have lots of really interesting and informative courses for all ages and experience levels. Check them out—they have instructors all over the world.