Endurance.Net Ridecamp Archives

Hi. I have a friend (I always seem to be writing in about my friends) who has an arab she rides 2-3 times a week. She'll go for about 2-3 hours per day and will do a good workout for about 1 1/2 -2 hrs. of that time. The horse is in pretty decent shape. She has never had this trouble before now and she's owned him for 2 yrs. This last weekend, she took her horse to the Cracked OAATS Crunch ride in the Scioto Forest in Ohio. It was said you should have shoes for this ride because of all the gravel road riding. Well, this friends horse had lost some back shoes some time ago. The farrier was an idiot who didn't call her back so the feet got torn up. So much so that the new farrier couldn't put shoes on him before the ride.  SO, to make a long story short, she did the 25 on Saturday and then the 15 on Sunday. He handled the 25 well but was sore for the 15 of course. 
Well, she rode him a couple of days later at home and thought he was stocking up. She walked him and the swelling came down. She rode today and it was even worse as she rode so she hand walked and it came down again.
My questions are, what causes stocking up? Is it because he didn't have shoes on for this ride? What can you do to make the swelling come down besides walking? Is this an ongoing problem? If it had nothing to do with riding with no shoes on the back, then what can she do to prevent it?
Thank you for your time.

Deb