When I fed this morning, Joe was very slow to move around his stall to get to his hay and grain. He often is very stiff in his hind end in the morning, but this seemed worse than normal. When I went to turn him out, instead of coming to the stall door, he stood with his head in the corner and pawed. I checked him over, and noticed that he had a large swelling on the lowest point of his belly, just in front of his sheath. His sheath wasn't swollen. The swelling was very sensitive to the touch. Just as I was calling his owner, she came to the barn - her farrier was coming. She called the vet - they said it was likely a reaction to insect bites and any swelling had come to rest at the lowest point. We turned him out in a small grass paddock, and he seemed happy to eat. This evening, the swelling wasn't that much smaller, but had spread out a bit and so was less sensitive. We'll see how he is tomorrow. Joe's owner has done a much more detailed post about him at Buckskin and Bay.
Blackjack has gradually been losing some of his mobility. His hind end is getting a bit weak, and a couple of weeks ago he fell to his knees as he was being led in by his owner - he either hit his jaw on the ground or bit his lip, because his lower lip bled quite a bit. This morning he was a bit slow to walk out, and tripped and fell to his knees again. It took him a moment to regain his feet. No damage done - his knees were OK and his head didn't hit the ground. His hindquarter weakness is making it harder to get around. He's eating well, though, and seems happy, so we'll just have to keep an eye on him.