Verdict: chronic laminitis
Our vet and the farrier came up this afternoon. They wanted to look at Jackson's feet together, when the farrier was here to pull the shoes, so we arranged it on our regular scheduled shoeing day. The plan was to repeat x-rays and blood work.
In the morning, Jackson was walking with just a slight gimp so I turned him out in the paddock after grooming him and washing his tail. He soooo loves the paddock and being able to socialize with the others. He spent some time at the water trough -- the water must taste like champagne. The horses prefer it so much over the water in their stalls.
He spent awhile down there at the bottom of the paddock, sniffing the ground and thinking what ever it is that horse's think while they are sniffing the ground "hmmm, remnants of Kalvin's poop I think..."
At lunch time, he trotted up to the run in shed for his hay. Trotted! Off, yes, but still...
Then, the experts arrived. They pulled his shoes, poked and prodded his soles, and looked at his previous x-rays. They glanced at me furtively. I think they were afraid to voice what I already knew in case I fell apart. But then Dr. Thacher remembered that I am a knowledge hound and confirmed that I had read every scholarly article on laminitis I could find. She knew it wouldn't be a surprise.
It was obvious. So obvious that further testing would be throwing money away. His previous x-rays showed the start of rotation. The increase in the distance between the wall of his hoof and the sole, indicated a progression. He stood with his forelegs stretched out slightly in front, the classic laminitis stance.
We left his shoes off. If he can tolerate being barefoot, it will be better for the health of his hooves.
In an odd way, it was a relief to get confirmation of what I believed was going on. I was commended for giving him a forever home and continuing to do what is best for him, despite the "can never be ridden again" diagnosis. I feel less guilty about looking for another horse, too.