I had baseline x-rays from a prior issue, so the vet was able to compare. But for most horses, if the distance exceeded the average, that would be a good indication of laminitis. It also varies by breed.
I thought laminitis was just inflammation of the lamina. What your describing is sinking you’d have to have a pretty serious bout of laminitis to have sinking occur. But i think if i remember right sinking can have a mechanical cause also and not be from laminitis.
It’s been shown that if the distance between the front of the foot and the front of the coffin bone increases (from one baseline to the next image, as opposed to just some variance of average which is where my mind originally was) that is an indication of laminitis, irrespective of founder, and apparently irrespective of “founder rings”.
Sinking cannot happen without laminitis. It just may be so severe and acute that it all happens like twins being born - they are born “at the same time” but one has to happen before the other - laminitis precedes founder.
Being mechanical in origin doesn’t mean it’s not laminitis.
Here’s a good article on it. My gelding was actually hard to diagnose before the x-rays. He was obviously quite foot sore, and didn’t want to walk, but did walk around to eat and drink and did not lie down any more than usual. He also did not react to the hoof testers. We initially thought it was rain combined with a new, rockier, environment as I has just moved him to a new barn. But when it persisted, we did the x-rays. He continued to have minor bouts of soreness after trims until the following fall when the ACTH came back high and we started Prascend. His ACTH at the time of laminitis was well within the normal range even though it was during the seasonal rise.
