My horse's hoof is slowly getting a very large red band. She has been lame on and off for about three months now, and most recently, the diagnosis was arthritis. We don't remember seeing this redness growing on her hoof before and wonder if it could be the cause? Is it normal for a hoof to have this? She only has one white hoof, the rest are black. Am I just seeing this because of the color difference in hooves?
You didn't specify where the "red band" was located on the hoof, but you may be referring to the outside rim of the bottom of the horse's hoof. If this is the case, you are probably seeing bruising and inflammation along the "white line" of the hoof, where the sole meets the hoof wall, above which lies the sensitive lamina of the hoof. This symptom is consistent with laminitis, so this horse needs an appointment with the vet to diagnose what may be happening in addition to the previously diagnosed arthritis.
This red band is, in fact, much easier to detect in a white foot versus a dark one, so it is likely that other feet (at least the other front foot) may be affected as well.