Join Date: Feb 2012
Location: South Wales, UK
• Horses: 0
Sounds like it could be collagen necrosis. They tend to be small, hard lumps which are often not painful if palpated. They can sometimes appear almost spontaneously, and resolve just as quickly, but current theory seems to be they may be pressure-related.
It's thought what happens is that a small area of subcutaneous connective tissue dies, through the associated blood supply being disrupted (hence the pressure thing) and this calcifies into a tiny lump. They only become painful if continued pressure is applied, irritating the surrounding tissues.
You often find them at the edge of a saddle panel rather than in the middle (though they appear there too) especially if a new saddle is either larger or smaller than the horse is used to, or if the horse is ridden for a longer period (eg. a horse used to an hour or so's exercise being taken on an all day ride)
There's no real treatment as far as I know apart from not using the horse, using a felt pad with holes over the lumps to remove any pressure, or using a thick pad but reducing the exercise level, all of these depending on the severity of the problem.
The good news is they often resolve over a couple of days (though sometimes not). Most they're just a darned nuisance rather than a serious problem. But you have to keep an eye on them, as you found :(