As a saddle fitter, I see more problems with sore backs etc with horses that are hunted regularly than in any other equestrian field, for the following reasons:
Hunters tend to change shape as the hunting season progresses; they can start the season carrying some summer fat, but the more days they do, the more they become leaner and fitter, and this has an impact upon saddle fit. A saddle that fitted perfectly in October can be too “wide” in December.
Hunting days can be very long and arduous for horses, particularly if they do a whole day galloping and jumping through mud. Some hunters do not develop the correct musculature to carry a rider for that long.
Riders may not be as fit and balanced as they should be – particularly those who do not ride regularly. Hunting gear (jacket, boots etc) is also heavy and can increase the weight that the horse has to carry.
Horses tend to sweat profusely, particularly if they get excited, which can cause irritation in the saddle area.
For all the above reasons I suggest it is good management to have your hunters’ saddles checked regularly so that minor adjustments can be made. If you are buying a saddle for your hunter, please do not expect to be able to buy a second hand one that fits perfectly! It is really important that the saddle is comfortable for both horse and rider, so that you both enjoy a full season