In general, the horse must be large enough that your legs don’t dangle to the fetlocks, but small enough that you can mount unaided, and not so wide that you can’t wrap your legs around it. Whether or not your horse is finding it hard to cope with your own size depends on more factors than just your weight and/or height. For example, what type of discipline are you and your horse taking part in?

If you plan to show, consult a trainer or instructor in your discipline to see if your size is well suited to your horse for the particular discipline. If there are any signs of injury or tenderness to the feet or back, this may be an indicator of weight incompatibility, and your vet’s suggestions as to the cause of such discomfort will lead you to the answer. Likewise if her conformation is suffering a vet will need to access her weight bearing ability.