I agree with Dani here,
saddles are made specifically to allow your horse to move comfortably in the discipline they were designed for. Unless you want your horse to be uncomfortable due to restricted movement, I would either use a jumping saddle or an all purpose saddle which allow freer movement of the horses shoulder and back.
It works just fine to do it, I know a couple of dressage riders that jump with their dressage saddles in training. It's much easier with a jumping saddle, since you don't really get the right position for jumping in a dressage saddle.