Not likely, Susan-though it is possible there might be one here and there, especially among B sized horses(who* might* be more likely to have some blood from the few larger breeds who actually can be 5 gaited.)Only some of the Icelandics, that I know of, are more or less 'naturally' 5 gaited-Saddlebreds are trained into 5 gaits; there are likely to be more breeds/individual horses, from several breeds, that 'might' be 4 gaited-that is, have the 'square' gaits of walk, trot, lope(or canter)-all of which have evenly cadenced, diagonally-based, beats(footfalls)-and then be able to perform, either through natural tendency and/or being trained/ encouraged into, an 'extra' gait. The 'extra' gaits are usually ones which 'break' the even, and DIAGONAL, cadence of the footfalls in some way, and may be either in addition to, or in the place of, one of the 'square' gaits-usually the walk, or more often, the trot. True pacing has an even cadence, but is a LATERAL gait-that is, first the horse is 'on' the two legs on ONE SIDE of the body, then 'on' the two legs on the other side. There seems actually to be quite a variety of ways in which some horses will perform a 'broken' -meaning not of even cadence-gait--for instance, a couple of friends and I went to MO years ago and got several Fox Trotters-not one of which turned out to do a precise, correct Fox Trot, but instead, variations...in my observation, this seems fairly common in gaited breeds-that what they perform may be comfy to ride, but isn't exactly the 'by definition' gait. One of these horses did a 'stepping pace', for instance. IMO, these tendencies are by and large 'bred into' the breeds who do them-and since minis really have little if any background from those breeds, it would be only the rare individual who might perform any 'extra' gait.
In Standardbreds, "hobbles" are used on the harness tracks to ensure that those entered as pacers 'only' pace; others of the breed are raced at the trot--has to do with each horse's natural tendencies, I think. I have observed both Walkers and Fox Trotters who also have a tendency to be 'pacey'--and imagine there are others, within other breeds, also. Five gaits, though, would presume TWO gaits in addition to walk, trot, and canter---harder to 'come up with.'