I'll preface by saying that there are multiple methods of training horses to jump, and everyone has their own way. This is simply what I have found to work! Please keep in mind that not all horses are suited for jumping.
In competitions, miniature horses are not permitted to jump until they are three years of age. personally, I wouldn't start jumping them until the age of five. This gives horses the chance to mature mentally and physically. Some horses love to jump, and some hate it- some are good at it and some are terrible. Keep these things in mind, as an unwilling horse will not excel in it's classes. You can teach any horse to jump, but it doesn't mean they will be good at it (believe me, Scottie is terrible)!
Before you can start jumping, you need to start with the basics-poles and ground work. Lots and lots of poles. Miniature horses don't have the benefit of having a rider to control their strides and judge distances. We, as handlers, can do it to some extent, but it is mostly up to the horse. Poles help horses establish their stride, and teach them at what distances take off and landing work for them. first teach them to trot over poles at a consistent speed without hitting them or tripping. Once they can do this well, I suggest setting a cross rail (maybe two inches high) with two poles (set to their appropriate stride) on either side of the jump.
Once your horse has mastered these distances, move onto cavalettis. On the second height, line your cavalettis up like this:
(2 Strides) (4 Strides) (1 Stride) (4 Stides) (2 Strides)
X X X X X X
This will aide the horse's distances even further. You can mix up the cavaletti placement and distances, and mix the heights on them as well.
Once a horse has mastered these exercises, you can move on to jumping heights. The key to teaching your horse to jump higher is to do it slowly. Don't try and teach a horse to jump a 3 foot standard in a day- more like a couple months. Your horse needs to build up muscle gradually. When training your horse to jump, I wouldn't work them for more than 15 minutes. Keep it short and to the point. As your horse learns and becomes more able, you can extend your jumping time a little. Always end on a good note! If your horse has repeatedly refused a jump, lower it to a height they can comfortably and willingly jump, and then call it a day. Sometimes they just don't feel like jumping as high (just like we don't always feel at the top of our game, either). Some days they won't jump as high, or as long, and that's ok! Always reward them afterwards, cool them down, hose of their legs, etc. After a workout with Patrick, I always use Absorbine's Botanical foam on his joints and legs. Teaching your horse to jump just takes time and patience, and a willing horse!
HUNTERS v. JUMPERS
In hunter classes, just like with large horses, the horse (and handler) are judged on fluidity, appearance, and style. Hunters should keep the same gait throughout the course and they should not charge jumps. They may circle once upon entering the ring and once upon exiting, but not during the course. Horses will trot past the judge after the course for a soundness check, and any unsound horse will be disqualified. Horses with three refusals are eliminated, as well.
Additional training exercises when working with a hunter- oriented horse:
In jumper classes, horses are judged on the accumulation of faults gathered in the course. Faults can be accumulated through knock downs, refusals and, in AMHR time. In AMHA, time does not matter, and competitors may walk from jump to jump, if they please. If a horse has a clean round (no faults), they move into a jump off against the other horses who have had clean rounds. Anyone who has another clean round continues to move on until only one horse has a clean round, or the least number of faults. In AMHA, the jumps are raised (up to 6 inches at a time) each round, and can reach a height of 44", and in AMHR the jumps are raised, but the handlers and horses must race against the clock, as well. The team with the fastest time and fewest faults is the winner.
Additional training exercises when working with a jumper-oriented horse:
I hope this helped, and feel free to contact me if you have any additional questions or suggestions. Always keep your horse's health and well being in mind- it's the most important thing! Happy Jumping!