From what I have heard/read/seen about training horses, it is a lot like training dogs(or anything else for that matter). I have never trained a horse, but I have trained many dogs.
1. First you need to catch them IN THE ACT of performing the undesired
behavior.
2. Then you need to have the ability to modify that behavior IMMEDIATLY.
3. You must be very consistent in the aplication of whatever you use to
modiy the negative behavior(must catch them EVERY time).
4. You must be even MORE consistent and timely with the praise and rewards
as re-enforcement when the correct behavior is exhibited.
Training collars and invisible fencing for dogs are very effective because they provide Immediate behavior adjustment. Electric fences with horses work the same way. I mean you can effectively corral a thousand pounds of animal with a 18 gauge piece of wire that they could break without much effort but they don't unless highly motivated by something else. I do not think a taining collar would be appropriate In the case of a horse, but perhaps a loud unpleasant buzzer or siren in the stall would give you the ability to quickly move the horse outside. Of course the horse must be able to get outside unassisted/unobstructed. If you are able to do this every time, the animal should quickly get the idea that every time she trys to relieve herself in her stall, that loud scary thing goes off, but that never happens when she goes outside and when she goes outside, her master is happy, praises her and she even gets a treat sometimes.
Unless you are prepared to spend a lot of time in the barn to catch the horse every time she starts to relieve herself and shoo her outside, you need some way to automatically detect the act. Perhaps a moisture detector on the stall floor below the chips, sawdust or straw, or a sound activated switch with a mike down low in the stall and set up for a particular frequency of liquid or semi solid splattering on the floor. Anything automatic has to be very selective and timely lest you start correcting her for doing normal allowed behavior or you correct her too late after the deed is done. If the thing goes off for other than the desired reason/time, you will just confuse her. Habitual behavior is also hard to break. You have to be in this for the long haul. If the behavior modification stops, the old behaviors will most likley return. That is probably where the saying "You can't teach an old dog new tricks" came from. Well you can, it just takes more work.
