Join Date: Mar 2014
Location: South Louisiana
As Loosie stated, I'm guessing that you are somewhat green as a rider/handler still and this boils down to more of a leadership issue than anything else.
I'd address it in two ways. First off, you are dealing with a pattern here and horses can be incredibly specific regarding seemingly minor details that "take them" down a different emotional/mental path. This different path (not wanting to load) seems to be triggered by being away from home. When they take the wrong path it is up to a good leader to not respond emotionally, but to be the rock that keeps them tethered.
I'd start by finishing the next dozen rides by loading up your horse. By this I mean find a good place to stop in your ride and IMMEDIATELY dismount and lead him to the trailer and load him. Once he is loaded and standing quietly in the trailer, loosen the girth and lead him back for untacking. The first time may take 10 minutes. The last time he'll be leading you to the trailer. I try to stay away from the descriptions of positive and negative because of the confusion regarding operant conditioning terms. So, we'll just say that we are forming a pleasant and motivating association with loading in the trailer. Step 1 completed.
Now, we must deal with the problematic trigger of not loading away from home, step 2. I'd pick a day when you have all day. I'd load up ole Thunder and haul him to your vet's office. It can be a Sunday when nobody is there. Let him eat some grass for 5 minutes and load him back up. As in step 1, maybe that takes you 30 minutes this time around. Who cares? You have all day. Next, take him to your local riding arena where shows may be held. Unload. Graze. Load 'em up again. This time it only takes 15 minutes. Next, we go to the grocery store and park far away from the cars. You keep repeating and can even go back and revisit the vet's office and local arena again. Heck go to the vet, unload, reload, then go back to the arena, unload, reload, and just repeat that pattern 4 times. All of this craziness is breaking the old trigger up, dealing with it, and installing a new, more beneficial pattern. It's important each time you load him that you see calming signals from him like licking and chewing, lowering the head, deep breath, etc.
If you take the time to do this a couple of hours a couple of days, I think your loading issues will melt away and you'll have leadership points to burn. I hope that helps.