I don’t own Boxers, have never even met one, but I do know that they’re classic goofballs, children in fur coats. That Boxer probably saw the horses and wanted to play, go check it out. Since the owner called out and asked if the horse was okay with barking, it sounds to me that she knew her dog(s) were excitable around horses. That Boxer was probably the barker in the past. The OP didn’t mention if any of the dogs barked, just that the Boxer bolted. Now, I will agree that any kind of leash attached to velcro with a strong dog at the end of it, that’s just asking for trouble. I have a reliable dog and I would never attach his leash to velcro. All it takes is one jerk on the leash because he caught sight of a rabbit, and I won’t be able to catch the leash in time. Most likely, the end of the leash will slip just past my fingers as my hand clenches over it. His leash is always looped in my hand, with the loop actually over my thumb (seriously, try it. The thumb is a STRONG anchor).
Personally, I love Flexis, but they’re only great with owners who have common sense. And I just want to point out that the BRAND of Flexi is great; other knockoff brands seem to be the weak ones that break. I’ve owned two Flexis, and one retractable leash that was not the Flexi brand and that was the only one that was junk. Seriously, it broke the day it arrived (I ordered it off ebay). It wouldn’t retract very well at all; I would stand there manually pushing 20’ of string back into the handle, while Jake was sitting there next to me watching. And while growing up, Jake has had his share of bolting and I’ve never had a problem with the Flexi. I’ve had the handle yanked out of my hand, and that was always because I wasn’t paying attention. Jake’s first Flexi (the one during his training years) suffered a lot of abuse, from a teething Jake, to being dragged through mud, sand, puddles, snow, dragged over concrete or ice. Being stepped on by a human foot stop the dragging, or dropped from a high distance (without the dog attached to it, lol), or left outside in the rain or snow. It lasted a good 6 years without any mechanical issues (though the thumb button was a bit morphed from tooth marks and was slightly “sticky”). It finally died when the string snapped at a weak spot when Jake decided to play tag with a Bouvier through a fence. Then I got the junk retractable (and instead used it as a cat leash), then spent a couple of years with just the ordinary leashes before I finally got a new red one. It’s still going great, but then again, Jake’s all grown up, well-trained, and the leash doesn’t have the chance to be abused anymore.
Another thing, many people have voiced experiences with horses who had one issue with something, and continued to be troublesome with the same thing afterwards. That brings up the fact that the Boxer was just sniffing the horse, getting to see it up close (I have no doubt that he’s only seen the horses from afar). When suddenly he gets a whack with a whip. Dogs are just like horses in that a bad experience can change them for the future. Who’s the say that from now on, that same Boxer won’t get aggressive to future horses? He’s now experienced pain that came out of nowhere and appeared to have no reason attached to it (now, if the horse was moving, he might link that to the pain, but from what I read, the horse was standing calmly, doing nothing). Now, when he sees horses, he’s going to associate them with the surprise pain, and I’ll bet that he’s going to be a barky mess when he sees them. Wouldn’t surprise me, either, if he lunges at the horses as they pass. Of course, it could go the opposite way: Boxer sees horses in the distance, and wants to turn tail and run. Then, as the horses are getting closer, the owner of the 3 dogs is having greater and greater difficulty getting the panicking dog to calm down, which is lowering her control of the other 2 dogs.
Now, if my dog did something that put someone else in danger, I would definitely work on it myself. He’s seen horses only a handful of times in his life (barking and howling at them through a fence, but once he saw me stroking one’s face, he got closer to sniff it, and calmed right down and ignored them), so if I saw horses coming towards me, I’d immediately go on the alert and do whatever is needed to keep Jake calm and at the same time, let him learn from the experience. If an accident happens that made me lose my grip on the leash (on a trail, lets say my footing slips over rocks or a hole in the ground), and Jake bolted towards the horses, then I would NOT want anyone else to take it upon themselves to train him for me. Those riders are strangers, he’s not going to gain any benefit from them. He needs ME, the pack leader, the teacher, the one he knows and respects, to show him what’s what. Jake is a herding dog, so I already can tell you that he would appear aggressive, circling back and forth by or around the horses, howling. What you don’t see is that he’s actually too afraid to go anywhere near the horses, so trust me, you’re completely safe. The horses are at a greater risk, at that point, to turn tail and run, and for that I’d accept full responsibility and apologize until I’m blue in the face, but accidents happen. If you let anger take over and smack my dog, I’m going to get angry as well and I’m no longer thinking as the owner who made a mistake. I’m now thinking as an enraged owner who watched some moron touch property that isn’t hers to touch and possibly damage it (Jake’s a sensitive guy; I have to tailor his training to meet with the specific way his brain is wired)
Absolutely no one, owner or otherwise, should even THINK about training a dog while angry. There’s nothing more stupid than disciplining a dog through anger. Always have a sense of calm or else there’s the risk that you’re making a huge mistake that’s going to mess that dog up. Another big reason the OP shouldn’t have touched the dog. If he had to be disciplined, she should have waited for the owner to reach them so she could do it herself. If the owner felt that the situation didn’t warrant discipline, then that’s her prerogative, just like it’s the rider’s prerogative whether or not she decides to scold the horse for freaking. It’s her dog, her “property,” and it’s not anyone else’s right to decide what to do with him.
But since its a big tough mean horse, then it’s ok.