:( terrible Christena! I am so sorry to hear that! Hope this teaches that "professional" NOT to single long line again :( I guess this kind of people just have to learn that way... poor horse :'(

Yea it sucks. He was such a beautiful animal had a great life a head of him. I will be speaking with the stable owner on Monday and showing them some of UNI videos and asking them to please consider only using this type of training at the stables.

I've actually had a couple bad experiences two-line long lining. My horse was acting up while long-lining, and other people were in the riding arena with us. She kept bolting, and I lost control several times as she tore the lines from my hands.

This isn't her fault, but it was a dangerous & scary situation, not to mention the other boarders were pretty mad at me. For this reason, I can totally understand why people single-ling lunge so much. It's easy to do, it's easy to understand (for the human), and the human has more control over the horse in a 'safe' circumference.

Now of course I'm not advocating single-ling lunging, but I think some people are ignorant and lazy, and can't be bothered to learn a better way until something horrible has to happen. Hopefully this tragedy will be a lesson for those at your barn.

Well, first of all I don't double line longe except once in a while. Some people that double longe still force the horse to the end and end up still forcing the horse "off symmetry" by keeping the inside line way to taught. I use a single, however, I don't make the horse go to the end of the line either which is what forces them "off symmetry" (so to speak)and causes this life long damage.
Just train them to learn that they simply do not have to go to the end of the line is all. Eventually and very quickly you longe line with a loose "neck only" rope. You might want to tell the trainer to try that?...most don't listen, the saying that I find applies a lot is..."please don't confuse me with the fact, my mind is already made up".
Not to pick sides here, but, there is a very real probability based on averages that the the stumble was simply the final precipitating factor that ended up "breaking the camel's back". Horses legs bones are capable of withstanding literally thousands of pounds of direct stress.
However, thousands of horses a year are diagnosed with stress fractures which over time on many occasions end up as compound, mostly with thoroughbreds. Virtually all of these are caused by hard-nosed, "don't give a damn" trainers. I don't want to appear unduly critical here, but if this chap is the only trainer that this horse has had for the last few months or couple of years, then he could be directly responsible for this. Most trainers (not all) but way too many trainers simply train their horses way too hard with results just like this.

Thanks Paul for your input again here. My sentiments are similar - seems like a very unfortunat, horrific accident that could happen to anyone even with two lines. Must have been awful to witness it. I have tried two line lunging successfully but find it awkward and potentially dangerous when inexperienced with the technique. Safe enough in a round pen but I would prefer a single lunge if I have to handle a flighty, spooky horse in a paddock situation eg Cash - half the chance of getting tangled in a lunge line! I single line lunge with a loose rein and no whip on a rope halter or the dually - I think this way I avoid the body pressures that Monty condemns