Douglas County, Your vet is probably correct. Horses are very social animals. They often do not recognize the rider's presence and only react to the horse. They will try to interact including establishing dominance, playing, and trying to breed. Its important that you make your presence known with noise and motion when approaching a groups of horses, but that does not solve all. Horses will try to kick at each other, bite etc to establish relationships. Much of their cues are based on hormones and smells that you may not be aware of. Even when experienced horse wranglers move groups of horses they have to be cautious. I had a mare spin and kick at my saddle horse (who pivoted away) and my shin caught the kick breaking my tib/fib. Also since you are controlling your mount they may not be able to react in a way that avoids negative consequences. Some novices feel that horse wranglers are to loud and aggressive when moving horses, but they are simply establishing dominance and awareness by the group to avoid injuries. A good example is the fact the pickup horses at rodeos are equipped with padded chest collars and many of the riders wear padded chaps. Watch how free horses interact with each other and realize what you would be in the middle of. The less familiar your horse is with the others - the more unknowns, but even familiar animals can interact in surprising ways. We review these concepts with trail ride participants and ask that all horses who tend to kick have a ribbon placed in their tail as a warning to following riders. Life in "the herd" can be tough sometimes - realize that when your headed in. BTW the CSU Extension, the Colorado Horse Council and the Colorado Horse Authority all have access to horse safety information. Consider calling the Douglas County CSU Extension office and ask for Horse Safety and Trail Ride Safety information.

Thank you Scott for your answer. I am hoping that you can recommend an equine trainer or vet that I might be able to ask more in depth questions pertaining to equine behavior. Thank you

The two I was familiar with have retired near you. I suggest contacting the CSU Extension office for references, the Colorado Horse Council, or the Colorado Horse Authority.