A - A Horse that his/her back instead of Desensitizing it has been Sensitized by Human because of some kind of damage to his/her back in his/her life in the past , it can be cured but needs Patient Trainer , Time and No Riding to Desensitizing the Back.
How old is the damage and what kind of damage is a big factor also.
Cold Back in Horses has its own Definition and mostly about the Horses Gear some time in the past the gear has hurt the Horses back and it has left without treatment during time and nobody cared therefore gradually the Horse becomes Cold Back.
Cold Back Horse and their reflection:
The term refers to the flinching behavior of a horse when a saddle is placed on his/her back. Horse may sink or arch his/her back when seeing saddle,being saddled or mounted and in some cases can pull back or try to sit down to avoid being mounted.
The most important MUSCLE which plays a big role in Cold Back is LATISSIMUS DORSI MUSCLE.
When you go to their stable without any saddle or any kind of Horse Gear the Horse stands normally and no reaction but when you go with just a saddle PAD they react and the SPINE CURVES INSIDE and the Tail to the Loin comes up, the neck comes up or to one side mostly to the side where the object (saddle pad or the saddle) in our hand is approaching and the Back curves and goes down. This is the reaction of a Cold Back Horse. They horse knows to react to what objects because they know this object will be on their back the.
I always recommend to warm up your horse with the saddle on and readjust the saddle and the girth once more when your horse and the saddle is warmed on the back of the horse,always one open hand should go under the girth where the girth attaches the saddle.
Always before mounting stretch the hand from the front,just stand next to your horse,pick up the hand and stretch it from the front,your hand on the knee and the other hand under the fetlock.
Horse did not know you want to put the Poor child on his/her back thats why did not react at first but it was a dangerous thing to do I am glad that the child is OK.
Always be careful,