Complex sentence: At breaking-in, Holy Roller measured 17 hands and weighed an estimated 660 kgs; each time he went out for a spell, on his return he would be re-measured and always have increased in height.
Split into simpler sentences: At breaking-in, Holy Roller measured 17 hands and weighed an estimated 660 kgs. Each time he went out for a spell, on his return, he would be re-measured and always had increased in height.