Sounds like it really wasnt happy from the off from the report, sadly shires will probably now be the rottie of the horse world, what a shame, probably had some pain from the sound of it....
Does sound something was wrong. Horses are flight animals and seems the horse was running from whatever was wrong.
I used to drive a Shire horse in a massive French shooting waggonet. We did a Mayors parade once takeing the carnival Queen and her attendants. We got to the end where the carnival was, haveing pics taken, when the amucopter came realy low from behind doing a flypast. Well Joseph panicked and was ready for off. I was trying to hold him and asked if the girls could be helped down trying not to alarm anyone whilst looking to see if there was a direction i could turn his head if we went as the place was packed. Luckily the brake locked on fast and he panicked on spot. People didn't realise he was panicking and just thought he looked like he was doing a display. I was terrified but tried not to show it. We left pretty sharply. The ambucopter came over again whilst we were on the main road and Joseph set off in canter down the main road. My mate was hanging onto her hat and i was makeing out i was in control. I can laugh now but at the time i was terrified someone was going to get badly hurt. I am only 5'2" and weighed 8 stone at the time.
The day started off bad when he stood on my foot in the horse box and i nearly passed out. We were then following the mayor and mayoress in an open topped vintage car going about 1 mile an hour. The mayoress had a hat on covered in flowers and Joseph was after the flowers. He was pulling my arms out trying to stop him. I realy could see him walking up the car and nicking her hat. He was a treasure of a horse, even stopped at red lights and looked both ways at junctions but i think he had a full day of giving me a hard time for the whole time we had him. We do laugh about it now.