horse losing a race

Question
hello sir. today a 6 year old gelding ran in last race racing with 5 year olds and upward. in a field of 11 horses held at 1200m , it finished 8th. assigned weight to the horse was 52.5kgs and the jockey has 3.5kg allowance, so practically, the horse carried 49kgs.

sir, you would be wondering. 3 weeks back, this horse won a race racing with 5 years and upward in a field of 6 horses, with an other jockey with same allowance of 3.5kgs and weight assigned was 60kgs. so, practically, the horse carried 56.5kgs.
another wonder. the distance at which the horse won was 1600m.

thinking logically, the horse had many opportunities to win.
may i know why didnt the horse win?

Answer
hi -- well it could be any number of things that could cause a horse to run a bad race. a different rider, different distance, time between races , track condition, weight difference, also the horse may have had a problem that you didn't notice before he ran the race.  a vet check is always good when you have any questions about why the horse ran a poor race.  thanks ED HESS