In non-handicap races, fillies and mares get a weight allowance. 3lbs or 5lbs on the Flat depending on the type of race and 7lbs over jumps and in bumpers.
A horse is deemed to be ‘withdrawn’ when it becomes a
non-runner for any reason during the course of a race meeting. Often a horse
will be withdrawn due to deteriorating ground conditions on a wet day or if it
refuses to enter the stalls. If a horse is withdrawn from a race for which a
betting market has been formed, bookmakers may deduct an amount from winning
bets placed before the time of withdrawal. The amount deducted is based on the
price of the horse at the time of withdrawal.