Within horse racing, for whatever reason, a horse that has been entered into a race may not actually run. If a horse does not run they are declared as a non-runner which will be indicated by “NR” on the race card.
As there are fewer horses running in the race this, in turn, impacts the odds on the remaining horses in the race. Their odds will be reduced and this is known as a Rule 4 and the odds will be reduced by a percentage factor.
The percentage amount, by which the remaining odds are reduced, is dependent on the odds of the horse being withdrawn. If it is a high odds horse then the reduction factor will be low and if it is a low odds horse the reduction factor will be high.
If the horse that is withdrawn has odds of 15.0 or above then there will be no reduction in the odds of the other horses at all.
The level of deduction is outlined in our 'Rules' page but is also shown below:
The table shows the amount of the deductions based on the price of individual selections. These deductions are the amount of money that is taken from each £1 in winnings. If you win £10 and there is a 20p Rule 4, you will receive £8 winnings.