Hi Ivan
The way i understand it is that if there are less horses racing then the odd of any horse still in the race change. thus the chance of you placing a winning bet are even greater, so bookmakers re work the odds accordingly.
Here is what the rule says.... see what u make of it.
After a bookmaker has created a book of prices for a horse race, there is every possibility that a horse may be withdrawn (become a non runner) before the race starts. This can happen for many reasons, for example: the ground / going has changed dramatically and it no longer suits a particular horse or simply that a horse has become unwell. As the bookmakers made up the original book based on all the horses taking part, the prices will now be incorrect.
Bookmakers are allowed to make adjustments to prices and this is called a 'Rule 4 Deduction' or R4 for short. Deductions are based on a certain amount of pence in the pound, E.g. 20 pence in the pound and it is the original price of the withdrawn horse which determines the amount of deduction. Rule 4 deductions are applied to both win bets and each way / place bets. It is only your winnings that are affected by the rule 4 deduction and not your original stake. If more than 1 horse is withdrawn, total deductions shall not exceed 75p in the pound.
Rule 4 Deductions |
| Odds of withdrawn horse | Deduction (pence in pound) | % of winnings |
| 3/10 or shorter | | 75p in £ | 75 |
| Over 3/10 | Up to and including 2/5 | 70p in £ | 70 |
| Over 2/5 | Up to and including 8/15 | 65p in £ | 65 |
| Over 8/15 | Up to and including 8/13 | 60p in £ | 60 |
| Over 8/13 | Up to and including 4/5 | 55p in £ | 55 |
| Over 4/5 | Up to and including 20/21 | 50p in £ | 50 |
| Over 20/21 | Up to and including 6/5 | 45p in £ | 45 |
| Over 6/5 | Up to and including 6/4 | 40p in £ | 40 |
| Over 6/4 | Up to and including 7/4 | 35p in £ | 35 |
| Over 7/4 | Up to and including 9/4 | 30p in £ | 30 |
| Over 9/4 | Up to and including 3/1 | 25p in £ | 25 |
| Over 3/1 | Up to and including 4/1 | 20p in £ | 20 |
| Over 4/1 | Up to and including 11/2 | 15p in £ | 15 |
| Over 11/2 | Up to and including 9/1 | 10p in £ | 10 |
| Over 9/1 | Up to and including 14/1 | 5p in £ | 5 |
| Over 14/1 | | No deduction made | |
If there is enough time before the start of the horse race for bookmakers to create a new book, they will do so. In these cases the Rule 4 deductions will only apply to people who placed bets on horses at the original book prices.