If a scratch is declared, it means that a selection will not be participating in the event.
The settlement process will depend on the type of bet that you placed.
Straight bets
If your selection is a scratch your bet is deemed no action, and your wager is returned.
Parlays
For bets such as Parlays, if a selection is a scratch, that selection is deemed no action. However, your bet still stands, and is settled on the remaining selections within the parlay.
For example, in a 3 Leg Parlay, if one selection is a scratch, the bet becomes a 2 Leg Parlay.
Important Tip
Futures bets are All in, run or not, so if your selection withdraws, your bet will lose unless otherwise stated.
Rule 4
If another participant other than your selection withdraws from an event, your bet may be subject to a Rule 4 deduction.
The Rule 4 deduction is an industry standard, where a deduction is applied for every 1.00 of your winnings. When odds are offered on an event, they are based on all participants taking part. When a participant withdraws from an event a Rule 4 deduction is applied to all bets placed before this point, to reflect the reduced number of participants running.
You can see any Rule 4 deductions, and the time that it was applied to a market, within an Event coupon.
You can find more details regarding Rule 4 deductions, as well as the deduction table, here.