From the rules:

"...roll the dice [total] them and [move] that horse forward one space. However, if the total on the dice is that of a scratched horse, then [you] must pay the amount which that horse is standing on [to the pot].

Play continues around the table, until one horse reaches the finish line!

Your cards are your shares of each horse in the race. If horse number 9 should win the race, and you have no nines in your hand, then you're just plain out of luck. On the other hand, if you were to have two nines in your hand, you would win half of the pot!"