When you breed a Racer it will have a rarity attached to it. The rarer the hound then the faster and more successful it will be without training. Rarer hounds can also enter exclusive tournaments with added prize pools. The chances of breeding a Racer of the different rarities are based on the following distribution.
Very Rare: 1.14%
Extremely Rare: 0.13%
All Breeders have the equal potential to breed a Racer of any rarity. For example a common Breeder has the same chance as a rare Breeder to breed an extremely rare Racer.