Hilchos Issurei Mizbeiach 2:5

Concluding the list of the 23 blemishes unique to animals: (19) if an animal has five legs; (20) or three legs; (21) if one of its hooves is round like a donkey’s hoof, even if the animal has split hooves; (22) if one of its hooves wasn’t split, like a donkey’s hoof. This is the kalut of Leviticus 22:23; (23) if the animal’s hooves and the fibrous collagen inside them has withered, even though there’s still some of that collagen adjacent to the flesh.

Hilchos Issurei Mizbeiach 2:6

All of the preceding blemishes disqualify an animal from being brought as an offering. If a consecrated animal develops one of these blemishes, it must be redeemed and it reverts to secular status except for animals that are old, sick or smell bad. The latter three kinds of animals are unsuitable for offerings but may not be redeemed. Rather, they should be kept until they develop another kind of permanent blemish, at which point they may be redeemed. Similarly, if a consecrated animal develops a temporary blemish, it is neither redeemed nor brought as an offering.