While the exact reasons for intentional animal cruelty may vary, nine typologies have been identified by Kellert and Felthous (1985, 1122-1124). In the cases within the animal cruelty database, we see these typologies over and over:

1. to control an animal
2. to retaliate against an animal
3. to retaliate against another person
4. to satisfy a prejudice against a species or breed
5. to express anger through an animal
6. to enhance one's own aggressiveness
7. to shock people for amusement
8. to displace hostility from a person to an animal
9. to perform non-specific sadism

Reference: Kellert, S.R. and A.R. Felthous. 1985. Childhood cruelty to animals among criminals and non-criminals. Human Relations 38:1113-29.