To dream of participating in bestiality with an animal larger than yourself indicates a feeling of powerlessness within a sexual relationship, and an unconscious desire to dominate a partner whom you believe is more powerful than yourself.
Dreaming of dominating an animal smaller than you may indicate a power imbalance in your intimate relationship that you are not comfortable with.
To dream of watching bestiality and enjoying the experience may indicate a wish to 'tame the wild beast' within yourself. Dreaming of bestiality in any form shows a personal power issue that is on the verge of being resolved.
Additionally, engaging in bestiality in a dream suggests your animal nature and inner desire to release your animalistic tendencies and behaviors. Noticing the size of the animal is important in gauging your feelings of power and domination.
Dreaming of bestiality may also indicate your involvement in an act or situation that you are ashamed of in your waking life.