This spell causes instant diminution of a single willing Animal, halving its height, length, and width and dividing its weight by 8. This decrease changes the creature's size category to the next smaller one. The target gains a +2 size bonus to Dexterity, a –2 size Penalty to Strength (to a minimum of 1), and a +1 bonus on attack rolls and AC due to its reduced size.

All equipment worn or carried by a Creature is similarly reduced by the spell.

Reduce the Damage dealt by the animal's Natural Attacks as appropriate for its new size (see Equipment to adjust Damage for size). Any reduced item that leaves the reduced creature's possession (including a projectile or thrown weapon) instantly returns to its normal size. This means that thrown Weapons deal their normal Damage (projectiles deal Damage based on the size of the weapon that fired them).

Multiple magical effects that reduce size do not stack.

Reduce animal can be made permanent with a permanency spell.