Animals can become angry and attack fiercer than they otherwise normally would.

Spells like calm animals end the effect.

Quick Rules: +2 to all attack and damage rolls; +2 hp/HD; +2 to CMB and Fort Saves; -2 to AC, Reflex and Will Saves

Rebuild Rules: Ability Scores +4 to Strength and Constitution; -4 to Dexterity and Wisdom.