Player's Handbook[]
Proficiency in this area enables a character to exercise a greater-than-normal degree of control over pack animals and beasts of burden. A successful proficiency check indicates that the character has succeeded in calming an excited or agitated animal; in contrast, a character without this proficiency has only a 20% chance of succeeding in the attempt.
Player's Option: Skills & Powers[]
This proficiency allows characters to automatically steer carts, plow horses, etc. With a successful proficiency check, they can soothe domesticated animals and beasts of burden which become agitated or frightened. The characters receive a +1 bonus to proficiency checks made with any of the animal-riding proficiencies, and they receive a +2 bonus to their proficiency rating if they have the animal empathy trait.
Note from The Complete Ranger's Handbook[]
A ranger's animal empathy ability (see Chapter 2) can produce essentially the same calming effect on an animal as the animal handling proficiency. If a ranger also has the animal handling proficiency, he may attempt to soothe an animal either by making a proficiency check or by using his animal empathy ability—but not both.
If an animal is among a ranger's followers, neither animal empathy nor the animal handling proficiency is necessary to control the follower. Use the guidelines in Chapter 3 instead.
The animal handling proficiency has no effect on a ranger's species enemy.
Note from The Complete Paladin's Handbook[]
Animal Handling: As explained in Chapter 2, a paladin can soothe his bonded mount automatically; the Animal Handling proficiency isn't necessary. The proficiency may be used normally to calm other animals of the same species as the bonded mount, as well as other pack animals and beasts of burden.