For passengers flying with their pets on American Airlines, there is a standard carry-on fee of $125 per pet carrier. The fee applies to each segment of your journey, so if you have connecting flights, additional charges may occur. American Airlines has specific rules about the type of pets allowed in the cabin, usually limited to small dogs and cats. The pet must fit in an airline-approved carrier that fits under the seat in front of you. The pet fee ensures that your pet can travel comfortably and safely alongside you in the cabin.