What are the requirements for flying with a service animal on domestic flights in the USA? Are there limits to the size? Is any paperwork needed?

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    The rule that they must not occupy a seat may set a size limit. The Guide Horse Foundation has a photo of a guide horse on a plane. It is a very small horse, but bigger than most dogs. Commented Jun 30, 2017 at 20:46
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    Whether or not it is required, I am sure the horse-owner made advance arrangements with the airline. They have a bulkhead seat where there is room for the horse to stand. Commented Jun 30, 2017 at 21:23

1 Answer 1


Each airlines publishes similar guidelines for those who travel with a service or support animal. In general, they ask for advance notice and appropriate documentation. While the animal's size is not limited, where it is positioned the cabin may be.

As example, Delta Airlines:


We welcome trained service animals in the aircraft cabin. Trained service animals are different from emotional support animals in that they have been trained to perform a particular function or service to assist a passenger with a disability in the management of their disability.

Under most circumstances, we do not require passengers using trained service animals to provide additional documentation. However, it is expected that a service animal behave in public and follow the direction of its owner. In the rare event the animal doesn’t behave, we may ask you additional questions about the training of your animal.

Just as any other passenger with a disability, you are entitled to any available seat in which you are qualified to use and your animal is expected to be seated in the floor space below your seat. No animals are allowed to occupy seats that are designed for passengers.

When booking your reservation, please ensure you have seat assignments before you hang up the phone. It is our responsibility to provide seating accommodation for passengers with disabilities at the first point of contact. If directed to get seats at the gate, please ask to be transferred to the CRO Desk for further direction.

Please understand that with larger service animals or passengers with multiple service animals, we may need to re-accommodate you if the animal encroaches on other passengers or extends into aisles, which would be a violation of FAA regulations.

Acceptance Guidelines

May or may not be trained to perform observable functions. However, the animal must be trained to behave properly in public settings as service animals do. Emotional support animals travel free of charge and the animal is exempt from cabin allotment. Like service animals, emotional support animals can be transported in the cabin.

Delta requires documentation* (not more than one year old) on letterhead from either a licensed medical or mental health professional to be presented to an agent upon check in stating:

  • Title, address, license number** and jurisdiction (state/country it was issued), phone number, and signature of mental health professional.
  • The passenger has a mental health related disability recognized in the Diagnostic and Statistical Manual - 4th Edition.
  • That the passenger needs the emotional support or psychiatric service animal as an accommodation for air travel and/or for activity at the passenger's destination.
  • That the person listed in the letter is under the care of the assessing physician or mental health professional.

*Passengers may use a signed or stamped digital letter on their mobile device as long as the information can be verified (i.e. phone numbers, email addresses etc.)
**Professional's license number is recommended.

A kennel is not required for emotional support animals if they are fully trained and meet same requirements as a service animal. Passengers should ask to speak to the Complaint Resolution Office (CRO) if they encounter any issues while traveling with emotional support animals.

Other carriers:


American Airlines

Southwest Airlines



Virgin America

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