Air Canada has issued a clarification on their definition of emotional support (ESA) and psychiatric service animals. This is the first airline to address this classification of animal. Here is their policy:

Dogs as emotional support or psychiatric service animals
If you wish to travel with a dog* as an emotional support or psychiatric service animal, you will need to ensure that your animal is harnessed. More than 48 hours prior to departure, you must also provide supporting documentation in the form of an original letter on the letterhead of a licensed mental health professional (e.g. a psychologist, psychiatrist or licensed clinical social worker), dated within one year of your departure date.

The letter must confirm that:

• • You have a mental or emotional disability recognized by the DSM-IV (Diagnostic and Statistical Manual of Mental Disorders)
  • You need your dog for emotional or psychiatric support during travel and/or at destination
  • The person who prepared the document is a licensed mental health professional

You are currently under the care of the licensed mental health professional who prepared the document

The letter must also provide information on the mental health professional?s license (i.e. type of licence, date issued, and issuing authority).
*NOTE: Air Canada does not accept animals other than dogs as emotional support or psychiatric service animals. ESAs are accepted only on flights to or from the United States or?flights with an Air-Canada operated flight through a US-based airline.

More information on Air Canada pet policies.