Many countries nowadays have been recognizing and allowing emotional support animals with legitimate esa letter for travel issued by recognized veterans and doctors to travel on airlines in recent years, in compliance with rules and regulations. Accepted service animals can also be used by those who are deaf or have impaired vision, mobility, or convulsions. This allowed owners to travel with small dogs and cats in special carriers that fit under the cabin seat. However, not all airlines have allowed this, and others have specified that pets are not allowed in the cabin. Some airlines carry animals as cargo only in ventilated and heated holds.