Delta Air Lines will begin limiting the number of emotional support animals that passengers can bring on its airliners, a shift that comes as lawmakers tighten rules governing the practice.

Starting July 10, the Atlanta-based carrier will allow only one such pet per customer and stop considering pit bulls in the category. Congress began considering legislation narrowing the definition of such animals for air-travel purposes earlier this year after a series of incidents, including one in which a dog died in an overhead bin during a United Airlines flight.