Abstract: Cage (1) for transporting pets, such as dogs or cats, on mobile vehicles of the type comprising: —at least one front wall (2), at least one back wall (3); at least two opposite side walls (4) and at least one bottom wall (5), characterized by comprising at least one passive safety system (10) comprising: —at least one inflatable element (13); —at least one capsule connected to said inflatable element (13); —said capsule containing at least one explosive substance; said capsule being configured to make the explosive substance explode such as to emit gas adapted to inflate said inflatable element; —at least one detonator configured to trigger the explosive substance contained in said explosive capsule; —at least one sensor configured to detect a deceleration of said cage and to send a signal; —at least one electronic control unit configured to receive a signal from said sensor, to process it and to send an igniting command to said detonator.