Bull dogs are one of the breeds that are not usually accepted for transport.
The sex of the dog would not likely have made a difference.
The short facial snout when pressed up against the side of a solid wall shipping container
reduces the animals ability to breath correctly.
Sadly this dog more in likely suffocated if not in a wire mesh shipping container.
Other factor - the flight crew did not monitor the cargo hold for the proper atmosphere/pressurization
or the dog was placed in a non pressurized hold.