Daft Dog
It seems to have been because of the type of dog which is one of the world's more daft and sensitive breeds:
“Cathay requires all passengers to have the correct health certificates and travel permits for pets,” the paper reported. “However, the airline does not allow a number of breeds of dog to fly either in the cabin or cargo hold, including Cavalier King Charles spaniels – which is believed to be the breed of the Rogen’s dog.”