First you have to teach your dog to howl or growl, you can do this buy making them excited and when they start barking wait until they start howling or growling but BE CAREFUL! That the growl is not aggressive it should be more like a moan. Then say a command, say it after they have howled or growled. Once you have done this say the command and keep repeating " I love you" or an easier ine may be "hello" until they start to howl or growl so its sounds like I love you or hello. Not many dog breeds can do this but some can like huskies, collies, jack russel and pugs.
HOPE THIS HELPS XX
HOPE THIS HELPS XX