One thing you have to understand is they don't treat animals like human beings. Also they don't develop affection towards dogs as westeners do. So in their eyes, dogs, cats, pigs, cows, chicken, fish... are the same aniamls. Another reason for them to do so may be because they don't have the tools or know the methods to deliver a quick kill. They have to resort to the primitive ways, like how people were executed in ancient times.
>>I'm sure MANY former POWs would also have a word to say about the "tenderness" of their Asian captors hearts.
As for POWs, there was politics involved.
AK-47s and handguns are plentiful I would think. If not, there is always a machete or similar instrument that could be used to chop off the head.
Slicing off a dog's penis and letting him bleed to death is one of the most horrendous tales I've ever heard. From accounts of POWs, Asians did not reserve that sort of treatment just for dogs.
I'm not saying that all Asians are capable of such atrocity, but there are obviously some that do and feel no shame or remorse over it.