Vietnamese students and workers began bringing boxes full of puppies back from the former Soviet Union last year, once they heard that miniature breeds were all the rage in Hanoi.
'It's popular now because if you have a dog and can feed it, it means you're rich,' said a young female factory worker, who flew home from Moscow with six squirming puppies in a carry-on bag.
The long-haired, mostly white canines proliferating in Hanoi are popularly called 'Japanese dogs', though Japanese residents say they have never seen them before. Their owners maintain that the dogs, which resemble Pekinese, are purebreds.
Previously, only two types of dog could be seen here - stocky, mangy mongrels that were always in danger of becoming someone's dinner, and Alsatians brought back from the former East Germany to serve as guard dogs.
'Japanese dogs' are too scrawny - and too valuable - to be eaten. While some people buy them to look rich, others breed them to get rich.
A two-month-old puppy, whose parents were probably purchased for around dollars 40 ( pounds 21) each last year in Russia, can fetch more than dollars 500 in Hanoi, according to local dog breeders.
A handsome adult male is worth four times as much, since he can earn his owner dollars 45 per coupling in stud fees, said a man who used to raise Alsatians before switching to small dogs.
'It's these dogs who feed us,' said the man, who, like other Vietnamese interviewed, asked not to be named.
The scent of profit has attracted more than just animal lovers to the dog trade, in a country that remains one of Asia's poorest. Just ask David Blair, an American aid worker who was walking the family dog alongside Hanoi's Thuyen Quang lake when two men on a motorcycle roared up behind him. They cut the leash, grabbed the dog, and raced off.
Mr Blair learnt that he was by no means the first city resident to fall victim to dognappers, and that many had recovered their pets after paying a ransom.
'We put the word out on the street that we were offering a reward but without results,' he said. 'Our guess is that he was taken to China and sold there.'
Organised groups are involved in trafficking all kinds of items to and from southern China, whose ravenous markets have become increasingly accessible since the normalisation last year of Sino- Vietnamese relations.