a good while ago.. there is a german documentary about it. they travel to China and try to find restaurants who have dogs or people who eat dogs.. they didn't found any. every stranger told them that they don't eat dogs anymore since years. thw documentary too is really old (like 5 years ago?)..so i would say.. a really long time.
https://en.wikipedia.org/wiki/Lychee_and_Dog_Meat_Festival