The U.S. Customs office is in the process of responding to The Dodo's inquiry regarding canine leather seizures; this post will be updated to include its response.
Though it may not be humane, it is not illegal in China to kill dogs for their skin, PETA says.
At the same time, it's important not to vilify an entire country, wrote Wayne Hsiung, a founder of animal welfare organization Direct Action Everywhere. "There are countless Chinese who have cried just as many tears," he said, "and felt just as much anger, over the murder of dogs and other animals. There are Chinese people risking their lives to help animals in need."
Here's Phoenix - fair warning, the video contains extremely graphic footage: