Beijing prosecutors are investigating the death of a Tibetan mastiff that died while undergoing a 'facelift' to 'make it look better'. Last week, the dog’s owner, surnamed Yu, said he was suing the veterinarian he claimed was in charge of the operation for 880,000 yuan (HK$1 million) - the same price he paid when he bought the dog in March. Yu said he brought the two-year-old dog to Yongchangjihe Animal Hospital for a facelift in November to make the dog more attractive to breeders. "If my dog looked better, female dog owners would have paid a higher price when they wanted to mate their dog with mine," Yu explained to the Global Times . The 1,400 yuan surgery which required cutting part of the dog’s forehead, was supposed to “straighten the flabby skin on the dog’s forehead”. According to a court press release, the dog suffered cardiac arrest during the anaesthetic process and died. Animal rights groups and activists condemned the incident and said it was unethical to make animals undergo plastic surgery. The vet, surnamed Li, declined to comment. The Global Times said he was not the vet who performed the surgery. Mastiff breeding has become a lucrative business in China as they are increasingly seen as luxury pets amongst China’s rich. Dog "farmers" buy the pups at low-prices and sell them to breeders when they are old enough to mate. The dogs, originally raised as guard dogs by Tibetan herders to protect sheep, are known to fetch prices between a few thousand yuan for a pup, to tens of millions for the high quality breeds.