Irina Zhou’s five-year-old cat has gained about a kilogram every year for the past three years. She knows the extra weight puts her pet at risk of obesity-related diseases and could even shorten his life. “My parents just can’t bear to see the cat go hungry,” the 29-year-old Zhou said. “If the weight starts to affect his health, I might consider trying weight-loss medicines for him.” The idea of using obesity drugs for pets drew public attention after Fosun Pharma’s unit Yao Pharma signed a...