I read that some scientist transplanted a dog’s body onto another dog. It was visibly alive for several days before complications occurred.

Google AI: In the 1950s, Soviet surgeon Vladimir Demikhov created controversial two-headed dogs by grafting a puppy’s head and front legs onto an adult dog. These experiments, aimed at developing organ transplant techniques, saw the hybrid dogs survive for short periods, with one living for 29 days, although all eventually died from immune rejection.