The red piece of flesh coming out of the dog's urethral opening is the dog's genitals. This only happens to male dogs. There is no need to worry. It is not a disease. It will only come out when the dog is in heat. Male dogs will also have secretions when they are in estrus, so they need to pay attention to hygiene, avoid urinary tract infections, and bathe the dog regularly. If you don’t want the dog to be in estrus, you can take the dog for neutering surgery to prevent the male dog from coming into contact with the female dog in estrus. Lost.