Which of the following is not a sign of heat in animals?

Mucous discharge from the rectum is not a sign of heat in animals. Heat, also known as estrus, refers to the period in the reproductive cycle of female animals when they are fertile and can mate with males to produce offspring. During heat, females exhibit various physical and behavioral changes to signal their readiness to mate. These changes include swelling of the vulva, increased vaginal discharge, mounting behavior, and restlessness. Mucous discharge from the rectum is not a typical sign of heat in animals. It can indicate a digestive issue or infection, and it is not related to reproductive readiness. Therefore, if you observe mucous discharge from the rectum in your animal, it is important to seek veterinary attention to identify the cause of this symptom.