If a dog still gets its period after hysterectomy, it may be caused by incomplete sterilization. The sterilization operation of a female dog requires complete removal of the uterus and ovaries to achieve the purpose of sterilization. If the uterus and ovaries are not completely removed during the sterilization operation, sex hormones will still be produced in the body, causing the dog to go into heat. It is recommended that the owner take the dog to the hospital for a X-ray examination to confirm whether it is completely removed. If not, it needs to be surgically removed again.