The male dog is one and a half years old. He was sterilized last night and the wound opened. The doctor said that there is no need to sew again, and it will heal naturally. Invisible testicles seem to be still there. Was the sterilization successful? According to the information you provided, your male dog, one and a half years old, was sterilized last night, but the wound opened. The doctor told you to stop sewing and let the wound heal naturally. You also mentioned that invisible testicles still seem to exist despite sterilization.

First of all, cryptorchidism means that the testis is hidden in the abdominal cavity or inguinal canal, not in the scrotum. In sterilization, doctors usually remove hidden testicles to ensure that the testicles are completely removed.

If your dog's wound is split, you need to follow the doctor's advice and let the wound heal naturally. In the meantime, you need to keep the wound clean and dry, and use drugs or disinfectants according to the doctor's instructions.

As for the success of sterilization, more information is needed to determine. If the doctor has removed the testicles, sterilization should be successful. However, if you still see the existence of invisible testicles, then the operation may not be completely successful. In this case, you should further communicate with the doctor and consider having another operation.

In short, if your dog's wound is cracked, it needs to be treated according to the doctor's advice. More information is needed to determine whether sterilization is successful. I suggest you communicate with the doctor further.