Here's a breakdown:
* Normal development: In male dogs, the testicles develop inside the abdomen and descend into the scrotum, a pouch of skin located between the hind legs, typically by the time they are 6-8 weeks old.
* Cryptorchidism: Sometimes, one or both testicles may fail to descend into the scrotum. This is called cryptorchidism.
* Visible testicles: The testicles are located within the scrotum, which is visible between the hind legs.
So, to answer your question more specifically:
* The testicles descend into the scrotum, they don't "come out" in the sense of suddenly appearing.
* If a dog has cryptorchidism, one or both testicles might remain in the abdomen, which is an abnormal condition.
Important Note: If you have concerns about your dog's testicles, it's always best to consult a veterinarian for professional advice.