In medicine, etiology refers to the many factors coming together to cause an illness. It is normally the focus of epidemiological studies. The etiology of scurvy is a good example. With scurvy, sailors going to sea often lacked fresh vegetables.
So, how long are dogs pregnant? The answer varies depending on several factors, but the average length of gestation, aka pregnancy, lasts between 58 to 67 days, with 63 days being the average delivery date.
To prevent (or encourage) pregnancy, its important to know when your dog can become pregnant. Your dog can get pregnant during her heat cycle (or estrus). Dogs DO NOT go through menopause the way humans do. As they grow older they are less fertile, but it is possible for your older dog to become pregnant. Dogs typically have two heats per year.