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.
Answer Wiki. Female dogs are usually pregnant for 9 weeks, varying from 60-67 days. It is sometimes difficult to determine exactly when a bitch is due to whelp because matings may occur over many days during the estrus cycle. This affects when puppies are born rather than the breed, as there are few differences in gestation length regardless of breed.