Dogs

Pregnancy:
The dog's gestation period  is approximately sixty-three days. From about the fifth week swelling of the abdomen becomes more noticeable.  However if only one or two pups are being carried, or the bitch is plump anyway, this sign of pregnancy may not be quite as obvious. The mammary glands enlarge and the teats become larger and pinker from about the thirty-fifth day of pregnancy. A watery secretion can be drawn from the teats three or four days before the pups are born.

When it is time to give birth, the bitch's temperature drops by a couple of degrees and she becomes restless, may stop eating, pants fitfully, and prepares her bed. This is known as pre-labor and usually lasts about twelve hours, but can be much shorter or continue for a day or two, sometimes with intervals of normal behavior. True labor begins when you see the first strain by the bitch or the appearance of a  green discharge. The maximum time that it should take to deliver each pup, counting from the first sign of straining, is two hours. The total time for whelping an average litter of four to eight pups is up to six hours.