The more babies a woman is carrying, the more likely it is that her uterus will swell, triggering contractions, says Brian Brost, M.D., associate professor of maternal/fetal medicine at the Mayo Clinic, in Rochester, Minnesota. An early due date isn't the only challenge to having multiples.
Dogs do not menstruate like humans do. Instead, they come into estrus (come into heat/season) about twice a year, once they have reached sexual maturity. This can sometimes be associated with a small amount of blood from the vulva, but it is not truly a period. Female puppies can reach sexual maturity potentially as early as six months old, although the first season (which is the closest equivalent to getting their period) is often at about nine months old.
Dog Puberty. Puberty In a male dog, puberty appears around 8 or 12 months of age. Upon reaching purity, the dog will start to mark his territory (outside the house, that is) with urine, stopping at every tree and a corner to do so.n the female dog, the first estrus cycle appears around 7 or 8 months of age, and is characterized by a vaginal blood flow which can last for about 10 to 12 days and is followed by ovulation (fertile period).