Dogs are found everywhere in the world, in first world countries they are treated by their owners in a loving home but in countries such as third world countries they roam around filthy streets without owners and breed wildly and often die of diseases.
Female dogs do not go through menopause, although their cycles will become irregular and fertility becomes unpredictable as they become older. Dogs over around 7 or 8 years are not usually considered right for breeding, but can still be fertile. Canine sperm can be in the Fallopian tubes for 10 to 11 days so if a female dog is bred 10 days before the eggs can be fertilized, she will appear to have a gestation length of 70 days. If she is bred on the day the eggs can be fertilized, her gestation length will appear to be 60 days long. The species reproduce by Cross Fertilization and fertilization is internal as the sperm swims to fertilize the egg. A female dogs uterus is the shape of a pear unlike a human's female uterus. The reason internal fertilization is an advantage because they can keep their fetus safe in the stomach, and they dont have to waste as much energy producing eggs and sperm.
Female dogs often have a hymen, which is where the vagina and 'vestibule' work together together during embryonic development. The female’s gestation period is nine weeks. Dogs are viviparious so meaning they give borth to live babies. In the dog, 'N=39'. The dog's diploid number is 78, so each sperm and dogs ovum contain 39 dna cells.
Pups and their mother have a strong bond in the early weeks of their growth. The mother looks after her litter, keeps them out of trouble, licks them clean and feeds them with her milk. Nowadays a lot of dogs are bred by human which means the mother may not be fully taking care of her pups on her own as humans do help out. As dogs get older around the age of 6 weeks they begin to gain independence and social skills with other dogs and the mother is not as involved in their life as before. Humans having a direct involvement in a dogs life from an early stage is a good thing because it helps the pup familiarize its self with humans and that is useful as most dogs are pets nowadays.With breeders and organizations like that a dogs development is carefully planned out and monitored throughout their life so they don't get a chance to go through that process without any humans involved which from natures perspective may not be a good thing.