Cats and dogs give birth to usually several pups in their litter can be up to 8 kids (about 2-3). It is believed that for this reason, puppies and kittens are born, strictly speaking, premature: if they had "matured" in the mother's womb, that huge belly and related difficulties would create a serious danger to her life and find food.
Eyes in kittens and puppies open at 7-14 day life. After opening the eyes of puppies and kittens in the first few days are able to distinguish only bright moving objects and gradually become fully sighted.
The relationship between maturity of the newborn and the ability to quickly transition to independent living is well seen on the example of rabbits and hares. The young rabbits are born blind, deaf and naked. Bunny in the first two weeks can only eat mother's milk. They can afford it, as the rabbits burrowing animals. But the hares are born with open eyes, good ears and covered in fluff, the benefit of zichichi hatching offspring for 2 weeks longer than rabbits. Within a few days after the birth of a rabbit, unlike Bunny, can depart from the mother and to try other food, except milk.
The rabbit is forced to become self-reliant as quickly as possible, because rabbits do not build and holes and not tied to any territory, and therefore their newborn offspring is more endangered than in rabbits.
By the way...
Although human babies eyes are open from the first day after birth, this does not mean that the newborn well see! The picture that observes the child in the first days is a whitish haze. A few days later, children begin to distinguish large objects, and they see upside down - the brain has not yet learned to make a correction taking into account the fact that on the retina the image gets inverted... read More.