The puppy comes into the world blind, and lie remains that way for nine days. This is nature's method of ensuring that he will not wander away from his mother and come to his death from cold or hunger. His blindness also protects his eyes while he is very young and has not yet acquired the ability to protect them himself by keeping out of the way of the sharp little claws of his brothers and sisters. At this time a puppy's nose is his only guide. The first sense to be developed in the puppy is the instinct to nurse, and the next is his sense of smell. This commences to develop immediately after birth, and eventually becomes even more important to the grown dog than eyes or ears.
Like a baby, the puppy lives his life according to schedule, though in his case nature and not the mother imposes the routine. Between four and six weeks he must stop nursing and learn to eat solid food. The baby teeth erupt four or five weeks after birth, and stay with him until he is five or six months old. The first teeth to appear are the incisors. These show through the gums at around four weeks. The canines are next, and then the molars.
A dog has forty-two teeth when his dentition is complete, twenty in the upper jaw and twenty-two in the lower. These consist of six incisors in each jaw, two canines in each, twelve molars in the upper jaw and fourteen in the lower. Should the puppy experience any difficulty in getting rid of his first or "milk" teeth, it is well to remove them, for their looseness will cause pain.
At twelve months the puppy becomes an adult in an official sense. Between the ages of six and twelve months he may be entered as a puppy in the various shows, but after twelve months he must take his chance with the grown dogs though he will not yet have attained his full growth. The time when full height and weight are reached varies with the breed. The larger the dog, the longer time he will take. He will reach his matured height first, possibly as early as nine months, but he is still a gangling youngster that will not come to the top of his form until he is around two years of age. Small breeds may do so at fifteen months. Once the full height has been reached, there will be no more development in this direction. The weight will change, but once the skeleton is completely formed, there will be no variation in the height of any dog.
Young puppies, and grown dogs for that matter, derive great enjoyment from chewing anything they can get hold of. This should be kept in mind, and wood, metal, broken glass, or anything which is likely to splinter must be kept from them. A very small particle of some sharp material may puncture the intestine and cause death from either peritonitis or internal hemorrhage. Even rubber balls should not be given as toys if they are painted, and they must always be too large for the puppy to swallow. Do not give him a ball which he can chew into pieces.