Publisher's Synopsis
Dogs come in a wide range of shapes and sizes. It is difficult to imagine that a large Great Dane and a tiny poodle are of the same species, but they are genetically identical with the same anatomic features. All dogs have 78 chromosomes, or 39 pairs of chromosomes (humans have 23 pairs), and one member of each pair comes from each parent. The normal temperature (rectal) of an adult dog is 100-102.5 °F.Dogs have two sets of teeth. Twenty-eight deciduous teeth erupt by six to eight weeks of age, and by the time puppies are six to seven months old these deciduous teeth are all replaced by 42 adult teeth. The permanent teeth include incisors, which are used to nip and bite; canines, which tear and shred flesh; and premolars and molars, which shear and crush. In short, a dog's teeth serve as weapons and as tools for cutting or tearing food. The canines are the upper and lower fangs for which the dog family was named. As in most carnivores, the teeth are high-crowned and pointed, unlike the broad, grinding teeth of many herbivorous animals.The teething process can be difficult for puppies. Their gums hurt and become swollen, they may lose their appetites, and they may have mild intermittent diarrhea.