ANATOMY OF THE DOG— 10 



Digestive System 



Caecurn 

 (Appendix) 



Svnall Intestine 



Do§ World/ 



taken into the mouth becomes a part of the 

 living tissues of the body. This process is 

 known as digestion ; and the transfer of the 

 digested food into energy and tissue is known 

 as assimilation. 



The route of the digestive system is the ali- 

 mentary tract ; it may be said to extend from 

 opening to opening, from the mouth to the 

 anus or the rectum. 



It is divided into — 1. mouth, 2. esophagus, 

 3. stomach, 4. small intestine, 5. large intes- 

 tine. Along with these we must consider the 

 digestive glands, the liver, spleen and 

 pancreas. 



Saw-Toothed Lower Lip 



The start of the journey is at the opening 

 gate, the mouth, which cuts, grinds and breaks 

 up the food for digestion. In the dog the 

 lips being thin and mobile, do not play an 

 important part in the seizing of food as is 

 true with herbivorous animals such as the 

 horse and cow. 



It is interesting to note that the upper lip 

 has a central groove while the edges of the 

 flaccid lower lip are highly dented or saw- 

 toothed in outline. 



Dogs "Throw" a Drink 



Water is taken into the mouth by lapping, 

 a throwing-back of the tip of the tongue 

 toward the roof of the mouth. 



Gulping Not a Vice 



The dog chews very little at all except when 

 crushing bones and eating hard food such as 

 dry biscuit. Gulping is the customary, natural 

 act of the dog. 



As saliva is not a particularly important 

 juice in the digestion of the food in a dog, as 

 it is in the human, it is not necessary that 

 the dog chew food thoroly. The shape of the 

 teeth indicates that their function is to tear 

 rather than to grind. 



The muscles of the teeth and jaws are 

 strong because the dog does with his jaws 

 most of the things we do with our hands. 



The salivary glands secrete and pour 

 saliva into the mouth for the purpose of soft- 

 ening the food. These glands are named 

 parotid, submaxillary, sublingual, and orbital. 

 A Superstition about Dogs 



The tongue is thin, long and mobile. The 

 size and shape vary with the breed. The 

 upper surface is marked by a central groove 

 and is coated thickly with short, thin hair or 

 papillae, of rough touch to the human skin. 

 The under surface has a cord composed of 

 muscular tissue. It was presumed in old 

 times and by some today that to remove the 

 "worms" or cord from the tongue cured many 

 ills, including running fits. 



Easy to Breathe and Vomit 



The soft palate, which hangs from the roof 

 of the mouth between the back of the mouth 

 and the pharynx, is short in the dog ; hence 

 the dog can breathe easily thru the mouth 

 and can vomit easily. 



Teeth a "System" of Own 



The teeth can be considered under the sepa- 

 rate heading dentition, but as they are ^ a 

 practical part of the digestive system, we dis- 

 cuss them here. See illustration on page 16. 



The teeth are the hardest organs of the 

 body, deeply imbedded in the jaw bones. 



The first or milk or baby teeth, begin to 

 erupt as early as three weeks. All milk teeth 

 are completely broken out of the gums by the 

 age of five weeks. 



The change to permanent teeth begins at 

 four months and is ended at seven. The 

 molars are permanent teeth which begin at 

 four months and end at seven months for 

 their final appearance. 



The dog, whatever the breed or size, with 

 few exceptions, has 42 permanent teeth, 22 in 

 the lower jaw and 20 in the upper. 



Teeth are named according to the size, shape 

 or purpose — twelve incisor or cutting teeth, 

 four canine teeth (or fangs, two in each jaw, 

 one on each corner and the upper ones fitting 

 outside the lower ones — and strangely there 

 are always the six incisor teeth between the 

 two canine teeth), eighteen pre-molars, and 

 eight molars or grinders. 



The varying sizes and shapes of the dog's 

 teeth contrast with the greater uniformity of 

 the human teeth. 



In composition, the tooth has three different 

 structures — ^the enamel, the thin external 

 white part, covering the crown only; the ivory 

 or denture under the enamel ; and the cen- 

 ter, containing the nerve and small blood 



Pharynx is "Storm Vestibule" 



The pharynx is a vestibule or cavity behind 

 the mouth and at top of the neck. It is at- 

 tached to the base of the cranium above while 

 below is the larynx. It serves as passageway 

 both for air and food. Bones can easily be- 

 come lodged here. 



The Esophagus has "Waves" 



The esophagus or gullet is on the outside of 

 the neck, that is, above the trachea, or wind- 

 pipe ; when we rub the front of the neck, we 

 contact the gullet. About midway, it turns 

 behind the windpipe. 



It passes along the neck thru the chest 

 (above the heart) ,^ thru the diaphragm and 

 then quickly enters the stomach. 



