MOUNTED INSTRUCTION 29 



be at hand, and the head immersed frequently with the machine 

 running". 



Washing: The j^ractice of washing horses, although not injurious 

 in warm weather, should be discouraged. It is a lazy man's way of 

 grooming and while it removes dirt and sweat, the benefit derived 

 from the action of the brush on the skin and coat is lost. Cleaning 

 legs by washing should not be permitted as scratches and grease heel 

 wdll result. Whenever a horse is washed he should be treated as 

 described above for cooling out horses. 



AGE OF HORSES AS INDICATED BY TEETH 



The horse is provided with two sets of teeth, temporary and perma- 

 nent. The temporary, or milk teeth, are those of the first growth or 

 dentition. The permanent differs in appearance from the temporary 

 one by being larger, longer, darker or more yellowish in color, and 

 by having a well-marked groove down the anterior or front face of the 

 crowm. It does not have the constricted neck which is characteristic 

 of the milk tooth. 



The three principal tooth substances are called dentine, enamel, and 

 cement. The dentine composes the main body of the tooth. It is 

 protected by a covering of enamel, which is very white in color and 

 is the hardest of all animal substances. The cement is a yellowish 

 colored bony material found in the center of the tooth. The grinding 

 surface of tooth is called the table, and there is an unfolding of the 

 enamel on the table of the teeth, which forms in the incisors a cavity, 

 the bottom of wdiich is filled with cement to a depth wdiich varies in 

 different animals. The imfilled portion of this cavity forms what is 

 called the cup. The cups are deeper in the upper incisors than they 

 are in the lower ones. They soon become stained by food juices so 

 that they appear very black in color. Ordinarily after a lower incisor 

 has been in wear for three years its table surface has been worn down 

 to the cement filling and the blackened cup cavity has disappeared. 

 It is often difficult for the inexperienced observer to determine when 

 the cup has actually disappeared. He expects to see the table surface 

 perfectly level and of uniform color, whereas the enamel being so 

 much harder than either the dentine or the cement, stands in relief on 

 the table surface, and envelops a very shallow and sometimes slightly 

 stained depression (of cement) for several years after the black cup 

 cavity is considered to have disappeared. In the center of the tooth, 

 and extending almost its entire length, is the pulp cavity channel, 

 wdiich in life is filled with a fleshy tissue or pulp through the medium 

 of wdiich the tooth derives its nourishment. As the tooth is worn off 

 with age the outer extremity of the sensitive pulp, which would 

 otherwise became exposed, is changed into a yellowish colored ivory- 

 like substance that completely fills and closes the cavity. Hence, when 

 the tooth has worn down to the pulp cavity, the latter appears on the 

 table surface (just in front of the remains of the cup) as a yellowish 

 colored mark called the dental star. This usually makes its appearance 



