174 THE EXTERIOR OF THE HORSE. 



One of the most frequent diseases of this region is pruritus, occasioned by 

 the uncleanliness of the skin of the stump, sometimes by the presence of intes- 

 tinal worms (oxyures), or the itch, which is manifested by depilations, excoria- 

 tions, and eschars, more or less extensive. These aflections always begin by a 

 peculiar straightening of the hairs, which should attract the attention of the 

 purchaser ; otherwise they are not serious. 



The crupper quite frequently causes wounds when it is not Avell fitted or 

 padded, especially in animals low in front, in which the saddle and harness have 

 a tendency to slip towards the withers. These lesions are also observed on horses 

 of a good conformation which are harnessed without the breeching, and which are 

 required to descend steep hills. However caused, these wounds sometimes make 

 it impossible for the animal to endure the crupper. We have seen them so deep 

 that they could take the place of nicking. Generally it is sufficient to increase the 

 thickness of the crupper or to discontinue the use of this part of the harness, to 

 enable the sores to heal at once. 



We shall further on speak of cicatrices, longitudinal or transverse, traces of 

 docking or nicking ; of fistulte which require a long time to heal, and which com- 

 plicate these operations ; finally, of melanotic tumors, sometimes ulcerated, which 

 cause a black, fetid, and unclean discharge. 



B.— The Anus. 



Situation ; Limits ; Anatomical Base. — The anus is the 

 posterior orifice of the digestive tube. Situated uuderneath the tail 

 and above the perineum, it has for its base the most posterior muscular 

 fibres of the rectum, surrounded by a strong sphincter, related on the 

 sides to two retractor muscles (ischio-anal). Its skin is fine, pliable, 

 oily, devoid of hairs, and black even in white horses ; we can some- 

 times find, however, as in the vicinity of other natural openings, pinkish 

 surfaces deprived of pigment, called leprous spots. Internally it is 

 covered by the rectal mucous membrane. 



In vigorous and healthy horses the anus forms a rounded projection, 

 firm, depressed, and folded at its centre like the mouth of a purse ; it 

 is described SiS prominent. In animals weakened by age, work, and 

 sickness, it appears sunken, soft, and sometimes gaping. It shows, in 

 this case, its mucous interior, and becomes powerless to retain the faecal 

 matters, which — poorly moulded, on account of the general atony of the 

 digestive tube — are expelled with much gas during locomotion or while 

 the animal is taking a deep inspiration. This state is characterized by 

 giving the animal the epithet evacuator. 



Diseases and Blemishes. — The anus is especially to be exam- 

 ined in regard to its alterations. 



Let us speak first of the melanotic himors in certain white or gray horses, 

 the volume of which is an obstacle to the expulsion of the excrements. These 



