751 



Combined Paralysis of the Tail and of the Sphincter. 



tail. At the trot this hangs lifeless between the buttocks 

 and swings from side to side. At rest it is quite motionless or, 

 if the paralysis remains nnilateral for a time it may be moved 

 to one side only. During defecation and urination it is not 

 lifted. As a result of atrophy of the muscles, the tail appears 

 thinner than normal and in the later stages there is a depression 

 between the posterior and upper gluteal regions. As a rule the 

 atrophy is not symmetrical on both sides of the body. The tail 

 offers little or no resistance to passive movements to one or both 

 sides. The paralyzed muscles show electrical degeneration re- 

 action or the absence of electrical or mechanical irritability 

 (Dexler). 



There is usually loss of sensation of the skin, the joints 

 and muscle of the tail, the perineum, root of the tail, posterior 

 gluteal region, mucous membranes of the rectum and vagina 

 on both sides, though perhaps not to the same extent. One side 



alone may remain insensitive 

 for a time (figs. 112-133). 

 Pricking the muscles or 

 twisting the tail causes no 

 reaction. Similarly, heat, 

 cold and electrical stimula- 

 tion are without effect. In 

 the later stages there is 

 usually a narrow hyperes- 

 thetic zone bounding ante- 

 riorly the anesthetic area 

 (Hutyra and Marek), or 

 there may be circumscribed 

 hyperesthetic areas. This 

 hyperesthetic zone gradual- 

 ly advances with the exten- 

 sion of the area of anes- 

 thesia in the forward direction. The anesthetic area merges 

 into the area that is hyperesthetic or of normal sensibility in 

 many cases through a very narrow zone that is hypoesthetic. 



There is marked retention of the feces and defecation may 

 be impossible. As a rule balls of feces are passed only during 

 exercise. The anal region is soiled with feces and in the case 

 of mares with urine, the sphincter is relaxed, the posterior 

 portion of the rectum is widely dilated and packed with feces. 

 Masses of feces project from the anus and after these are re- 

 moved fresh masses are pushed on from the anterior portion 

 of the rectum and again fill up the dilated portion (figs. 112 

 and 113). 



For a time micturition is quite normal, but in the later 

 stages there are abnormalities in the manner in which the urine 

 is passed. Both during rest and movement it may be passed 

 in small jets without effort or it may be passed continuously in 



Fig. 111. Combined paralysis of the tail 

 and sphincters. Cross section through the 

 Cauda equina shown in fig. 110 after fixa- 

 tion in Miiller's solution. Tlie dark areas 

 mark the position of the nerve fibers which 

 are surrounded by a large amount of con- 

 nective tissue. 



