THE URINARY APPARATUS. 347 



Calculus op the Urethra is not uncommon in the ox, 

 but is generally a small vesical stone on its way to the 

 exterior. It has been stopped either by spasm of the 

 urethra or by the curvatures of the passage through the 

 penis, and gives rise to retention of urine of an obsti- 

 nate character. The symptoms are urgent, and must be 

 relieved by incision either longitudinally or obliquely 

 across the direction of the passage. The patient must not 

 be cast for the operation. There will be little difficulty in 

 determining the seat of obstruction, for the urethral 

 canal is distended to the same point. 



Stricture op the Urethra may be organic or functional. 

 In the former case there is thickening of the lining mem- 

 brane of the canal, in the latter spasm of the accele- 

 rator urinae muscle. These give rise to more or less 

 complete impediment to the passage of urine. They are 

 seldom seen in cattle. 



Preputial Calculus generally assumes the form of 

 calcareous deposit around the hairs hanging in a tuft 

 from the prepuce. These deposits are mainly phosphatic, 

 and depend upon excess of salts in the food. The slow 

 and unenergetic expulsion of urine predisposes to their 

 formation. They must be removed by excision of the 

 hairs, around which they sometimes accumulate to such 

 a degree as to cause obstruction to the flow of urine. 

 Modification of diet so as to avoid excess of salines, also 

 free supply of water and other solvents, must be looked 

 upon as prophylactics against calculous diseases. 



