RETENTION OF URINE 351 



the urethral canal. It sometimes occurs as a result of paralysis following 

 on abnormal conditions of the brain and spinal cord. Among the 

 mechanical obstructions may be mentioned enlargement of the prostate 

 gland, the descent of calculi from the bladder into the urethral canal, 

 stricture, morbid growths, swelling of the sheath, &c. Want of opportunity 

 to stale is another frequent cause, as when thoughtless persons drive long 

 distances and neglect to take the animal out of harness. It may be men- 



Fig. 145. Retention of Urine in the Mare passing the Catheter 

 A, Bladder, B, Catheter, c, Valve overlapping entrance to bladder. D, Vagina. E, Uterus. F, Rectum. 



tioned, inter alia, that while some horses will almost insist upon pulling up 

 for the purpose of passing urine, others require perfect quietude, and can 

 only be induced to stale by taking them on to a straw bed. It is occasion- 

 ally found that a horse will not relieve himself while on a journey, although 

 taken out of a carriage, unless the bridle is removed or the breeching. 

 The inability to pass water after compulsory retention arises out of a 

 temporary paralysis of the muscular coat of the bladder, the result of 

 undue stretching. 



Symptoms. Repeated but unsuccessful attempts to urinate, standing 

 with the front and hind legs far apart, straining, grunting or groaning, 

 and possibly the passing of a few drops of urine, which seem rather 



