61 



(d) a large saccular reservoir in the center of the kidney into which all 

 iiriuiferous tubes pour their secretions and from which the urine is 

 carried away through a tube (j, (ureter), which passes out of the notch at 

 the inner border of the kidney and which opens by a valve-closed orifice 

 into the roof of the bladder just in front of its neck. The bladder is a 

 dilatable reservoir for the retention of the urine until the discomfort of 

 its presence causes its voluntary discharge. It is kept closed by cir- 

 cular muscular fibers surrounding its neck or orifice, and is emptied by 

 looped muscular fibers extending in all directions forward from the 

 neck around the blind anterior end of the sac. From the bladder the 

 urine escapes through a dilatable tube (urethra) which extends from- 

 the neck of the bladder backward on the floor of the pelvis, and in the 

 male through the penis to its free end, where it opens through a pink 

 conical papilla. In the mare the urethra is not more than an inch in 

 length, and is surrounded by the circular muscular fibers closing the 

 neck of the bladder. Its opening may be found directly in the median 

 line of the floor of the vnlva, about 4| inches from its external opening. 



General sijmptoms. — These apply especially to acute inflammations 

 and the irritation caused by stone. The animal moves stiffly on the 

 hind limbs, straddles, and makes frequent attempts to pass urine, which 

 may be in excess, deficient in amount, liable to sudden arrest in spite 

 of the straining, passed in driblets, or entirely suppressed. Again, it 

 may be mo(lifie<l in density or constituents. Difficulty in making a 

 sharp turn, or in lying down and rising with or without groaning, drop- 

 ping the back when mounted or when pinched on the loins is sugpest- 

 ive of kidney disease, and so to a less extent are swelled legs, dropsy, 

 and diseases of the skin and nervous system. The oiled hand intro- 

 duced through the rectum may feel the bladder beneath and detect any 

 over-distension, swelling, tenderness, or stone. In ponies the kidneys 

 even may be reached. 



Examination of the urine. — In some cases the changes in the urine 

 are the sole sign of disease. In health the horse's urine is of a deep 

 amber color and has a strong odor. On a feed of grain and hay it may 

 show a uniform transparency, while on a green ration there is an 

 abundant white deposit of carbonate of lime. Of its morbid changes 

 the following are to be looked for: (1) Color: White from deposited 

 salts of lime ', brown or red from blood clots or coloring matter ; yoUow 

 or orange from bile or blood-pigment 5 pule from excess of water, or 

 variou sly colored from vegetable ingredients (santonin makes it i"ed, 

 rhubarb or senna, brown; tar or carbolic acid, green). (2) Density: 

 The horse's urine may be 1.030 to 1.050, but it may greatly exceed this 

 in diabetes and may sink to 1.007 in diuresis. (3) Chemical re-action^ 

 as ascertained by blue litmus or red test papers. The horse on vege- 

 table diet has alkaline urine turning red test papers blue, while in the 

 sucking-colt and the horse fed on flesh or on his own tissues (in star- 

 vation or abstinence during disease) it is acid, tui-ning blue litmus red. 



