DISEASES OF THE HORSE. 77 



tubes leading from the sacs inward toward the second, or medullary, 

 part of the organ; (J) the internal (medullary) part, made up in the 

 main of blood vessels, Ij-mphatics, and nerves extending between the 

 notch on the inner border of the kidney to and from the outer Avascular 

 portion, in which the secretion of urine is almost exclusively carried 

 on; and (d) a large saccular reservoir in the center of the kiduej", into 

 which all uriniferous tubes pour their secretions and from which the 

 urine is carried away through a tube g (ureter), which passes out of 

 the notch at- the inner border of the kidney and which opens by a valve- 

 closed oritice 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 circular muscular fibers surrounding its neck or orifice, and 

 is emptied by looped muscular fibers extending in all directions for- 

 ward 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 ma}^ be found 

 directly in the median line of the floor of the vulva, about 4^ inches 

 from its external opening. 



GENERAL SYMPTOMS OF DISEASE. 



These apply especially to acute inflammations and the irritation 

 caused by stone. The animal moves stifil}^ on the hind limbs, strad- 

 dles, 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 modified 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 sugges- 

 tive of kidne}^ disease, and so to a less extent are swelled legs, dropsy, 

 and diseases of the skin and nervous sj^stem. The oiled hand intro- 

 duced through the rectum may feel the bladder beneath and detect 

 any overdistention, 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 transpar- 

 ency, while on a green ration there is an abundant white deposit of 

 carbonate of lime. Of its morbid changes the following are to be 



