604 



DISEASES OF SWINE 



Cause. — The active cause of cystic kidney is some obstruction 

 to the flow of urine. The block may be on one side or on both. 

 The kidney continues to secrete urine, and the fluid, if unable to 

 pass down as it should to the bladder, will dam back into the kid- 

 ney, dilate the urinary passages, and destroy the normal tissues of 



Fig. 87. — Congenita] cysts of the kidney: a, Renal artery; h, renal vein;' 

 c, ureter; d, pelvis of the kidney; e, cysts filled with clear fluid (McFar- 

 land). 



the kidney. The organ then becomes simply a dilated sac contain- 

 ing the dammed-back urine. 



Careful investigations in hogs have proved that the most 

 frequent cause of the condition is the fact that the ureters or tubes 

 leading from the kidney to the bladder are placed very low down 

 at their point of entrance into the bladder. As a result, when the 



