DISEASE8 OF THE URINARY ORGANS. 139 



thrown down as insoluble silica when a stronger acid displaces it by 

 combining with the potash to its exclusion. In cases of siliceous 

 calculi, accordingly, the appropriate chemical prevention is caustic 

 potash, which being present in the free state would attract to itself 

 any free acid and leave the silica in its soluble condition as silicate of 

 potash. 



STONE IN THE BLADDER (VESICAL CALCULUS, OR URETHRAL CALCULUS). 



Stone in the bladder may be of any size, but in the ox does not 

 usually exceed half an inch in diameter. There may, however, be a 

 number of small calculi; indeed, they are sometimes so small and 

 numerous as to form a small pulpy magma by which the bladder is 

 considerably distended. 



Symptoms. — The symptoms of stone in the bladder may be absent 

 until one of the masses escapes into the urethra, but when this occurs 

 the escape of urine is prevented, or it is allowed to pass in drops or 

 driblets only, and the effect of such obstruction becomes manifest. 

 The point of obstruction is not always the same, but it is most fre- 

 quently at the S-shaped curve of the penis, just above the testicles or 

 scrotum. In cows and heifers the urethra is so short and becomes so 

 widely dilated during the urination that the calculi easily escape in 

 the flow of liquid and dangerous symptoms practically never appear. 



Even in the male the signs of illness are at first very slight. A 

 close observer may notice the cylinders of hard, earthy materials 

 encircling the tufts of hair at the opening of the prepuce. It may 

 further be observed that the stall remains dry and that the animal has 

 not been seen to pass water when out of doors. The tail may at times 

 be gently raised and contractions of the muscle (accelerator urince,) 

 beneath the anus (PI. IX, fig. 2) may take place in a rhythmical or 

 pulsating manner. But as a rule no symptom is noticed for a couple 

 of days, only the animal is lacking in his usual spirits. By this time 

 the constantly accumulating urine has distended the bladder beyond 

 its power of resistance and a rupture occurs, allowing the urine to 

 escape into the cavity of the abdomen. Then dullness increases; the 

 animal lies down most of his time; he becomes stupid and sometimes 

 drowsy, with reddish brown congestion of the lining membrane of the 

 eyelids; pressure on the abdomen causes pain, flinching, and perhaps 

 groaning, and the lowest part of the belly fluctuates more and more as 

 the escaping urine accumulates in greater and greater amount. If at 

 this stage the oiled hand is introduced into the rectum (last gut), the 

 animal flinches when pressure is made downward on the floor of the 

 pelvis, and no round, distended bladder is felt. If the same examina- 

 tion is made prior to the rupture the rounded, tense, elastic bladder 

 is felt extending forward into the abdomen, containing one or two 

 gallons of liquid. There may be uneasy shifting of the hind limbs 



