THE UEINARY APPARATUS. 345 



brane, and gives rise to irritability of the bladder and 

 incontinence of urine. Fiirstenburg gives the following 

 composition as an average analysis of urinary calculi of 

 the ox : — Carbonate of lime, 84'8 ; carbonate of magnesia, 

 10*0; carbonate of iron, 0"6 ; organic matter, 1*6; water 

 and loss, 1*6 ; silicic acid, inconstant. The presence of 

 calculus in the bladder sometimes gives rise to hgematuria ; 

 generally, however, no alteration is observable in the 

 character of the urine further than a somewhat copious 

 sediment. In all cases there is a straddling movement with 

 the hind limbs and stiffness about the loins. Sometimes 

 the stone becomes fixed in the urethral passage, whereby 

 it interferes with the expulsion of the urine, and the 

 signs of retention are present and urgent. This con- 

 dition takes place in the male, and the urethra becomes 

 distended with urine to the obstructiouo It may result 

 in rupture of the urethral passage, a condition which may 

 also arise from injury (see ^Veterinarian,^ vol. xxi, p. 204). 

 Exploration per rectum is often useful in cases of cystic 

 calculus. The bladder may be found distended with urine, 

 as in spasm of its neck, but the calculus is perceptible, and 

 sometimes may be removed by pressure, whereupon a rapid 

 flow of urine results. In these cases, too, there is not gene- 

 rally complete retention, but the flow, at first free, suddenly 

 ceases, and the animal lashes its tail, grinds its teeth, moves 

 the hind feet, and makes violent expulsive efforts, which 

 only tend to fix the obstructing agent more firmly in the 

 passage. Surgical methods are resorted to for the relief 

 of this condition. Lithontriptic or " slow dissolving medi- 

 cinal agents ^' have been found wanting ; stimulants are 

 only palliative. There are three forms of operation. 



Lithecstasy — Dilatation of the Urethra — is especially 

 resorted to in the female. It consists in the frequent dis- 

 tension of a bladder introduced into the urethral passage, 

 leading to dilatation to such an extent that the stone may 

 pass. It is seldom resorted to in veterinary practice. 



Lithotrity consists in crushing the stone, whereby, being 

 reduced to the state of gravel, it can be expelled through 

 the urethra. The instruments by means of which this is 



