CYSTIC CALCULI. 625 



question. It may, however, be taken for granted that the cause 

 lies in the quality of the food. Very probably the sheep, from 

 which the specimens were obtained, had been fed on turnips 

 and cake, both articles of food being rich in the constituents of 

 the ammonio-magnesia phosphate. 



In the horse, as well as in the domestic animals, the carbonate 

 of lime is a constant component part of the urine ; and when, 

 from some cause, it is in excess, it becomes deposited within 

 the bladder, either as a sediment or calculus. It is not, however, 

 necessary that it be present in excess ; for it is found that horses 

 which, from the nature of their work, are compelled to retain 

 their urine for many hours at a time, are most subject to 

 calculous deposits. For this reason, hunters are more commonly 

 affected than other horses. 



In the mare, cystic calculi form around nuclei, such as pieces 

 of straw, stones, or even iron. I have a specimen in my 

 possession removed from a mare, in which the calcareous matter 

 is laminated around a piece of iron. It can readily be understood 

 that any foreign body accidentally or maliciously introduced 

 into the bladder will cause a precipitation of the urine salts. 



Causes. — In addition to those enumerated, the causes of 

 urinary deposits are to be looked for in the nature of the 

 animal's food and water. Some clovers, for example, cause 

 the formation of large quantities of urine salts (often seen on 

 the floor of the stables in the form of a reddish-yellow sand) ; 

 and should any irritation of the bladder be induced, an in- 

 creased secretion of mucus will be the consequence, and a 

 nucleus is thus formed, around which the salts may be de- 

 posited. 



SpnjJtoms in the Horse. — Some stiffness in the hind limbs ; 

 repeated motions of the tail; a frequent desire to urinate, 

 exhibited by the animal stretching himself out, drawing his 

 penis, but with little or no result. At other times the excretion 

 of the urine is performed with apparent ease ; but it will be 

 often seen that the flow suddenly stops, and the further attempts 

 of the animal to empty the bladder prove in vain. He will 

 continue stretched out for a short time ; he may then kick at 

 his beUy, groan, sigh, and perhaps lie down in pain. These 

 results are produced by the calculus being forced into the neck 

 of the bladder, and mechanically arresting the further passage, of 



2s 



