326 Veterinary Medicine. 



supply this. It has been noticed that army horses in the field, 

 feeding from the ground and taking in sand and pebbles, are un- 

 usually liable to intestinal calculus. Horses which lick earth in 

 connection with acidity of the stomach or other dyspepsia are 

 specially subject to it. Honses watered from shallow streams with 

 sandy bottoms, where they take in sand with the water, have been 

 similarly affected. Millers' horses, in the days of old process 

 milling, suffered not alone because of the abundance of oat hairs 

 in the feed but also on account of the grit from the millstones. 

 Hay and other fodders that have lain on the' ground and which 

 contain earth and sand furnish other sources of such nuclei. 

 Shingle nails and other small nails, pins, needles, coins, etc., 

 which have mixed with the feed are common causes of trouble, 

 and indeed any foreign body may become the centre and starting 

 point of a calculus. 



Catarrhal affections and other lesions of the mucosa, which 

 furnish excess of mucus, beside pus, lymph and even blood as 

 nuclei, are invoked as .starting points of the calculi, but however 

 true this may be in particular cases, irritation and catarrh appear 

 to be much more frequently the result than the cause of the 

 calculus. 



Attempts have been made to estimate the time taken in the 

 formation of a calculus by allowing a ring for each feed and suc- 

 cessive deposit therefrom (Fiirstenberg, Colin). Thus a calculus 

 of 14 pounds with 720 layers, it was estimated could be formed in 

 one year at two feeds per day. More definite evidence was found 

 in the case of Pastore in which a coin with the mint mark of 1847 

 was found as the nucleus of a calculus the size of the fist in 1848. 



Lesions. Formed in the most spacious parts of the colon and 

 caecum, calculi usually rest there for a length of time without 

 visible injury, and it is only when they are moved onward and 

 get arrested at a narrow part of the gut (pelvic flexure, floating 

 colon, rectum) that they cause appreciable trouble. Yet it is 

 claimed that by their weight they drag upon the yielding walls of 

 the bowel, causing dilatation and attenuation, weakening the 

 peristalsis and predisposing to rupture. The compression of the 

 vessels also tends to anaemia and atrophy. In the ca.se of rough 

 crystaUine calculi the mucosa is subjected to attrition, irritation, 

 and inflammation. The more serious and urgent trouble is that 



