912 DISEASES AND THEIE TBEATMENT. 



after either of these medicines. Nearly all parasites in horses 

 can be expelled by the judicious use of calomel. 



BOTS. 



As among most owners and horse-doctors, every obscure lame- 

 ness in the foot is supposed to be in the shoulder ; so, when a horse 

 is taken sick, nine times out of ten it is supposed to be caused by 

 bots. If the horse turns up his upper lip, looks at his side, shows 

 uneasiness, paws, and rolls, it is taken as a sure sign of bots. 



It is claimed that as a rule bots are harmless parasites, seldom 

 producing much mischief, and to be found in almost every horse 

 that dies, sometimes in great numbers, adhering to the coats of 

 the stomach ; but about this there is much difference of opinion. 



Prof. Law on the subject: 



' Bots are the larva of the gadfly, which are noticed to be so 

 common, pestering the horse during the summer and autumn, dart- 

 ing at him around his legs and sides, and depositing their eggs on 

 the hair of the parts. These eggs are caught by the horse when 

 he licks the parts in defending himself, and swallowed. In the 

 stomach they develop rapidly. By the aid of the hooks around 

 their heads they attach themselves to the mucous membrane mainly 

 of the loft half of the stomach (See Fig. 800), but often also to other 

 parts, euch as the right side of the stomach, the duodenum or small 

 gut leading from the stomach, and the throat. There they cteadily 

 grow in the winter, and in spring pass out in the dung, burrow in 

 the eoil, and are transformed into the gadfly. The disturbance they 

 cause depends on their numbers and the portions of the canal on 

 which they attach themselves. In the throat they produce a 

 chronic sore throat and discharge from the nose, which continues 

 until the following spring, unless they are previously extracted 

 with the hand. In the left half of the ctomach, which is covered 

 with a thick, insensible cuticle, they do little harm when in small 

 numbers; hence Bracy Clark supposed them to be rather beneficial 

 in stimulating the secretion of gastric juice. 



"When very numerous, and above all, when attached to the 

 highly sensitive right half of the stomach or the duodenum, they 

 seriously interfere with digestion, causing the animals to thrive 

 badly, to be weak, and easily sweated or fatigued, and even deter- 

 mining sudden and fatal indigestions. This last result is especially 

 liable to occur in spring or early Bummer, when the bots are pass- 

 ing out in great numbers, and hooking thomselves at intervals to 

 the coats of the sensitive bowela in their course. They will some- 

 times accumulate in such numbers as actually to block the pas- 

 sage." 



