CHAPTER IV. 



ANIMAL PARASITES IN THE STOMACH. 

 HELMINTHIASIS. 



GASTROPHILUS. BOTS. 



Varieties. — ^The larvse of botflies occur in the stomach 

 and bowel of the horse. The following varieties have been 

 described: (a) Gastrophilus equi, which is usually found 

 in the esophageal portion of the stomach, (b) Gastrophilus 

 pecorum, found in the stomach, duodenum and rectum 

 (Hungarian and Russian horses), (c) Gastrophilus hemor- 

 rhoidalis, found in the pyloric portion of the stomach, 

 duodenum and rectum, (d) Gastrophilus nasalis, found in 

 the pyloric portion of the stomach and duodenum. 



Life History. — ^The female botfly, which is common in 

 summer, flying over the pasture fields and roads, deposits 

 her eggs on the skin of the horse, especially on the hairs of 

 the front legs, mane, neck and about the nose and mouth. 

 In from three to five days there issue from the eggs the 

 larvse, which are licked off by the horse, reach the stomach, 

 where they attach themselves to the mucous membrane, 

 to remain until the following spring. In the months of 

 May to July, and sometimes during the later summer, the 

 bots leave the stomach, pass into the intestines and are 

 voided with the feces. Either on the ground or in the 

 manure they change into the chrysalis stage. In about 

 one month the mature fly emerges, and after copulation the 

 females deposit their eggs as described. 



The gastrus larvse are found in the stomach of all horses 

 on pasture, in small towns or where the botfly appears. 

 Generally speaking, the larvse are harmless. Only in very 

 exceptional cases do they cause illness through traumatic 

 gastritis. In still rarer instances they produce perforation 



Digitized by Microsoft® 



