PARASITES AND PARASITIC DISEASES OF HORSES 



17 



eggs and larvae are largely protected from unfavorable influences and 

 they have an abundant supply of moisture and shade and a favorable 

 temperature for development. It is, therefore, important to pay 

 strict attention to stable sanitation and to remove manure frequently, 

 supply fresh bedding, clean water from sanitary watering troughs 

 (fig. 10), and dry feed in feed boxes and racks well raised above the 

 floor in order to prevent contamination with horse manure and con- 

 sequent gross infestation with these parasites. (Fig. 11.) 



STRONGYLOSES 



Foals are commonly infested with very small and slender thread- 

 worms, Strongyloides wcsteri, which occur in the small intestine. 

 These parasites, all of which are females, are whitish in color, about 



Figure 10. — Type of sanitary watering trough 



one-third of an inch long, and less than one two-hundred-and- 

 fiftieths of an inch wide. 



These threadworms produce numerous eggs, microscopic in size, 

 and deposit them in the intestine of the infested foal from which 

 they are eliminated in the manure. The eggs develop very rapidly 

 on the ground and on pastures, and the larvae which emerge from 

 them may either transform directly into infective larvae which serve 

 to infest other foals, or may develop into free-living males and fe- 

 males. As a rule both types of development take place, some larvae 

 becoming infective while others develop into free-living adults. The 

 latter mate on the ground or in manure and the females produce eggs 

 and deposit them on soil or in manure. In a short time, under 

 favorable conditions, larvae emerge from these eggs. These larvae 

 become infective and are capable of infecting horses. 



51909°— 34 — —3 



