PARASITES AND PARASITIC DISEASES OF HORSES 17. 
eggs and larve 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.) 
STRONGYLOIDES: 
Foals are commonly infested with very small and slender thread- 
worms, Strongyloides westert, 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 larve which emerge from 
them may either transform directly into infective larve which serve 
to infest other foals, or may develop into free-living males and fe- 
males. Asa rule both types of development take place, some larve 
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, larvee emerge from these eggs. These larve 
become infective and are capable of infecting horses, 
153249°—33 
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