PARASITES AND PARASITIC DISEASES OF HORSES 17 



Experimental investigations indicate that carbon tetrachloride is 

 also effective for the removal of ascarids. The animal should be 

 fasted 18 hours and the carbon tetrachloride given in doses of from 6 

 to 12 fluid drams (25 to 50 cubic centimeters) for a 1,000-pound 

 animal. This drug usually need not be accompanied with a purgative, 

 but it is advisable to give a saline purgative immediately following the 

 administration of carbon tetrachloride for the removal of worms, 

 particularly ascarids, from colts. The saline purgatives, magnesium 

 sulfate (Epsom salt) and sodium sulfate (Glauber's salt), are ordi- 

 narily administered to young animals in doses of one-half pound or 

 less, and to mature animals in doses up to 1 pound. 



Prevention. — Prevention of ascarid infestation requires special care 

 of foals and young horses. The time to begin is before the foal is 

 born. The foaling barn should be of sanitary construction and should 

 be cleaned and washed with hot water and lye before the pregnant 

 mare is placed in it. The mare and foal should be kept in a clean 

 paddock adjoining the barn. It is best to use a paddock from which 

 other horses have been absent for at least a year. The stable and 

 paddock in which the mare and foal are kept should be cleaned daily 

 if possible, litter and manure being removed. 



These precautions are designed to prevent the foals from becoming 

 heavily infested with ascarids at an early age, and before they have 

 developed the necessary reserve vitality to cope successfully with a 

 heavy worm infestation. When the foal is moved to a pasture it is 

 essential to select one which is clean and that has not been used by 

 horses for a year or longer. Proper disposal of manure and sanitary 

 measures recommended in connection with the control of blood 

 strongyles will also help to prevent infestation with ascarids. 



While infestations with ascarids can be acquired on pastures, and 

 often are so acquired, it is important to remember that ill-kept stables, 

 in which manure is allowed to accumulate (fig. 9) , are also the sources 

 of heavy infestations with intestinal roundworms, pinworms, and other 

 threadworms. Under pasture conditions many eggs and larvae 

 succumb to drought and to other unfavorable influences which prevail 

 in the open. In manure-laden stalls parasite 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 consequent gross in- 

 festation with these parasites (fig. 11). 



STRONGYLOSES 



Foals are commonly infested with very small and slender thread- 

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

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

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

 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 



811770° — 49 3 



