34 CIRCULAR 148. U. S. DEPARTMENT OF AGRICULTURE 



ative. Cases of dizziness have been reported occasionally in horses 

 dosed with tetrachlorethylene, but this dizziness soon passes off. 



Treatments should be administered in the winter after the adult 

 flies are killed by frost and all the bots are present in the stomach 

 or upper part of the small intestine. The best time is about 1 month 

 after the first freezing weather lasting 24 hours or longer. One month 

 before the internal medication an application of one of the coal-tar 

 creosote dips in about 2 percent dilution to the parts of the animal 

 bearing the bot eggs is advised so as to destroy the eggs and thus 

 avoid subsequent infestation. 



Prevention. — Preventive measures against infestation with bots 

 include the use of various protective mechanical devices to prevent 

 the flies from depositing their eggs on horses, shaving the hair where 

 the eggs have been deposited, and the destruction of the eggs by 

 certain medicinal applications to the skin. 



Disposal of Manure 



Inasmuch as manure is the source from which horses acquire nearly 

 all their common parasites, either directly or indirectly, the proper 

 disposal of manure from stables and yards is an essential part of 

 sound management. Indiscriminate spreading of fresh horse manure 

 on horse pastures to supply fertilizer is an unwise and unsafe procedure 

 because it disseminates infective eggs and larvae of parasites which 

 have developed in stables and yards. Owners of thoroughbred horse 

 farms who have learned of the danger to horses as a result of spreading 

 fresh manure on pastures have discontinued this practice and are dis- 

 carding manure as fertilizer altogether. Such a procedure is too 

 wasteful for farm practice, as the manure must be utilized and is safe 

 after it has been stored for a time. Conditions of storage should 

 permit the spontaneous heating process, which is destructive to eggs 

 and larvae of parasitic worms, to act throughout the manure for a 

 sufficient time. 



When manure is stored in open piles it heats in the middle but 

 remains cold on the surface. Such manure is dangerous, so far as 

 parasite transmission is concerned, because the eggs and larvae pres- 

 ent on the surface of the manure pile escape destruction. It is, there- 

 fore, important that the outer 3 or 4 inches of exposed manure piles 

 be turned over every week or so in order to bury the exposed manure 

 under the inner material of the pile and sterilize it by heating. If this 

 is not done, the manure should not be placed on any field to which 

 horses may have access even months later, as the eggs and larvae of 

 many species of parasites are long-lived and very resistant to unfavor- 

 able influences. It has been determined that the eggs and larvae of 

 parasites present in manure can be more certainly and easily destroyed 

 if the manure is stored in closed containers or boxes, having double 

 walls and a double floor, with a 4- to 6-inch space between the walls and 

 floor filled with sawdust and, the top of the container covered with a 

 well-fitted lid (fig. 23). It is essential that the containers be tight 

 in order to retain as much heat as possible; the greater the heat devel- 

 oped and retained in manure boxes the sooner the eggs and larvae will 

 be destroyed. 



