PARASITES AND PARASITIC DISEASES OF HORSES 53 



percentage of gas in the air cannot be raised to more than about 1.5 or 

 2 percent by burning sulfur in the gas chamber unless special appa- 

 ratus is installed. Sulfur dioxide compressed to a liquid and stored 

 in steel cylinders is available on the market. By using the compressed 

 gas any desired concentration in the chamber within certain limits 

 may be obtained. In winter, when the temperature is too low for 

 dipping, fumigation is feasible if a large number of horses are to 

 be treated and competent men are available to supervise the work. 

 This method apparently has no other distinct advantage over dipping. 



DIPPING 



Dipping is the most effective known method of applying treatment 

 for common external parasites. Dipping plants are so arranged that 

 the animals are immersed in liquid deep enough to swim in, and the 

 entire body surface is well soaked. For dipping horses the dip in the 

 vat should be kept at a depth of 70 to 80 inches, or sufficient to immerse 

 completely the tallest animal to be dipped. Horses wdl carry out and 

 retain from 2 to 4 quarts of dip each, and the depth of the liquid in 

 the vat will be lowered accordingly. The total estimated quantity 

 of dip which the animals carry out plus that required to charge the 

 vat should equal the total quantity required, provided none is lost by 

 leakage or otherwise wasted. 



The capacity of the vat is usually obtained by multiplying, in terms 

 of inches, the average length by the average width, then the product 

 by the depth. This gives approximately the number of cubic inches 

 of space to be filled with dip. Divide this by 231 (the number of 

 cubic inches in a gallon), and the result will be the number of gallons 

 of dip needed to charge the vat. 



To obtain the average length, add the length at the bottom to the 

 length at the dip line and divide by 2. The average width is obtained 

 in the same manner. The depth should be taken at the center of the 

 vat and from the bottom to the dip line only, and not to the top. 

 All measurements should be made only of the space to be filled with 

 dip, and not above the dip line. The capacities of the various tanks 

 are obtained by like process. 



Before dipping, the contents of the vat should be well stirred, in 

 order that the dip may be of uniform strength and temperature 

 throughout. The pens, chutes, vat, etc., should be examined for 

 projecting nails or any object that might puncture or wound the 

 horses, as the dip may injure those having fresh wounds. 



In dipping wild range horses it is necessary to have a gate or bar 

 in the chute to prevent the animals from piling up in the vat. Horses 

 should be watered and fed from 2 to 4 hours before dipping, and if 

 heated by driving they should be allowed to cool off before entering 

 the vat. 



The head of each animal should be completely submerged for 

 an instant at least once while in the vat. The head should not 

 be held under, but quickly ducked with a dipping fork and released. 

 Two duckings of the head are advisable, especially if the animals are 

 affected with scabies. Care should be taken to see that the inner 

 surface of the ear is well soaked. 



