PARASITES AND PARASITIC DISEASES OF HORSES 51 



In all cases where ear-tick infestation is suspected the animals should 

 be examined, and if no ticks are visible the ears should be probed. A 

 convenient and effective instrument for probing the ears, removing 

 ticks from the ear canals, and breaking down masses of ear wax and 

 ticks may be made from a piece of ordinary bailing wire, as shown in 

 figure 32, the loop end being used for dislodging the ticks. 



Treatment. — A widely used remedy for ear ticks consists of a mixture 

 of two parts by volume of ordinary pine tar and one part by volume 

 of cottonseed oil. In mixing the ingredients add the cottonseed oil 

 to the pine tar and stir until a uniformly smooth mixture is obtained. 

 When necessary the ingredients should be warmed before mixing, so 

 that they will mix readily and flow freely. The mixture remains 

 uniform without separation or deterioration, and may safely be used 

 on any species of domesticated animal. About one-half ounce of the 

 material should be put into each ear, and the ear should be held 

 upright for a few seconds and manipulated to force the material into 

 the deeper parts. 



Other substances have been used, sometimes with good results. 

 Chloroform, for example, either undiluted or mixed with a bland oil, 

 is effective, but substances of this nature evaporate rapidly and 

 therefore afford no protection against reinfestation. 



The use of pyridine in a nondrying adhesive smear has been re- 

 cently recommended. The formulation used is known as " Stock 1029." 

 This formulation has been tested chiefly in cattle, although there can 

 be little doubt that it possesses a useful application to horses as well. 



Another comparatively new remedy possessing effective action 

 against ear ticks, although lacking extensive trials in horses, contains 

 benzene hexachloride as the active ingredient. Under experimental 

 conditions, preparations consisting of 5 percent of this insecticide in 

 pure pine oil, or in emulsifiable petroleum oil, have offered promise of 

 being superior to any of the aforementioned remedies. On account of 

 the variable content of active irisecticidal material in benzene hexa- 

 chloride, it is probable that the best formulations for the purpose 

 described will be found in preparations that are marketed or recom- 

 mended specifically for the destruction of ear ticks when the treat- 

 ment shall have progressed beyond the experimental stage. 



Complete eradication of spinose ear ticks is difficult on account of 

 the habits of the ticks, their great vitality, and the wide range of 

 animals which they infest. Moreover, most horses oppose the in- 

 sertion of anything into their ears. Some form of restraint is almost 

 always necessary if treatment is to be given effectively. Farm horses 

 can usually be controlled with a twitch or by other common methods 

 of restraint, but special equipment is usually necessary for treating 

 range animals. An ordinary crowding chute not more than 3 or 4 

 feet wide is suitable for treating most horses for ear ticks. 



The only known effective method of applying treatment for the 

 destruction or eradication of ear ticks is to insert the remedy into the 

 ear passages by hand. This can be done by means of ordinary metal 

 or hard rubber syringes, cut-down oilers, small paint brushes, or 

 properly equipped knapsack sprayers. Mixtures should flow freely 

 and be applied in such manner as to insure complete coverage of the 

 deep convolutions and the inner surface of the outer ear. The mate- 

 rial should uot be permitted to overflow, since some of the substances, 



