PARASITES AND PARASITIC DISEASES OF HORSES 45 



psoroptic mite. Chorioptic mites live on the surface of the skin and 

 produce lesions similar to those of psoroptic mange. 



The lesions of chorioptic mange are usually confined to the lower 

 part of the limbs around the foot and fetlock. Occasionally the 

 mites spread over the legs above the« hocks, and may reach even the 

 thighs and abdomen, but usually the disease remains localized around 

 the feet. 



Infested animals paw and kick and rub the pastern with the oppo- 

 site foot and often try to bite the affected parts. Some of the hair 

 comes out and the skin has the thickened and hardened condition 

 characteristic of scabies. 



The remedies recommended for sarcoptic mange are effective in 

 eradicating foot mange. The affected areas should be well soaked in 

 warm lime-sulphur clip, and the treatment repeated every 10 days 

 until a cure is effected. Driving the horses through a shallow wad- 

 ing tank filled with dip is a quick and effective method of treatment 

 for foot mange. 



TICKS 



There are many different kinds of ticks which may attack horses, 

 but since the habits and life cycles of the different species vary 

 greatly discussion in this circular is necessarily limited to general 

 information, except for the ear tick, which is discussed more fully. 



When only a few ticks are found on horses they may be removed 

 by hand or covered with crude petroleum, cylinder oil, kerosene, or 

 other oil, which usually causes them to detach and drop to the 

 ground. In removing ticks by hand the writer has observed that 

 they may sometimes be detached without leaving the head embedded 

 in the skin by twisting them around as they are pulled loose. 



In the southern and western parts of the United States it is not 

 uncommon for horses to become grossly infested with ticks. In 

 some sections the infestation may occur only infrequently ; in others 

 it may occur more or less regularly each year. In the region in- 

 fested with cattle-fever ticks where eradication work is in prog- 

 ress tick-infested horses are dipped in arsenical solution to kill the 

 parasites. 



In any locality where the horses become infested with ticks and 

 the infestation is extensive the State livestock sanitary authorities 

 should be notified in order that the ticks may be identified and 

 proper measures taken for control. Control or eradication methods 

 to be successful must be based on a knowledge of the life history 

 and habits of the tick involved. 



SPINOSE EAR TICK 



Nature and habits. — The spinose ear tick (Ornithodoros megnini) 

 is prevalent on horses in the Southwest and causes serious damage to 

 the livestock industry. Spinose ear ticks (fig. 31) enter the ears of 

 animals as small, 6-legged seed ticks and attach themselves in the 

 external canal well below the hair line, where in a week or two they 

 become engorged larvse. The engorged larvae molt to form nymphs 

 or young ticks having eight legs. The young ticks remain in the 

 ears from one to seven months, or until fully grown and engorged, 



