PARASITES AND PARASITIC DISEASES OF HORSES. 45 



Contagiousness. — Each species of domesticated animal has its own 

 peculiar variety of psoroptic mange, and the variety which lives on 

 the horse, ass, or mule is not transmissible to other animals, with the 

 possible exception of the camel. The disease is more highly contagious 

 t o all classes of horses than sarcoptic mange. The predisposing causes, 

 maimer of spreading, carriers of the mites, and precautions to be 

 observed in isolating infected animals and cleaning and disinfecting 

 premises are practically the same as for sarcoptic mange. 



Treatment. — As the psoroptic mites live on the surface of the skin, 

 they are more easily eradicated than the sarcoptic variety. The rem- 

 edies recommended for sarcoptic mange are effective in eradicating 

 this disease. Two dippings from 10 to 12 days apart may usually be 

 depended on to cure ordinary cases. Four or more dippings may be 

 necessary in chronic cases. 



CHORIOPTIC MANGE 

 CHORIOrTTC MANGE MITE 



Chorioptic or symbiotic scabies, commonly known as foot mange, 

 is caused by a mite (Ohorioptes equi) which closely resembles the 

 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 opposite 

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

 out and the skin has the thickened and hardened condition character- 

 istic 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 dip, and the treatment repeated every 10 days 

 until a cure is effected. Driving the horses through a shallow wading 

 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 some- 

 times 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 infested with 



