MANGE OF THE HORSE. 



65 



organ. The adult animal has eight legs, the young six. 

 The roundish male has one fine claw on the first two pairs 

 of legs, two larger ones on the third, and none on the fourth 

 and last. The mites moult four times. 



This genus contains a single species, the Psoropte.s com- 

 Tnunis Fuerst. Besides the characters already given for the 

 genus it is only necessary to state that it also occurs in num- 

 erous forms upon a number of domesticated animals, upon 

 which'lit causes crusts by pricking their skins. The differ- 

 ences between these forms or varieties are not great, but suf- 

 ficiently so to give them each a name according to the host 

 upon which they occur. 



THE COMMON MANGE OF THE HORSE. 



{Psoroj)tes communis var. equi). 

 This disease caused by parasitic mites is the most 

 common and longest known of all skin-diseases of the horse, 



ass and mule. It can appear upon 

 any part of the body except the ex- 

 tremities of the limbs, but it is most 

 usually found upon the upper part of 

 the neck, the root of the mane, the 

 poll and the tail. The mites live in 

 colonies on the surface of the skin, 

 hiding under the shelter of hairs, and 

 their presence is readily discovered. 

 Fig. 37 show^s the two sexes of this 

 mite. If we take some scabs from the 

 Fig. 37.— Mange-mi.es of^^-^^^^^^ parts and put them upon 



riorse;male and female. Great- x' x^ f 



ly enlarged. After Meguin. black papCr, WC CaU CVCn with the UU- 



aided eye see numerous mites moving about actively in all 

 stages of growth. The mites, in feeding upon the surface 

 of the skin, make punctures, and these soon form a crust, 

 and as the parasites multiply rapidly they cause before long 

 similar symptoms to those produced by the true burrowing 

 itch-mites. The constant irritation caused by their presence 

 forces the horse to the most energetic rubbings, which add 

 to the inflammation of the skin, and the sores and ulcers 

 thus produced are often impregnated with blood. 



