MANGrE. 139 



until we draw blood, and gently heat the crusts thus collected before 

 a fire or in the sun. We may examine on a glass plate a small 

 amount of this dust by direct light by means of a microscope magni- 

 fying 40 or 50 diameters. Warmed by sunlight, the insects can 

 then be seen moving about. If we wish to examine them more 

 carefully, we may remove specimens from the dust by the point of 

 a needle, put them on a drop of glycerine on another glass, place 

 over them a covering glass, and put them under a microscope mag- 

 nifying from 150 to 500 diameters. Or we may place the warmed 

 crusts on black paper and examine them with a strong magnifying 

 glass, which will be sufficient to show us any psoroptes or symbiotes 

 that may be present. Or we may soak the crusts for a couple of 

 hours in a ten per cent, solution of caustic, potash, which by its 

 power of dissolving albumin w411 free the insects from the debris 

 with which they are surrounded, and then put the now colourless 

 crusts under a cover glass. 



Sarcoptic mange may be mistaken for that due to poultry mites ; 

 and vice versa. 



TREATMENT OF THE VARIOUS KINDS OF PARASITIC 

 MANGE. — Here, our first object is destruction of the parasite. In 

 using applications for that purpose, we must guard against irritating 

 the skin too much ; producing symptoms of poisoning by absorp- 

 tion ; and injuriously interfering w^ith the function of the skin, 

 which we might do by covering too large a surface with oily or 

 fatty matters. Our treatment of an invasion of sarcoptes should 

 extend over the whole surface of the body, on account of the roving 

 habits of these insects ; but not more than half of the body should 

 be dressed at one time. Unless the coat is short, we should in all 

 cases clip the horse (generally, for the sarcoptes ; locally, for the 

 other two). In psoroptic mange, as recommended by Nevmiann, 

 we might, in order to disfigure the animal as little as possible, clip 

 the hair of the affected parts of the mane only in the furrows of 

 the wrinkled skin ; and make transverse openings through the hairs 

 of the tail to facilitate cleaning and dressing the part. If this 

 clipping cannot be done on some unfrequented spot, so that the 

 insects may not have the chance of making a fresh invasion, the 

 removed hairs should be collected together and burnt. Our next 

 care should be to expose the parasites as much as possible to the 

 action of the agent w^e intend employing for their destruction, by 

 washing the parts thoroughly, which we may do by rubbing soft 

 soap into them, and then scrubbing the surface wath a brush and 

 warm water, to which we may with benefit add a quarter of an 

 ounce of carbonate of potash to the quart of water. As an external 

 application we might advantageously use any of the following : — 



