Diagnosis of Skin Diseases. 461 



2d. Make the examination in a clear day in full- sunshine if 

 possible. In dark, cloudy weather, and in dimly lighted stables 

 it is impossible to identify the different lesions. Artificial light 

 is very unsatisfactory. Warmth, as in sunshine, or in a warm 

 day or room, increases any itching and the cutaneous circulation 

 and congestion, and renders more- lively and active the animal 

 parasites that may be present. These may be found in the 

 surface scrapings taken in warmth, and not at all if taken in 

 cold. A hand lens will assist in the discovery of the larger 

 parasites, while for the smaller ones the microscope must be 

 employed. 



3d. Examine carefully all parts of the skin and even the 

 visible mucosae, estimating whether any lesions of the latter in- 

 dicate extension from the skin, by proximity, or a general 

 constitutional affection. Scrutinize particularly such parts as 

 have not been abraded by mechanical injury — those which show 

 the primary character of the lesion. Is the afEected portion of 

 the skin dry or moist ? Some eruptions like impetigo or grease, 

 are always moist, others like pityriasis or dry eczema are habit- 

 ually dry apart from mechanical injuries. Ascertain the color, 

 odor and consistency of any discharge. It may be a limpid or 

 reddish serum in grease, honey-like in impetigo, oily in farcy, 

 greasy in swine-plague. The odor is foetid in grease, canker 

 and thrush of the frog, cheesy in variola, and mousy in favus. 



4th. To learn the true nature of the eruption a warm, soapy 

 wash may be essential to remove scurf, scab, and other encrusta- 

 tions. 



5th. . Note the depth and extent of the skin lesions, the thick- 

 ening of the skin, its pliancy or rigidity, its adhesions to subja- 

 cent parts or free movement upon them, whether it is contracted 

 into folds or ridges, the degree of congestion, the nature of the 

 eruption, uniform congestive redness, papule, vesicle, pustule, 

 squama, sore, ulcer, nodule, slough, etc. Are the individual 

 lesions isolated or confluent ? 



6th. The presence of itching and its degree are important data. 

 Pruritus is always excessive in ordinary acariasis, marked in 

 eczema, phthiriasis, and some neuroses, and very slight in a 

 number of skin affections (pityriasis, ringworm', grease, thrush, 

 contagious acne). The abrasions and sores caused by rubbing. 



