PARASITES AFFECTING THE SKIN Ir 
crusts. Pruritus becomes more intense, and, unless 
treated, the animal may lose condition through the 
continuous irritation and loss of rest. To diagnose with 
any degree of certainty a microscopical examination 
must be made, and the parasites discovered. 
The method of procedure is as follows : Find a recent 
lesion which has not been dressed with a parasiticide, 
remove all scabs, and scratch the surface exposed with 
a scalpel until bleeding is produced. It is advisable, 
some while before commencing, to have the animal 
stood in sunlight, as this increases the activity of the 
parasites, and brings them nearer the surface. The 
scales of epithelium, portions of hair and_ blood, 
thus procured are placed in a shallow watch-glass, 
covered with a little diluted liq. potasse, and allowed 
to stand for about five minutes, in order to dissolve the 
fat. The scrapings are then placed on a glass slide as 
thinly as possible, and covered with another of the same 
thickness. The two slides are then held between the 
finger and thumb of each hand, and each is gently moved 
about upon the other. This distributes the epithelial 
scales, and on examining with a 1-inch objective, there 
should be little difficulty in detecting the parasites, if 
present, in the scrapings. Time and a great deal of 
patience are necessary, and care must be taken to scrape 
deeply, more especially when examining for Sarcoptes. 
If the scabs are exposed to strong sunlight for an hour 
before examining, the mites will come to the surface, 
and are more easily demonstrated. 
In the case of Acari in the external ear, it is only 
necessary to treat the wax obtained as described. 
The presence of the Demodex folliculorum is not 
difficult to demonstrate, providing a fresh pustule is 
discovered. This should be pricked with a fine needle, 
and the contents squeezed out and placed on a glass 
slide. No alkaline treatment is necessary. 
