724 DISEASES OF THE SKIN. 



that the animals do not lick themselves for some time after tlie 

 remedy is applied. 



Debility seems to be the predisposing cause, rendering the 

 animal a proper habitat for the propagation and development 

 of these parasites. It must be overcome by good food, tonics, 

 and cleanliness. 



One form of lousiness in the horse deserves special mention, 

 namely — 



POULTRY LOUSINESS, OR RIITHIRIASIS EQUL 



Attention was first drawn to this disease by Professor Bouley, 

 whose observations are published in the Veterinarian for April 

 1851. He says — " Its commencement is instantaneous. All 

 at once the horse is seized with violent itcliing. So sudden and 

 irresistible is the desire the animal possesses to scratch himself, 

 that he is not easy for a single moment. He rubs his sldn 

 against every resisting body near liim, stamps the ground con- 

 tinually, strikes Ms belly, bites every place he can reach with 

 his mouth, manifesting by his continual movements the burning 

 itching by which he is devoured. At night his torments increase, 

 so much so, that should the animal be abandoned to himself, he 

 rubs and bites himself to that degree that he tears his skin, and 

 carries portions away in his mouth, denuding himseK extensively 

 of his scarf-skin ; nor does he relax until smarting pains succeed 

 the insupportable torments of the itching." 



The itchiness is accompanied by an eruption of very small 

 vesicles on the skin — some solitary, others in greater number, 

 occupying more or less extent of surface. These are succeeded 

 by depilation of the epidermis and hair, leaving a small, perfectly 

 circular, bare surface, of the size of a lentil or the smallest silver 

 coin. The formation of these circular spots by consecutive des- 

 quamations goes on rapidly ; in a few days a horse with the most 

 shining coat may be spotted over with circular patches, devoid of 

 hair, and in the course of a week the hair and epidermis will be 

 destroyed over a large extent of surface. 



The disease does not seem to interfere with the general func- 

 tions, and, apart from the violent itchiness and excitement which 

 the animal experiences, he appears in perfect health. " When, 

 however," says M. Bouley, " the disease becomes of long duration, 

 the subject of it will be apt to fall off in his appetite, to grow 



