DISEASES OF THE SKIN. 467 



ounce carbolic acid in a pint of water, bound on with cotton wool or 

 lint, may cut them short. The more common course is to apply a 

 warm poultice of linseed meal or wheat bran, and renew daily until 

 the center of the boil softens, when it should be lanced and the core 

 pressed out. 



If the boil is smeared with a blistering ointment of Spanish flies 

 and a poultice put over it, the formation of matter and separation of 

 the core is often hastened. A mixture of sugar and soap laid on the 

 boil is equally good. Cleanliness of the skin and the avoidance of 

 all causes of irritation are important items, and a teaspoonf ul of 

 bicarbonate of soda once or twice a day will sometimes assist in 

 warding off a new crop. 



NETTLERASH (SURFEIT, OR URTICARIA). 



This is an eruption in the form of cutaneous nodules, in size from 

 a hazelnut to a liickory nut, transient, with little disposition to the 

 formation of either blister or pustule, and usually connected with 

 shedding of the coat, sudden changes of weather, and imwholesome- 

 ness or sudden change in the feed. It is most frequent in the spring 

 and in young and vigorous animals (good feeders). The swelling 

 embraces the entire thickness of the skin and terminates by an abrupt 

 margin in place of shading off into surrounding parts. When the 

 individual swellings run together there are formed extensive patches 

 of thickened integument. These may appear on any part of the 

 body, and may be general; the eyelids may be closed, the lips ren- 

 dered immovable, or the nostrils so thickened that breathing becomes 

 difficult and snuffling. It may be attended with constipation or 

 diarrhea or by colicky pains. The eruption is sudden, the whole 

 skin being sometimes covered in a few hours, and it may disappear 

 with equal rapidity or persist for six or eight days. 



Treatment. — This consists in clearing out the bowels by 5 drams 

 Barbados aloes, or 1 pound Glauber's salt, and follow the operation 

 of these by daily doses of one-half ounce powdered gentian and 

 1 ounce Glauber's salt. A weak solution of alum may be applied to 

 the swellings. 



PITYRIASIS, OR SCALY SKIN DISEASE. 



This affection is characterized by an excessive production and 

 detachment of dry scales from the surface of the skin (dandruff). 

 It is usually dependent on some fault in digestion and an imperfect 

 secretion from the sebaceous glands and is most common in old horses 

 with spare habit of body. Williams attributes it to feed rich in sac- 

 charine matter (carrots, turnips) and to the excretion of oxalic acid 

 by the skin. He has found it in horses irregularly worked and well 



