278 DISEASES OF THE SKTN 



Treatment. — ^While the recognition of goitre in the sow is 

 extremely difficult it is recommended that, whenever hairless 

 litters of pigs are born on the farm, the pregnant sows be 

 fed iodin in the form of iodid of potash (10 grams to each 100 

 pounds feed). The iodid of potash should be fed during the 

 entire period of gestation or at least during the last seventy- 

 five days of it. It is also recommended as a prevention to 

 feed plenty of roughage, alfalfa and clover hay. Intensive 

 grain feeding with too little roughage tends to predispose to 

 the disorder. 



ERYTHEMA. 



Definition. — Erythema is an inflammatory congestion of 

 the skin which may be primary and result from various 

 mechanical, chemical, and thermic causes; it may be a symp- 

 tom of eczema, or it occurs secondary to infections and intoxi- 

 cations. In hog-cholera, erythema is occasionally seen; in 

 swine erysipelas it is a constant symptom. White swine and 

 sheep are affected by it if they eat growing buckwheat in the 

 bright sunlight. 



PRURITUS. 



Definition. — By pruritus an itching of the skin without 

 visible lesion is meant. It may be local or general. 



Etiology. — The causes are not well understood. In some of 

 the infectious diseases, such as rabies, dourine, and in dis- 

 orders due to worms like trichinosis and grub-in-the-head of 

 sheep, it has been observed. Severe, general diseases are 

 sometimes accompanied by pruritus, such as chronic nephritis, 

 icterus, and diabetes mellitis. 



Treatment. — Treatment is usually of little avail, and con- 

 sists in the application of local anesthetics or irritants. 



TRICHORRHEXIS NODOSA. 



Definition. — This is a condition of the hair in which nodules 

 occur along the shaft, causing the hair to bend and break off. 



It may affect the hairs of the body or the mane and tail of 

 the horse. As it sometimes occurs enzootically it is probably 



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