ECZEMA. 



515 



consider this dermatosis as a toxic exanthema similar to those pro- 

 duced by certain drugs (to mercurial eruption, for instance), and 

 due to the action of a poisonous matter contained in potato residues, 

 perhaps in the tuber and stalks. 



Affected animals. Malt or residue eczema has been known 

 for more than half a century. Its appearance is contemporaneous 

 with the introduction of large potato distilleries and the extension 

 of the culture of this plant which took place at that time. Spinola, 

 who observed it for the first time in 1827, gave a good description 

 of it in 1836. 



It is found to exist especially in oxen and bulls which are being 

 fattened ; it is less frequently observed in heifers ; milch cows gen- 

 erally escape it. While certain animals seem predisposed to it, 

 others possess a true immunity. The gravest cases are observed 

 in the spring and the beginning of summer, at the period of the 

 year when the potato has reached its maximum growth. 



It is found to be particularly intense in animals recently intro- 

 duced into stables where the trouble exists ; it is most frequently 

 observed in establishments where the cows are often renewed ; here 

 new milch cows may be affected. In the greater number of cases 

 it is localized on the hind legs, where it ascends as far as the hock ; 

 in others it affects exclusively the forelegs ; the four members are 

 sometimes affected at the same time ; exceptionally it is located 

 upon other parts of the body — for instance, on the ribs, back, neck, 

 shoulders, etc. Care, hygiene, and the exposure of the stable have 

 no great influence on its appearance ; it may be recognized on model 

 farms which are perfectly kept and where the animals are subject 

 to the greatest care. 



Etiology and pathogenesis. This eczema is generally the 

 consequence of alimentation with potato residues. Those from rye 

 and Indian corn are inoffensive ; the same must be the case with 

 beer residues, although these have been incriminated by some 

 authors. Its intensity is usually in proportion to the quantity of 

 residue which enters into the ration. Exclusive feeding with malts 

 or a large ingestion of these (80 litres daily per head) will be sure 

 to produce it when at the same time but little dry feed is given. 

 Forty litres of malt per day are sufficient to produce it in some 

 animals, but its course is then ordinarily benign. Residues coming 

 from germinating potatoes or those in advanced fermentation are 

 particularly dangerous. Their harmfulness, which is more or less 



