Buckwheat Rash. Etiology. §73 



(a) Buckwheat Rash. Fagopyrismus. 



Buckwheat exanthema is a skin disease occurring from the 

 simultaneous effects of buckwheat and sunlight; according to 

 the intensity of these factors it may occur either as a simple 

 redness of the skin or, as a more or less intense inflammation, 

 which may even lead to necrosis of the skin. 



Occurrence. The disease is found chiefly in sheep ; swine, 

 cattle and goats being attacked much less often, and horses 

 only exceptionally. Only white or white spotted animals are 

 affected. The disease appears only in certain years and in 

 certain localities (Dammann). 



Etiolog-y. The cause of the disease is found in the inges- 

 tion of l)uckwheat {Haidekoni; Polygonum fagopyrum and P. 

 persicaria). The green flowering plant is most dangerous, but 

 the grain, the straw, the chaff and the bran may also produce 

 the disease. The eating of buckwheat fodder alone will not 

 cause the disease, the effect of sunlight on the white or white 

 spotted parts of the skin being also requisite. 



The immediate cause of the skin affectiou is not yet known, and it is not 

 even possible to offer an entirely satisfactory explanation why the combined in- 

 fluence of the buckwheat fodder and of the sun rays is always necessary to produce 

 the disease and why the feeding- of the same material is harmless for black animals 

 and for the black portions of the skin. Experience has shown that both black 

 animals and animals that were dyed black remained free from the disease, as did 

 also the pigmented portion of the skin of spotted animals, and that white animals 

 whose hide was covered by dust and dirt were affected less severely, other things 

 being equal. On the other hand, it has also been observed that buckwheat fodder 

 usually is not effective even in white animals if it is given in cloudy weather, in 

 winter or in the barn. It is not necessary for the occurrence of the eruption that 

 the animals should be exposed to the action of sunlight at the same time that they in- 

 gest the buckwheat fodder ; cases have been observed in which the disease followed the 

 exposure to sun rays in 3 to 4 weeks after a copious ingestion of such food. 

 The combined action of buckwheat and sunlight was recently determined experi- 

 mentally on white mice and guinea pigs by Ohmke, who found that buckwheat loses 

 its injurious effect by extraction with alcohol and that the extract exerts a toxic 

 effect upon white animals on exposure to sunlight. 



Dammann believes that the cause of the disease is found in certain fungi in 

 the buckwheat which come in contact with the skin and which injure the unpig- 

 mented parts of the skin, either themselves or through their poisonous products. 



Pathogenesis. Buckwheat food evidently contains poison- 

 ous substances which may develop in the plant itself under cer- 

 tain conditions of soil or through the influence of microorgan- 

 isms. The experiments of Ohmke do not eliminate the correct- 

 ness of the view that poisonous substances form in the digestive 

 canal after the ingestion of infected food and then are absorbed, 

 just as are those that may be present in the fodder. According 

 to Schindelka, the affection of the skin is produced by toxins 



