964 Licking Disease. 



eontainod in peat liay and which is not known exactly. It occurs 

 in greater quantities in the hay of meliorated meadows than in 

 other meadow hay, is entirely absent in meadow plants before 

 they are in bloom, also in the hay of the first cut before bloom- 

 ing time and in the clover hay of meadows which are otherwise 

 dangerous. The second crop of hay is less dangerous than the 

 first. The poisonous substance is destroyed entirely or par- 

 tially by steaming, heating to 80° C. and during the preparation 

 of "brown hay.'' It has no harmful effects on horses. 



The presumable poison is present in the injurious hay in com- 

 paratively small amounts and therefore it produces gradually increasing 

 disturbances of metabolism through a cumulative action and only after 

 the hay has been fed for a long time. These disturbances cause a 

 defective formation of blood and bone tissue and eventually give rise 

 to a morbid tendency to gnaw and to lick. The elimination of Na, Ca 

 and of P is greater than the intake. 



The chemical composition of Johannisburg peat meadow hay is 

 insufficient also in so far as the hay is poor in Na- and Ca salts and 

 rich in K salts. Although the quantity of the ashes was found in- 

 sufficient, the cause of the disease can, according to Ostertag and Zuntz, 

 not lie in a mineral deficiency of the fodder, because the addition of 

 NaCl, of calcium-, phosphorus- and iron-preparations to the hay did 

 not influence the toxic .action and because this could be destroyed by 

 heating. 



How far the results of Ostertag & Zuntz may be applied 

 to licking disease occurring in other places cannot be determined 

 at present. For those cases, indeed, in which licking disease 

 develops in connection with osteomalacia or simultaneously with 

 this disease, the same causes are probably active. It appears 

 that particularly the deficiency in nutritive salts is of essential 

 importance in this respect. 



As other causes of the disease contagion, heredity, imitation, bad care, have 

 been mentioned. 



From what has been said it is evident that a close relation 

 exists between licking disease and osteomalacia, since in both 

 diseases certain changes in the bones develop under the infln.- 

 ence'of disturbances of metabolism. The most important dif- 

 ference between the two is seemingly that licking disease occurs 

 apparently independently and leads to severe cachexia even 

 before manifest softening of the bones has developed. But since 

 in such cases the bones have not been examined microscopically, 

 the possibility cannot be excluded that changes corresponding 

 to osteomalacia are indeed present, only not in such a degree 

 that the softness of the bones could be determined by the coarser 

 methods of examination; and this is evident from the observa- 

 tions of Ostertag & Zuntz. It is thus thinkable that licking 

 disease actually owes its development to osteomalacia, but that 



