The Cause and Prevention op Lamziekte. 23") 



that ou some very bad pica farms lamziekte was unknown. The hone 

 paradox was not suspected — that the giving of sweet bone meal merely 

 prevented the ingestion of toxic veld bones. The second link, the 

 toxicogenic saprophyte, was not surmised. 



Furthermore, the psychological circumstance, referred to above, 

 obscured the truth ; the circumstance that farmers, and indeed most 

 veterinary surgeons who were aware that even European cattle some- 

 times '' ate the washing olf the village green," took no notice of mild 

 bone chewing", but regarded it as normal, and treated it rather as a 

 harmless pastime indulged in by the cattle to pass eternity upon an 

 uninteresting veld. This led to the constant reiteration that lam- 

 ziekte occurred independently of pica. Obviously, if this had been 

 true, and lamziekte and pica each occurred independently of one 

 another, there could be no fundamental relation between the two 

 diseases. 



It was not until the real nature of lamziekte, as a special kind 

 of ptomaine poisoning, had been grasped, and the chain of causation 

 visualized as a whole, that the full distinction between a natural 

 predilection for a sweet bone and a genuine abnormal craving', became 

 apparent. Once the idea of the toxicogenic saprophyte was brought 

 in as etiological link, it became obvious that although pica could, 

 quite well occur without lamziekte, and lamziekte perhaps occur 

 accidentally (as it does experimentally) without pica, lamziekte could 

 only occur as an enzootic and epizootic disease in areas where pica 

 w'as fairly pronounced. 



This led to the necessity of introducing into our Avork some 

 system of ineasunng craving on a quantitative basis, so as to be able 

 to distinguish between the comparatively normal and the definitely 

 abnormal, and express both the degree of pica and the prevalence of 

 pica on some definite chartable basis. This w-as done by utilizing 

 bones at vaiying stages of decomposition. It Avas found quite easy 

 to pick a stinking bone wliich only those animals showing a very 

 marked, craving would touch and a perfectly bleached sweet bone 

 whioh practically every animal would chew, or at least toy with. 

 Intermediate degrees of craving could be identified by intermediate 

 bones, but since this was cumbersome for routine testing of cattle, 

 only two grades of bone were actually adopted — " sweet or bleached " 

 and " distinctly rotten." The latter were picked out as veld bones 

 which would produce lamziekte if drenched in sufficient amount, but 

 were then sterilized to render tlieni non-toxic. The former were 

 selected so as to be quite unobjectionable to anj' beast which showed 

 any clearly defined craving at all, but to be sufficiently objectionable 

 to the real normal non-era ver. 



In measuring craving, a very simple method of routine testing 

 Avas adopted. Two sets of troughs, placed at opposite ends of a large 

 enclosure, were provided with test bones, one with the sweet and 

 the other with the sterilized rotten. The cattle to be tested were 

 admitted first to the rotten bones. The number Avhich picked and 

 chewed these was noted and recorded as ''inarked cravers." Those 

 which refused to touch the rotten bones were then admitted to the 

 sweet bones, and the number which picked and chewed again noted. 

 These were recorded as "mild cravers." The remainder which, by 

 the way, would still usually take a ration of sweet bone meal if 

 peered, Arere entered up as '' uon-cravers." 



