TRACE ELEMENTS IN ANIMALS 139 



that known as Nakuruitis in Kenya (Orr and Holmes, 1931) 

 and that called pining in Scotland (Greig et al. 1933) is 

 another matter. If this should indeed be so it would mean 

 that salt sick results, not from deficiency of copper, but from 

 deficiency of cobalt. The United States Department of Agriculture 

 Yearbook for 1939 records that although surveys were not then 

 complete, observations of cattle indicate a few copper-deficient 

 areas and a considerable cobalt- deficient area in Florida. Thus 

 it may be that both copper deficiency and cobalt deficiency may 

 occur in cattle in that State. The work of Rusoff, Rogers and 

 Gaddum (1937) rather suggests that all the cases of salt sickness 

 may not be due to the same cause. Thus they state that workers 

 at the Florida Agricultural Experiment Station have found that 

 cobalt is a limitixig factor in a type of salt sick known as 'hill 

 sick ' . It would therefore appear likely that this is identical with 

 pining or bush sickness. Rusoff, Rogers and Gaddum, however, 

 were unable to detect cobalt spectrographically in the grasses of 

 either salt-sick or healthy areas, but it may be, as they point out, 

 that this element, as well as others, may be present in quantities 

 too small to be determined by the method used. But as regards 

 copper, they found the same content of this element in the 

 grasses from salt-sick and normal areas, so that their analyses, 

 lend no support to the view that salt sick results from shortage 

 of copper. But, as they point out, it may be that the ratio of 

 various elements is the important factor and that the disease 

 might occur where the iron content of the grass is high and the 

 copper content low, or vice versa, or the ratio of iron or copper 

 to some other element might be the determining condition. 



A disease of lambs which may result from shortage of copper 

 occurs widely in Great Britain, but appears to be most trouble- 

 some in an area of north Derbyshire, in part of the Cheviot Hills, 

 in certain districts of Yorkshire, and in an area of Gloucester- 

 shire and Somersetshire where the Mendip Hills appear to 

 provide the worst cases. The disease also occurs in Australia, 

 while the same or a similar disease has been described as 

 occurring in Sweden, in India and in Peru and other parts of 

 South America. In this country it is known as sway back, 

 swingback or swingleback, and in Australia as enzootic ataxia. 

 In this country it has probably been known to farmers for a very 



