RICKETS. 



179 



the ground with 

 the affected 



a peculiarly ludicrous manner, the sternum almost touching the 

 ground. In foals and calves, the shafts of the metacarpals are 

 the first to give way, the curvatures being from within out- 

 wards; thus the knees are thrown outwards, and the toes 

 drawn inwards. At the same time, the articulations and ex- 

 tremities of the bones become enlarged, hot, and painful ; caus- 

 ing so much lameness that 

 the little animal merely 

 touches 

 the toes of 

 limbs. 



When the bones of the 

 posterior extremities are 

 affected, the toes are turned 

 outwards, the hocks in- 

 wards ; the points of the 

 calci almost touching each 

 other; the animal being 

 what is termed " cow- 

 hocked," the metatarsals 

 at their middle being 

 bent inwards and rather 

 backwards. Writers on 



human surgery say the 

 Figs 29 and 30 illustrate the bent condition ^^^^^ ^^^ ^^^^ laterally 

 of the humerus m rickety dogs. ^ -^ 



by the action of the 

 muscles, and in such cases they are always bent to the side 

 on which the muscles act most powerfully. This holds 

 good in the case of the humeri of dogs, wherein it will 

 be found that the inferior extremities of those bones are pulled 

 upwards and outwards — as in specimens 29 and 30 — and 

 the lower third of the shafts curved inwards, the curvatures 

 being so great as almost to bend the bones completely upon 

 themselves. 



In rickets, not only is there a deficiency of the inorganic 

 elements of the bones originally — namely, the phosphate and 

 carbonate of lime — but there is a want of power to assimilate 

 these salts ; for during the progress of the disease there is 

 inordinate excretion of them from the system, as shown by 

 deposits in the urine. The structure of the bones is soft, 



Fig. 30. 



