360 DISEASES OF METABOLISM 



solution or absorption of the lime salts, (c) Digestive 

 disturbances (gastric and intestinal catarrh) reduce the 

 amount of lime salts absorbed by increasing the normal 

 elimination of calcium compounds from the intestines. In 

 young animals this condition often occurs at the time of 

 weaning when the character of the food is suddenly changed. 

 (d) Inflammatory conditions of the bones in which the blood- 

 vessels are enlarged and the circulation increased preventing 

 the depositing of the lime salts in the new bone tissue. This 

 process keeps the lime salts in solution instead of being 

 deposited in their normal manner, (e) The possibility of 

 infection having to do with the production of rachitis has 

 been considered, but not proved. Various toxic agents 

 (poisons) will bring about a disturbance in the function of 

 the normal metabolic processes in the body and possibly 

 bring on the condition or predispose to it. (/) Absence of 

 sunlight, dark, damp and unsanitary cellars are no doubt 

 predisposing causes. Heredity has been mentioned also as 

 having some influence in the development of the disease. 

 It is quite evident that the exact etiological factor in the 

 production of rachitis has not yet been determined. 



Pathology.— The deformity occurring in rachitis is found 

 mainly in connection with the long bones. The diaphyses 

 of the bones are shortened, softened, become curved. The 

 epiphyses are thickened, more or less spongy, and much 

 enlarged. The bones are much softer than normal and have 

 the consistency of decalcified bone. They can be cut easily 

 with a knife. The periosteum is thickened, reddened and 

 when removed from the bones may include some of the bone 

 substance. In many cases the interior of the bones is soft 

 and the canal abnormally large. The short bones are found 

 spongy and easily separated. Marked deformity occurs in 

 the skull bones which are often separated. The patient in 

 general will show evidences of malnutrition. 



Symptoms.— During the early stages of the disease, before 

 deformity of the bones is present, there are gastric and 

 intestinal disturbances (catarrh), and evidences of mal- 

 nutrition. Weakness, loss of appetite, diarrhea and tendency 



