566 Veterinary Medicine. 



Lesions aiid Pathology . Apart from the bones there does not 

 seem to be an absohite constancy in the lesions. There is usually, 

 however, a period of ill-health and fault}^ nutrition before the 

 lesions in the bones can be recognized. Tlius, there may be 

 gastric or intestinal congestion, or catarrh, indigestions, constipa- 

 tion alternating with diarrhoea, enlargement of the liver, spleen 

 and kidney with hyperaemia, and according to V. Jaksch, a 

 diminution of the salts of the blood. Beneke found that the 

 arteries are dilated throughout the entire body, but the heart does 

 not always participate in this distension. Tlie arterial dilatation 

 is very marked in the pulmonary artery, 5^et the lungs are rela- 

 tively small. In the bones there is a well marked hypersemia, 

 most prominent beneath the periosteum, in the cancellated tissue, 

 the line of junction of the epiphysis and diaphysis, and near tlie 

 articulating surface. The contents of the cancelli are of a deep 

 red, and the color shines through the articular cartilage giving it 

 a bluish tinge. The shaft of the l)one does not escape, but like 

 the epiphysis and epiphyseal cartilage may be soft and yielding to 

 pressure, and cut readily with the knife. 



At both points the process of growth is increased and its area 

 extended, but it is not completed by the full deposition of earthy 

 salts, and the softening is not confined to the new tissues, but ex- 

 tends into the subjacent bone as well. 



The chemical composition of the bone is profoundly altered, the 

 organic basis, at times amounting to 65 per cent., as compared to 

 33.30 per cent in the normal bone. The softened bone, yielding 

 under the weight of the body, bends out of shape at the epiphy- 

 seal cartilage, or even elsewhere, giving, rise to bow legs, devia- 

 tion of the joints inward, or other distortion. The periosteum is 

 red, thickened, the seat of exudate and easily torn from the 

 bone. 



The bones are often thickened by new deposit under the perios- 

 teum and especially at the junction with the epiphyses. Old 

 cases of distortion, the result of rickets, do not necessarily show 

 a deficiency of earthy salts, as these are restored in case of repair 

 and they may even be found in excess of the normal, increasing 

 the hardness of the bone. 



Causes. This disease does not seem to have been recognized in 

 Great Britain until the beginning of the 17th century, the period of 



