CURVATURE OF THE SPINE. 729 



also suffer from curvature of the spine in consequence of being trodden 

 on by other occupants of the sty. Piitz describes kypho-skoliosis 

 in an eighteen months' foal. The dorsal vertebrae were bent towards 

 the right, the lumbar vertebrae towards the left, and the back was 

 depressed in places. The condition described by Preusse (kypho- 

 skoliosis) in a foal appears to have been congenital. Vives noticed 

 a horse in which the lumbar vertebrae were bent downwards almost 

 at a right angle, and the thorax and abdomen were so depressed 

 that the latter almost touched the ground. A tree had fallen on 

 the animal's back, causing symptoms of vertebral fracture. After 

 some time recovery took place, but the vertebral column remained 

 bent. 



The causes of spinal curvature cannot always be identified, but 

 those usually accepted are congenital deformities, conditions resulting 

 from spinal fractures and luxations, rickets, osteomalacia, tuber- 

 culosis, and local diseases of the spine. 



The first are of the greatest interest, and are typified in the horse 

 by lordosis. Although little amenable to treatment, this condition 

 has a special interest from the prophylactic point of view. 



Lordosis develops during the first years of life, though occasionally 

 it appears later. The predisposing cause is weakness due to 

 abnormal length of the back. The extrinsic causes include all 

 influences leading to continuous or excessive strain on the spinal 

 column. Amongst these are the weight of the rider, distension of 

 the colon by bulky food, or enlargement of the uterus consequent 

 on pregnancy ; old mares which have bred regularly frequently 

 show lordosis. The collective result is to bend the spinal column 

 downwards. The inferior surface of the spine becomes extended, 

 the superior surface curved or compressed. In young animals the 

 lower portions of the vertebrae grow, while in the upper part growth 

 is checked by the increased pressure, and therefore, in time, the 

 spine tends more and more to assume that particular form. This 

 explains why in man work leads to kyphosis, in animals to lordosis. 

 Special disease processes, like rickets, may favour the development 

 of such deformities, but at present are little understood in animals. 



A second factor in the production of spinal curvature is local 

 disease of the vertebrae. The greatest number of cases have been 

 seen in oxen as a result of tuberculosis. Morot described twenty. 

 Hess in a steer saw kyphosis in consequence of tuberculous disease 

 between the second and third lumbar vertebrae. 



A twenty-five year old horse which had suffered for many years, and 

 in increasing degree, from hollow-back was found on post-mortem to have 



