TYPES AND MARKET CLASSES OF LIVE STOCK 489 



shrunken, retracted in the orbit, and the lens develops a cataract. 

 After having destroyed one eye, the disease frequently affects 

 the other, and the history of the first is repeated. 



Poll evil. Poll evil is a fistula upon the poll of the head, 

 and in no sense differs from fistulous withers except in location. 

 It is caused by blows, bruises, and chafing by the halter or bridle. 



Ringbone. This is a bony growth at the coronet or on the 

 pastern, in either the front or hind legs. It is called "ring- 

 bone" because it often grows around the coronet so as to form \ 

 a ring, although in a large number of cases the growth takes \ 

 the form of a lump on the pastern, rather than that of a ring 

 at the hoof-head. This disease may result from severe work 

 in early life, from bruises, blows, or sprains, or from improper 

 shoeing. Ringbone often follows an abscess of the coronet, or 

 a deep-punctured wound. It is also classed as an hereditary 

 unsoundness, horses with short, upright pasterns being pre- 



A B C 



Fig. 167. Ringbone and Cocked Ankle. 



A, Sound; B, ringbone; C, cocked ankle. 



disposed. Ringbones often cause lameness which may disap- 

 pear with exercise, returning again when the animal is cooled. 

 They may or may not stiffen the joint. The size of the ring- 

 bone is not so important as its position. If it is located so as 

 to interfere with the movement of the tendons behind or in 

 front of the foot, it is a very serious trouble. Prevention of 

 ringbones consists in keeping foals well nourished, and keeping 

 the hoofs in balance. Curative measures consist of so shoe- 

 ing as to straighten the axis of the foot and pastern as viewed 

 from the side; blistering, followed by a few weeks of rest; and 

 point firing in two or three lines over the ringbone. When 

 these measures do not relieve lameness, the only recourse is 

 nerving. 



Roaring or thick wind. Horses that make a loud, unnat- 

 ural noise in breathing are said to have thick wind, or to be 

 roarers, excepting those which manifest this trouble because 



