894 SPRAIN OF THE CORONARY JOTNT. 



Loss of the hoof also follows neglected corns, or pricks in shoeing; 

 the injury no1 beng detected owing to flic animal showing no signs 

 of lameness. But in the majority of cases, unnerved horses continue 

 serviceable for a year to two years or even longer, according to the 

 nature of the disease for which the operation was performed. In 

 some cases neurectomy may be performed twice, at an interval of 

 18 months to two years, and the subjects may work satisfactorily 

 for a further period of two years or longer, but very few horses remain 

 long useful after a third operation. Recurrence of lameness may 

 be due to compression of the central end of the resected nerve, to 

 re-establishment of sensation in the primary seat of disease, or to 

 some cause existing above the point of operation. The first arises 

 from growth of new connective tissue (" amputation fibroma," 

 or " neuroma ") around the stump of the nerve, and the lameness 

 can be removed by excision of the fibrous growth, or by resecting 

 the nerve above the enlargement. 



VI.— SPRAIN OF THE CORONARY JOINT. 



Whilst luxations of -the phalanges are rare, sprain is more common, 

 particularly in the coronet-joint. It occurs either from excessive 

 dorsal or volar flexion or forced lateral movement in the joint, caused 

 generally by slipping to the side, and consists in violent stretching, 

 sometimes in partial rupture of the ligaments. 



Such accidents are favoured by — 



(1) Defective formation of the joints. Small articular surfaces 

 offer less secure support, and are generally furnished with weak 

 ligaments. This is particularly true of joints which appear narrow 

 when seen from in front. 



(2) Faulty position of the limb. The most important of such 

 faults is turning the toes outward or inward. If the axes of the 

 joints are not perpendicularly under the centre of gravity, unequal 

 stress must be thrown on the ligaments every time weight falls on the 

 limb ; in addition, unequal weight being thrown on the inner and 

 outer portions of the joints, the gait becomes insecure. 



(3) Narrow hoofs and excessive lowering of the wall. Where one 

 side of the wall comes in contact with the ground sooner than the 

 other, the load is unevenly distributed, and the lateral ligaments 

 are apt to suffer. Horses which have worked for a long time under 

 such conditions generally show excessive lengthening of the ligaments, 

 best recognised in a position of volar flexion. The immediate causes of 

 sprain are slips, falls, or injuries sustained in rising. Such accidents 



