Conformation plays an important part in disordering the movements of the limbs and inducing these injuries.
Large, spreading feet, long, sloping pasterns, with inward or outward inclination of the toes, also conduce to it. In the latter case there is always a tendency on the part of the fetlock-joints to approach each other, and the more pronounced this is the greater is the risk of striking.
Young horses fresh from the pastures, which have not yet learnt the use and control of their legs when under saddle or between shafts, are most commonly addicted to brushing and cutting, and especially when tired or out of condition.
Defective shoeing, especially when coupled with faulty conformation, also conduces to this mishap. A shoe fitted too full, i.e. allowed to project beyond the crust on the inner side, is a frequent cause of it in young horses and in others when tired.
This discrepancy in favour of the front legs may, as Goubaux and Barrier affirm, be " owing to the fact that the separation between the hindfeet is generally less marked than that between the fore-feet"; but we are of opinion that this is not the only cause of the difference. The hind limbs being more especially engaged in propulsion, are more likely to have their line of action disturbed in acting upon the ground than the fore ones, which are more essentially supports, and it is not unlikely that the existence of calkins on the hind feet tends still further to misdirect the movements of the limbs.
Horses whose legs are long and set close together on a narrow trunk are frequently the subjects of brushing and cutting, as are also others whose feet are brought close to each other by the inward tendency of their limbs.
Cutting may also result from the accidental displacement of a shoe, or when the clinches are badly laid down.
However well balanced a horse's movements may be, he is often induced to cut when travelling over slippery roads.
The more serious effects of brushing and cutting are: - (l) Injury to the plantar nerve as it passes over the fetlock-joint; (2) bruises to the sesamoid bones, which may provoke an ossific growth ; (3) destructive cellulitis, resulting from the introduction of septic matter into the wounded skin.
Any attempt to mitigate or overcome this defect must be based upon a consideration of the cause out of which it arises. Where defective conformation is the cause, some attempt must be made to alter the direction of movement by the employment of a specially-formed shoe; what particular shape it should take is a question which has often to be decided by experiment. Before anything is done in this connection, the feet should in all cases be carefully examined without the shoes. It will then be seen whether there is any difference in the height of the inner as compared with the outer quarter of the wall, and whether the foot is taking a regular bearing all round.
Any disparity in the first point should be rectified, and the crust made level from heel to toe and from side to side. Where these conditions have been provided, a shoe should be tried whose inner branch is somewhat straight, and fitted well under the edge of the hoof (fig. 405). If this has not the desired effect, the edge of the crust of the inner quarter must be rasped down, the inner branch of the shoe made narrow, deep, rounded off at the edge, and fitted well under the crust.
The blow is usually inflicted by the inside toe, but may also be caused by the heel, especially in those cases where the toes are turned out. It may likewise be delivered by the middle of the crust, when the clinches, if not properly laid down, occasion nasty wounds in the skin.
Fig. 405. - Shoe to remedy "cutting"'.
It is very difficult, and sometimes impossible, to prevent this faulty action. Horses with long pasterns, whose toes turn out, are perhaps the least amenable to treatment. In these cases the injury may be inflicted by the inner part of the toe or by the heel, against both of which some provision should be made. A shoe with the inner branch straight, set well under at the heel, and well rounded off at the inside toe, is most likely to minimize the trouble if it does not altogether remove it.
Where this fails, a three-quarter shoe (fig. 408) with the toe similarly dealt with may be tried.
In old horses work should be apportioned to their powers, and young ones should be carefully conditioned and trained in the various evolutions they will be required to perform before being sent to active work. The weak must be strengthened by good living, and the sick withdrawn from work.