Passing from the stifle to the hock, we have here to notice in the first place the " point", which should be free from every form of swelling. Sometimes, as a result of injury, enlargement of this part is found to exist. The enlargement will vary in its character in different cases, and also in its relation to legal soundness. A capped hock, as it is termed, may consist of nothing more than a little fluid infiltrating the loose tissue beneath the skin, and causing no present or prospective interference with the horse's action or power to work, in which case its presence is not inconsistent with a state of soundness; but it would be otherwise if the swelling were inflamed and painful, and caused the animal inconvenience, or if it involved the synovial sac which intervenes between the tendon and the point of the bone, as the one plays over the other.

From the point of the hock downwards to the fetlock-joint the posterior border of the leg should descend in a straight line. It sometimes, however, happens that this rule is departed from even in the absence of disease.

When the head of the outer splint-bone is more than usually developed, as sometimes occurs, a bulging is formed behind the hock which gives the appearance of a curb, and has on many occasions been mistaken for one. The bulging caused by a true curb stretches across the back of the leg, while the projection formed by the bone is confined to the outer side, where the bone is situated. Moreover, when the fingers are passed over a curb, it is found to yield somewhat to pressure, whereas the bone is hard and resisting.

Curbs vary very considerably in size. Some are observable and distinguishable at once, but others are small and only just raise the line of the leg.

Although horses having curbs must be regarded as unsound, it must not be lost sight of that many animals so affected do life-long work without further mishap, and we should therefore say that, where the curb is small and unattended with lameness, the legs well formed, and the horse in hard condition, but little risk would attend the purchase of such an animal if the work required of him was not severe.

Many good horses, because of curb, have been rejected by intending purchasers in favour of an indifferent brute having some sort of title to be called "perfectly sound".

In front of the point of the hock and behind the leg-bone is the tendon of the deep flexor muscle, whose sheath sometimes becomes largely distended with synovia, forming a fluctuating tumour passing from one side of the hock to the other, and commonly termed thorough pin. Young horses are most frequently its subjects, and especially those of the heavy breeds while being got up for show. Although an unsoundness for the time being, it should not be forgotten that they frequently disperse altogether without showing any disposition to return.

A similar condition may also be found to exist in the true hock-joint, the capsule of which is made to bulge at the upper and inner part by synovial distension, causing what is termed a "bog spavin" (Vol. II, p. 290). Here again we have a state of unsoundness which, when occurring in young animals, frequently disperses and may not recur.

Having decided as to the presence or absence of bog spavin, the examiner then passes the hand over the inner face of the joint, taking note of any abnormal condition or swelling at the lower part, which is the seat of bone spavin (Vol. II, p. 217). As to whether such a disease exists or not is frequently a difficult and sometimes an impossible question to answer correctly, even by the most accomplished expert.

The conformation of the hock varies to a considerable extent in different animals of the same variety, and in many instances in the two hocks of the same animal, when the hocks are said to be "odd".

In some they present a relatively flattened surface, the natural bony prominences being slight, and the general outline of the joint is regular and refined, while others are conspicuous by their coarseness, in which the natural prominences of the bone are greatly exaggerated, and stand out from the surface in bold projections. Such hocks are known as "coarse hocks", but in numerous instances, where the coarseness has been specially marked over the seat of spavin, it has been mistaken for that disease. To distinguish between the normal and the abnormal condition in these cases needs not only a large experience of hocks at all periods of life, but a clear comprehension of the anatomy of the part.

Coarseness of the hocks is generally associated with the same condition in the other joints of the extremities, and these will sometimes help in a solution of the difficulty.

It remains, however, that bone spavin, as an objective symptom, is an abnormal growth of bone on the inner and inferior part of the joint, but with this there is usually associated more or less disease of a destructive nature going on between the bones, by which their articular surfaces become disorganized. It follows from this that the malady is attended with lameness, in which the hock-joint is but imperfectly flexed, the step is short, and the weight of the body quickly displaced from the affected limb. When this disease is suspected, some confirmation may be found in the fact that the affected animal leaves the stable with a halting gait after rest, which becomes much less pronounced or altogether disappears as he continues a journey.

The disease we have already referred to as existing between the bones of the hock may be present without any perceptible enlargement on the surface, but all the other symptoms described will be present. This condition is termed "occult spavin" from the fact that there is no visible enlargement to account for the lameness which, judged by the action, is due to hock mischief.

Whether the disease be occult or visible, spavin, it is hardly necessary to say, constitutes an unsoundness of the worst form.