Tendon strain

Tendons are fibrous structures that connect muscle to bone. Their function is to transfer the pull from the muscle in order to move the bone. As the horse does not have any muscles lower down the leg than the knee or the hock, the major tendons associated with walking, trotting, galloping and so on are relatively long and also susceptible to injury. Ligaments have basically the same microscopic structure as tendons, but their function is to join two bones together.

Cause
Strain occurs when the natural ability of the tendon to stretch and rebound to normal is exceeded.
The racehorse and especially the chaser is most at risk because of the tremendous strain that these tendons have to withstand as the horse lands at speed over the large fences. Also, both the event horse as he tackles the cross-country phase, and the endurance horse, although in this discipline it is not force that does the damage, but fatigue -after a long mile-race the tendons can be so tired that even relatively minor strains can cause extensive damage.

Symptoms
There is a varying degree of lameness, depending upon the amount of damage sustained to the tendon. In severe cases the foot is held raised, with maybe a little weight taken on the toe. When tendons are damaged there are classic symptoms of inflammation: the area is hot, painful and swollen with inflammatory fluid separating the previously tightly packed tendon fibres, increasing the cross-sectional area of the tendon but also drastically weakening it mechanically. Individual fibres are damaged and torn. The most common site of tendon damage is down the back of the cannon bone, especially of the front legs.
The swelling can be so marked that without an ultrasound scan it is difficult to assess the extent of the damage. Ultrasound images are essential if a meaningful prognosis is to be made.

Treatment
-The first treatment is cold therapy applied to the area to reduce the amount of blood and fluid pouring into and between the damaged fibrils. The most practical method is some form of ice pack, secured by a firm bandage.
-Anti-inflammatory agents injected into the damaged area, or given intravenously will help and will reduce the pain
Recovery from a sprained tendon is slow and it will be six to nine months before the horse is back in work again. The exercise will increase gradually during this time. It is difficult to tell when a sprained tendon has recovered enough to withstand fast work. Ultrasound evidence of healing is the best indication.