When a rounded swelling occurs on the point of the elbow, the part is said to be "capped". Sometimes the enlargement is solid throughout, at others it consists of a sac containing a straw-coloured or bloodstained fluid.
Capped elbow (fig. 384) is the result of injury inflicted by the inner heel of the shoe, either in the act of lying down or while being down, or as a result of slipping while attempting to rise. In these cases the foot has been allowed to grow too long, or the heel of the shoe is unduly extended backwards so as to strike or irritate the elbow.
The swelling may appear in a few hours, or it may be of slow growth. If the injury is severe the tumour develops rapidly, and is besides hot and tender and mostly fluctuating to the touch, like a cavity filled with fluid. If, on the other hand, the elbow suffers only slight but repeated irritation by contact with the shoe, the growth is slow to develop. At first it is somewhat soft, but as it increases in size it becomes hard and solid, and exhibits but little pain or tenderness unless, as frequently happens, it is contused, when it may inflame and develop an abscess. In some instances these excrescences are allowed to reach a considerable size amounting to several pounds in weight. Capped elbow seldom causes lameness, but it is very unsightly.
Fig. 384. - Capped Elbow.
Where the injury is but slight, a dose of physic and repeated fomentation of the part will be all that is needed to disperse the swelling; but where it is severe and the enlargement considerable, it will most likely require to be laid freely open and the contained fluid evacuated. This should be followed by the injection of a small quantity of tincture of iodine into the sac, and the repeated daily application of weak carbolic solution and due regard to cleanliness. If the tumour is hard and callous, it should undergo a course of blistering or be dissected out; or if hanging by a narrow neck, it must be cut off, with due precautions against haemorrhage or bleeding. Horses which habitually injure the elbow should wear an elbow-pad (fig. 385) round the pastern, or a bandage may be wound round the foot when they are in the stable and at liberty to lie down.