This method of bleeding always causes thrombus formation, on account of the low position of the opening in the vein. The animal’s bed should be kept very clean, in order to prevent any local infection which might cause hæmorrhagic or suppurative phlebitis. The lancet or bistoury can only be used in animals with very fine skin.
In bovine animals small quantities of blood are sometimes taken from the facial vein or the veins of the ear or tail.
BLEEDING IN SHEEP.
On account of the quantity of fatty tissue and wool covering the jugular furrow in the sheep, bleeding is scarcely practicable at that point. The operation is usually performed on the angular vein of the eye, the external saphenous vein, or the subcutaneous vein of the forearm.
In operating on the facial vein the animal’s head is firmly held, the operator compresses with the fingers of his left hand the facial vein at the point where it passes into the maxillary fissure, and with a lancet opens the angular vein of the eye or one of the other branches of origin which project prominently beneath the skin. Bleeding ceases as soon as the pressure is relaxed.
In the case of the external saphenous vein, the vein is raised by compressing the middle region of the limb and the vessel is opened with a lancet, a little above and towards the outside of the hock.
Fig. 294.—Angular vein of the eye and facial vein.
The subcutaneous vein of the forearm can be raised by compressing the fore limb below the elbow. The vein is visible throughout the length of the inner surface of the radius, and can easily be opened with a lancet.
It is also possible to withdraw small quantities of blood by opening the marginal veins of the ear.