CHAPTER II.. Circulatory Apparatus.

CIRCULATORY APPARATUS.

BLEEDING.

Bovine animals are usually bled from the superficial jugular, or the mammary vein.

=Bleeding from the Jugular.=—The animal having been suitably fixed, the jugular is raised by means of a cord drawn tightly round the base of the neck, and the vessel is opened with a fleam about the middle of the neck.

The skin of the ox being thick, a long-bladed instrument is necessary. When the bleeding ceases, the cord is removed: some practitioners take no precautions as regards the wound; it is better to insert a pin suture.

Bleeding from the jugular may also be performed with the trocar, particularly in animals with fine, thin skin.

=Bleeding from the Mammary Vein.=—The mammary vein may be opened with the fleam, the straight bistoury, or the lancet. The head is firmly fixed and the hind limbs controlled by a rope passed in a figure of eight above the hocks.

In bleeding on the left the operator places himself at an angle to the animal’s side, opposite the hypochondriac region, with his back towards the animal’s head, and holds the fleam in his right hand. To operate on the right-hand side the fleam is held in the left hand.

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.

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.

BLEEDING IN THE PIG.

Breeders sometimes bleed by slitting one of the animal’s ears or cutting the tail. It is preferable to bleed with a lancet from the marginal veins of the ear, the external saphenous vein a little above the hock, or the subcutaneous vein of the forearm.

SETONS, ROWELS, PLUGS, OR ISSUES.

Although the application of setons is still practised in horses, that of “issues” has largely been given up in bovine animals, although some practitioners still regard issues as of considerable value and as producing effects similar to, or better than, those of sinapisms.

They are usually inserted in the region of the dewlap; the materials employed comprise black and white hellebore, veratrine and stems of clematis.

Two methods are practised.

In the first, a transverse fold is raised in the skin of the dewlap, which is divided with a stroke of the bistoury, leaving a little aperture in the skin. By introducing the rounded ends of a pair of curved scissors the subcutaneous connective tissue is broken down, leaving a little space beneath the skin, into which the plug is introduced. Swelling takes places very rapidly—in twenty-four to forty-eight hours it is very considerable—and if the substance employed is violent in its action, like hellebore, it must be withdrawn, as otherwise considerable sloughing takes place. To facilitate this object a thread or piece of string is usually attached to the plug before it is inserted.

In the second method, the irritant material is attached to, or smeared on, a strip of broad linen tape which is passed in precisely the same manner as in the horse (see Dollar’s “Operative Technique,” pp. 107–111).