Scabby teats may be smeared with vaseline containing carbolic acid enough to give it an odor.
TEAT BLOCKED BY CONCRETION OF CASEIN.
Under unhealthy conditions of the gland or milk ducts clots of casein form which, pressed clear of most of their liquid and rolled into rounded masses, may block the passage. They can be moved up and down by manipulation of the teat, and if they can not be pressed out they may be extracted by using the spring teat dilator ([Pl. XXIV], fig. 3), being held surrounded by its three limbs. Before extraction is attempted an ounce of almond oil, boiled, should be injected into the teat.
TEAT BLOCKED BY CALCULUS.
When the calcareous matter of the milk has been precipitated in the form of a smooth, rounded stone, a rough, conglomerated concretion, or a fine, sandlike débris, it may cause obstruction and irritation. These bodies are felt to be much harder than those formed by casein, and the milk usually contains gritty particles. Extraction may be attempted, in the case of the finely divided gritty matter, by simple milking or with the spring dilator ([Pl. XXIV], fig. 3) in the case of the larger masses. Should this fail the teat may be laid open with the knife and sewed up again or closed with collodion, but such an operation is best deferred until the cow is dry.
TEAT BLOCKED BY A WARTY OR OTHER GROWTH INSIDE.
In this case the obstruction may be near the orifice of the teat or farther up, and the solid mass is not movable up and down with the same freedom as are concretions and calculi. The movement is limited by the elasticity of the inner membrane of the teat from which it grows, and is somewhat freer in certain cases because the growth has become loose and hangs by a narrow neck. In the case of the looser growths they may be snared by a fine, spring wire passed as a loop through a fine tube (like a teat tube open at each end) and introduced into the teat. When this can not be done, the only resort is to cut in and excise it while the cow is dry.
THICKENING OF THE MUCOUS MEMBRANE AND CLOSURE OF THE MILK DUCT.
As a result of inflammation extending from without inward, a gradual narrowing of the milk duct may occur from thickening and narrowing of its lining membrane. This may be limited to a small area near the lower end, or it may extend through the whole length of the teat. The stream of milk becomes finer and finer until it finally ceases altogether, and a firm cord is felt running through the teat. If the constriction is only at the outlet, the teat may be seized and distended by pressing the milk down into it from above, and an incision may be made with a sharp penknife in two directions at right angles to each other and directly in the original opening. The knife should be first cleansed in boiling water. The opening may be kept from closing by a dumb-bell shaped bougie of gutta-percha ([Pl. XXIV], fig. 5) or by the spring dilator. If the obstruction is more extended it may be perforated by Lüthi's perforating sound. ([Pl. XXIV], fig. 1A and 1B.) This is a steel wire with a ring at one end, and at the other is screwed on to the wire a conical cap with sharp cutting edges at the base, which scrapes away the thickened masses of cells as it is drawn back. This may be passed again and again to enlarge the passages sufficiently, and then the passage may be kept open by wearing a long, dumb-bell bougie, a thick piece of carbolized catgut, or a spring dilator. If the passage can not be sufficiently opened with the sound it may be incised by the hidden bistoury. ([Pl. XXIV], fig. 2.) This is a knife lying alongside a flattened protector with smooth, rounded edges, but which can be projected to any required distance by a lever on the handle. The incisions are made in four directions, as deep as may be necessary, and the walls then can be held apart by the spring dilator until they heal. In case the constriction and thickening of the canal extend the whole length of the teat, it is practically beyond remedy, as the gland is usually involved so as to render it useless.