In this form the duct of the teat is closed by the constriction of its lining membrane at one point, usually without thickening. The closure usually takes place while the cow is dry; otherwise its progress is gradual, and for a time the milk may still be pressed through slowly. In such case, if left at rest, the lower part of the teat fills up and the milk flows in a full stream at the first pressure, but after this it will not fill up again without sufficient time for it to filter through. This is to be cut open by the hidden bistoury ([Pl. XXIV], fig. 2), which may be first passed through the opening of the membrane, if such exists. If not it may be bored through, or it may be pressed up against the membrane at one side of the teat and opened toward the center, so as to cut its way through. Incisions should be made in at least two opposite directions, and the edges then may be held apart by wearing the spring dilator until healing has been completed.
In all cases of operations on the teats the instruments must be thoroughly disinfected with hot water, or by dipping in carbolic acid and then in water that has been boiled.
OPENING IN THE SIDE OF THE TEAT (MILK FISTULA).
This may occur from wounds penetrating the milk duct and failing to close, or it may be congenital, and then very often it leads to a distinct milk duct and an independent portion of the gland. In the first form it is necessary only to dissect away the skin leading into the opening for some distance down, to close the orifice with stitches, and to cover the whole with collodion. A teat tube or spring dilator may be worn to drain the milk off and prevent distention and reopening of the orifice. In case of an independent milk duct and gland one of two courses may be selected—to open the one duct into the other by incision and then close the offending opening, or to inject the superfluous gland through its duct with a caustic solution, so as to destroy its secreting power. In both cases it is desirable to wait until the cow goes dry.
DISEASES FOLLOWING PARTURITION.
DESCRIPTION OF PLATES.
Plates XXII, XXIII. Supports for prolapsed uterus. These illustrations show various appliances used in prolapse or inversion of the uterus. The uterus should first be returned to its proper situation and then some apparatus applied to prevent a recurrence of the inversion or protrusion.
Plate XXII: