242 DISEASES OF CATTLE. 



enlarge the passage, and then the passage may be kept open by wear- 

 ing 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. (PI. 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 

 and as deep as may be necessary, and the walls can then 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. 



CLOSURE OF THE MILK DUCT BY A MEMBRANE. 



In this form the duct of the teat is closed by the constriction of its 

 lining membrane at one point, usually without thickening. The clos- 

 ure 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 a 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 (PI. 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 may be then held apart by wearing 

 the spring dilator until healing has been completed. 



In all cases of operations on the teats the instruments must be thor- 

 oughly 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 dis- 

 tinct milk duct and an independent portion of the gland. In the first 

 form it is only necessary to dissect away the skin leading into the open- 

 ing 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 off the milk 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 inci- 

 sion 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. 



