DISEASES FOLLOWING PARTURITION. 245 



constriction and thickening of the canal extend the whole length of 

 the teat, it is practically beyond remedy, as the gland is usually in- 

 volved 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 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 w^ithout 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 w^ay 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 dis- 

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

 form it is necessary only to dissexit 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 super- 

 fluous gland through its duct with a caustic solution, so as to destroy 

 its secreting powxr. In both cases it is desirable to wait until the 

 cow goes dry. 



