DISEASES FOLLOWING PARTURITION. 249 



XXIV, fig. 5) or by the spring dilator. If the obstruction is more 

 extended it may be perforated by Liithi's perforating sound. (PI. 

 XXIV, fig. 1(2 and lb.) This is a steel wire with a ring at one end, 

 and at the other is screwed onto 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 

 sufficiently enlarge the passages, 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 liidden 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 re- 

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

 volved so as to render it useless. 



CLOSIRE or 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 diy ; 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 pait 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 Avater 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 



