994 Veterinary Obstetrics 



influence upon the process of milking. The teat walls ma}' be 

 very thick, leading to a small lumen of the'teat canal, accom- 

 panied by difiScult milking, but this condition cannot be regarded 

 as pathologic. In addition to these there may be transverse folds 

 of the mucous membrane projecting out into the milk cistern, 

 which may possibly be normal, and yet may offer some obstruc- 

 tion to the passage of the milk. 



Jensen records the occasional, occurrence of perpendicular par- 

 titions in the cistern of the teat, constituting essentially double 

 teats. There may be supernumerary cisterns, with small teat 

 canals opening near the base of the teat, so that they behave as 

 milk fistulae. Vennerholm states that there frequently occur, 

 in the cistern, small papilloma, which .interfere with the pas- 

 sage of the milk by partially filling the cistern. Such 

 papilloma may also become displaced and, dropping into the 

 teat canal, partially block it. The cause of these papilloma is 

 presumably the previous occurrence of trauma. 



The stricture or atresia may occur at any point in the teat, 

 from its apex to its base. Most of the lesions are found 

 at the base of the teat or in the teat canal at its apex, while 

 the capacious cistern remains comparatively free. 



The symptoms of stricture or atresia will depend primarily 

 upon the location of the lesion and its extent. If the stricture 

 or atresia occurs in the teat canal, the teat promptly and read- 

 ily becomes distended with milk, but it is exceedingly difficult 

 or impossible to press it out through the teat orifice. When the 

 milk is forced out, it c6nies^wa!y in a fine stream. 



This condition should not be confounded with those instances 

 in the cow where the teat canal is normally very narrow and the 

 sphincter muscle surrounding it is very powerful, rendering milk- 

 ing exceedingly difficult. In such cases, ordinarily, all four teats 

 of the cow are alike, and merely require extra pressure in order 

 to force the milk through the narrow canal. ' Such teats are 

 normal upon digital palpatiori, and in other respects. 



By palpation of teats affected with stricture or atresia, one can 

 usually recognize a hard, dense. Cord-like thickening along the 

 position of the teat canal, which indicates that the mucous mem- 

 brane and sub-mucous connective tissue are thickened and 

 indurated. 



In most cases in which the obstruction exists at the base of the 



