PHYSIOLOGICAL ANOMALIES. 567 



The retro-mammary lymphatic glands are two in number, and are 

 situated very high and towards the back, above the posterior quarters 

 and close to the perineum, outside the fibrous envelope of the gland. 

 They are sheltered in a recess excavated within the depths of the gland 

 itself. The main collecting lymphatics from the anterior and posterior 

 quarters enter it separately. 



The lateral efferent vessels are divided into two groups, one 

 of which ascends vertically in the ■ perineal region, towards the 

 lymphatic glands round the anus : the other passes through the in- 

 guinal canal towards the sub-lumbar region, together with the blood- 

 vessels. 



The mammary nerves are two in number. The anterior has a 

 downward course outside the fibrous envelope and supplies the teat ; 

 the posterior nerve is similarly distributed. In other domestic female 

 animals which have only two mammae the general arrangement is 

 precisely the same. 



PHYSIOLOGICAL ANOMALIES. 



Imperforate condition of the Teat. — It sometimes happens that 

 although the udder is otherwise well formed, the teats, or more 

 frequently a single teat, proves to be imperforate. Between the galac- 

 tophorous sinus and the exterior, opposite the sphincter, a little 

 membrane may be found which closes the teat and entirely prevents 

 the contents of the udder from escaping. Its existence is only dis- 

 covered when the animal first calves and lactation commences. Not a 

 drop of milk can be withdrawn, although the udder is swollen. Local 

 examination readily reveals the defect. 



Treatment is very simple and effective, the membrane being per- 

 forated with the end of a milk catheter. 



Contraction of the Sphincter {Atresia of the Extremity of the Teat), 

 —Under other circumstances the teat may present a distinct per- 

 foration, and yet milking may be impossible, or at all events may be 

 extremely difficult. This is sometimes due to contraction of the sphincter, 

 or possibly to atresia of the orifice. 



The diagnosis of this condition is easy, but the outlook is not 

 promising. 



Treatment is rather difficult. Some operators recommend dividing 

 the terminal sphincter with a small, specially-formed bistouri cache, 

 provided with two cutting points. The operation has very satisfactory 

 immediate results, but after the little wounds so produced have healed, 

 cicatricial contraction takes place around the orifice. 



Forcible dilatation is far preferable. It is carried out in the same 

 way as in human medicine, where the sphincter ani or the orifice of 



