CHAPTER V. 



DISEASES OF THE MAMMARY GLANDS. 



In animals used for the purpose of providing milk, viz., cows, 

 goats, and milch ewes, diseases of the mammary glands are of daily 

 occurrence, but are rare in those in which the mammary function is 

 limited to the nourishment of the young, such as the mare, female ass, 

 sow, etc. 



In order clearly to understand the development of these diseases, 

 it is necessary to bear in mind the anatomical construction of the 

 organs, for which purpose we may take as a type the mammary gland of 

 the cow, which is the most complicated. 



The udder of the cow is of hemispherical shape. It is situated in 

 the inguinal region, and is composed of two parts, the right and left, 

 which are absolutely independent and can easily be isolated from each 

 other along the median plane throughout their extent. The mass of 

 parenchyma is enveloped in a fibrous envelope, which is covered with a 

 very loose layer of subcutaneous connective tissue. Each half is sub- 

 divided into two quarters, an anterior and a posterior quarter. Each 

 quarter again represents a distinct gland, althoiigh anatomical separa- 

 tion between the anterior and the corresponding posterior quarter would 

 be almost impossible, the separating fibro-connective partition being 

 common to both glands. 



In very good milkers it sometimes happens that two small supple- 

 mentary glands may be found behind the posterior quarters, bringing 

 up the total number to six. 



Parenchyma. — Each of these glands is i^rovided with a teat contain- 

 ing a large sinus. Anatomically the mamma consists of glandular tissue 

 arranged like a bunch of grapes, in which the active tissues of the acini 

 deliver their secretion into little excretory canals, which unite, formiug a 

 large collecting plexus. The collecting canals, or galactophorous canals, 

 open into the galactoi^horous sinus, which occupies the entire depth of 

 the teat and communicates with the exterior by a small pore provided 

 with a sphincter. The interacinous connective tissue of the udder and 

 the subcutaneous tissue of the teat, which envelops the galactophorous 



