MENSTRUATION 



In all domestic mammals, there occurs in those females of 

 breeding age, at the time of estrum, an excitation of the genital 

 tract with increased activity of the mucous glands, especially of 

 the vagina and vulva, which leads to a more or less pronounced 

 discharge of mucus. 



In addition to this increased production of mucus, there occurs 

 in some animals, during or immediately subsequent to estrum, 

 an evident discharge of blood from the vulva, which, mixed with 

 mucus and epithelial debris, is known as the menstrual fluid ; 

 the process, as menstruation. The phenomenon is not so con- 

 spicuous in any of our domestic animals as is ordinarily observed 

 in woman, and, for the most part, usually passes unobserved, 

 if present. It is quite commonly noted in the cow and bitch. It 

 has been recorded in the mare by Fleming (Veterinary Obstet- 

 rics) and Kaiser (Magazine, 1859). Many regard estrum and 

 menstruation as synonymous. While they are intimately re- 

 lated, we prefer to regard them as two separate phenomena, as 

 observed among domestic animals. 



While estrum is common to all mammalian animals of breed- 

 ing age at the breeding period, menstruation, or a muco-sanguin- 

 ous vaginal discharge, is not observable in most species at all, 

 and, in the cow, where it is most conspicuous, It ordinarily does 

 not occur during, but subsequent to, her very brief estrual period. 

 In the bitch, the relation is -not so well determined, the e-strual 

 and menstrual phenomena being of greater duration and over- 

 lapping or occurring simultaneously. In the cow, there is very 

 frequently noted at or near the close of the period of sexual de- 

 sire a well marked discharge of blood from the vulva. The 

 amount varies greatly, usually being limited to a sufficient quan- 

 tity to plainly stain the tail and surrrounding parts so that they 

 are distinctly bloody, but sometimes there is a large amount of 

 blood of a bright red color, mixed with mucus, seen hanging from 

 the inferior vulvar commissure. In a few cases we have observed 

 quite a voluminous discharge of blood, amounting at times to 

 several ounces and accompanied by some constitutional disturb- 

 ance, consisting chiefly of decreased appetite and a loss of milk. 

 This sanious discharge in the cow continues usually for only a 

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