48 Diseases of the Genital Organs 



ing, or standing to be mounted by, other animals of its 

 species. The ewe ordinarily shows little or no evidence of 

 estrum except in the presence of the male. In certain 

 pathologic cases (nymphomania) the cow especially does 

 not confine her expressions of sexual desire to her own 

 kind, but may attempt to mount other species of animals. 



In all animals there is a tendency during estrum for the 

 female to wander from home. This is most noticeable in 

 the bitch and the cat, which, if not securely confined, disap- 

 pear, tending to wander long distances and to remain away 

 during a large part or all of the estrual period. The sexual 

 wanderings of domestic animals constitute an interesting 

 chapter in the dissemination of infectious diseases. 





Fig. 23 — Section of ovary of cow showing a follicle of 

 2 mm., with ovum. 



The female exhibits sexual desire only for a compara- 

 tively brief time, during the existence of a ripe ovisac or 

 ovisacs in the ovary. The duration of the estrual period 

 varies widely, according to species. It is shortest in the 

 cow, ranging ordinarily between eighteen and twenty-four 

 hours, or a trifle longer. The mare is usually in estrum for 

 several days. The bitch is in estrum for ten to fifteen days. 

 In healthy females, the estrual cycle is quite uniform. In 

 the cow it is twenty to twenty-two days, usually twenty-one ; 

 in the mare 3 to 4 weeks ; in the bitch ordinarily every six 

 months. The frequency, intensity, and duration of estrum 

 are profoundly modified by the state of nutrition, diseases 

 of the genital organs, and by serious systemic diseases. 



