Abnormalities of the tubular genital organs. 
Abnormalities of the tubular reproductive tract are responsible for decreased fertility in the cow.  Typically, these are related to congenital defects such as segmental aplasia or to acquired conditions resulting from infections or trauma caused during breeding or parturition.  Infection of the tubular tract may result in vaginitis, cervicitis, metritis, endometritis, pyometra, or salpingitis.  Trauma to the tract may result in urovagina, pneumovagina, or prolapse of the vagina or uterus.  Retained placenta may result in metritis.  Potentially, all of these conditions, unless properly treated, may result in reduced fertility or, in the extreme, sterility.  Judicial and properly timed use of antibiotics and ecbolic agents should return the tract to proper function with little or no reduction in fertility.  Some conditions, such as prolapse, retained placenta, and pneumovagina, may call for manual or surgical intervention for successful resolution.