Iowa State University Veterinarian Records, RS 22/6/0/9, University Archives, Special Collections Department, Iowa State University, http://www.add.lib.iastate.edu/spcl/arch/rgrp/22-6-0-9.html
Infertility in the mare results in a significant loss of dollars in the horse industry every year. It is defined as the absence of the ability to conceive. There are many causes of infertility that are recognized, including infectious, inflammatory, a faulty uterine immune system, trauma and scarring, hormonal, twinning, neoplasia, and congenital abnormalities.
Ebert, Mary A. and Riese, Richard L.
"Infertility in the Mare,"
Iowa State University Veterinarian: Vol. 48
, Article 4.
Available at: http://lib.dr.iastate.edu/iowastate_veterinarian/vol48/iss1/4