Managing a subfertile mare is a challenging and frustrating problem for breeders, especially when the exact problem remains unknown. But rest assured–researchers are working to improve equine fertility and develop new uterine therapy options. At the 2012 Western Veterinary Conference, held Feb. 19-23 in Las Vegas, Nev., one veterinarian reviewed current uterine therapy options.

Before turning to uterine therapies for sub- or infertile mares, it’s important to ensure the mare is not already pregnant, said Walter Threlfall, DVM, MS, PhD, Dipl. ACT, a consulting theriogenologist (reproductive specialist) in Powell, Ohio, and professor emeritus in the Department of Veterinary Clinical Sciences at The Ohio State University’s College of Veterinary Medicine. While this explanation for sub- or infertility isn’t common, it’s certainly feasible, and a fetus could be injured or terminated by many reproductive therapies, he noted.

A number of factors could contribute to subfertility, Threlfall said; however, some of the most common involve the uterus:

• Endometritis (a failure of the uterus to clear foreign contaminants, such as bacteria or spermatozoa, resulting in inflammation of the inner lining of the uterus);
• Metritis (an infection and/or inflammation in the uterine lining and deeper layers of the uterus);
• Pyometra (infection of the uterus which starts with the presence of a corpus luteum on the ovary and pus buildup in the uterus);
• Perimetritis (a localized infection and/or inflammation of the tissues on the outer surface of the uterus); and
• Parametritis (infection and/or inflammation of the tissue adjacent to the uterus).

Once a veterinarian has diagnosed a condition, treatment goals include eliminating pathogenic organisms if present, eliminating uterine inflammation, reducing size of the uterus if enlarged, and eliminating uterine fluid if present, Threlfall said