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 [the structure formed after the follicle that releases the egg, or ovulates, and then produces progesterone] 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.
So how is this accomplished? There are a number of options, Threlfall explained.
Surgical Correction--If the problem is serious enough and structural, a veterinarian might need to correct it surgically, Threlfall said. If surgery is indicated, he said, it's advisable to carry out the procedure. Threlfall noted that surgery is the most "permanent" uterine therapy and is often used to correct perineal lacerations, urine pooling, cervical lacerations, and rectovaginal fistulas.
Sexual Rest--Threlfall said that some healthy mares are able to clear pathogens and inflammation from the uterus without medical treatment. Sometimes all a mare needs is sexual rest and multiple estrous cycles to clear her uterus, he added. This was one of the first treatments for subfertility but is generally not recommended today because of low success and reproductive time lost, he added.
Hormonal Preparations--Several hormonal preparations are available that could help improve uterine tone and decrease uterine size in sub- or infertile mares, Threlfall said. The most common hormones used for this purpose are oxytocin and prostaglandin, he said, stressing that each case should be treated as an individual and should receive tailored doses as prescribed by a veterinarian.
Intrauterine Antibiotics, Antiseptics, or Irritants--In cases of chronic uterine inflammation, Threlfall said, veterinarians sometimes use irritants or antiseptics to prompt the healing process. Placing certain irritants such as vinegar, iodine, bleach, or Nolvasan solution in the uterus could prompt an acute inflammatory change to "jumpstart" the healing process.
Other less commonly used irritants include white gasoline, kerosene, and a Nolvasan suspension; however, Threlfall did not recommend using these preparations. "Don't put anything in the uterus that you don't know is going to do more good than harm," he stressed. Veterinarians should dilute all irritants before placing them in the uterus, Threlfall said. This procedure should not be performed by anyone other than a qualified veterinarian, he added.
Veterinarians can also use intrauterine antibiotics, he said. It's best to culture each mare to determine which antibiotics will most effectively treat specific pathogens in the uterus. Threlfall recommended aiming for three to five days of antibiotic treatment, noting that additional infections can develop with prolonged antibiotic use. Avoid mixing antibiotics or irritants with antibiotics, however, as the results are unknown, Threlfall cautioned.
Uterine Flushes--A common and popular treatment option for uterine problems are uterine flushes, Threlfall said. He suggested using a warm solution when flushing the uterus, a technique that improves uterine tone and decrease uterine size.
In some cases the veterinarian identifies a fungal pathogen in the uterus, Threlfall said. For these cases he suggested three treatment modalities:
- Sexual rest (with no additional treatment);
- Uterine infusion with iodine; or
- Uterine infusion with the antifungal agent such as nystatin.
Threlfall stressed the importance of reevaluation once the veterinarian administers treatment. If the mare has improved, the veterinarian can offer recommendations as to the next course of action. If the mare hasn't improved, the practitioner can implement a new treatment option or suggest the next logical step.
Threlfall also noted that prevention is the best treatment and encouraged breeders to implement best breeding-management practices. He also advised managers to keep an eye open for abnormalities that might indicate an internal problem in broodmares, as early treatment often yields better results.
Disclaimer: Seek the advice of a qualified veterinarian before proceeding with any diagnosis, treatment, or therapy.