Laser Safe for Uterine Cyst Removal, Future Foaling Rates

Laser Safe for Uterine Cyst Removal, Future Foaling Rates

Foaling rates one and two years after successful cyst removal via laser photoablation were 74% and 65%, respectively.

Photo: Anne M. Eberhardt/The Horse

Uterine cysts are one of many conditions tied to mare infertility; whether it’s a lack of real estate on the uterine wall or an interruption of vital pregnancy establishment processes, it simply seems these tiny growths and pregnancies cannot coexist in some mares. Veterinarians can remove cysts to try to improve a mare’s ability to carry a foal to term, but they hadn’t sized up the efficacy of the most current technique until recently.

Because practitioners have had some success using a method called laser photoablation, Nicole Scherrer, DVM, of the University of Pennsylvania’s New Bolton Center, in Kennett Square, studied its efficacy in a group of broodmares treated at Rood & Riddle Equine Hospital, in Lexington, Kentucky, and presented her results at the 2015 American Association of Equine Practitioners Convention, held Dec. 5-9 in Las Vegas.

These cysts are common and not always problematic: 22.4% of the producing broodmare population have them; however, 55% of subfertile mares have them, said Scherrer.

Veterinarians typically see a significant increase in cyst numbers as mares age. Only 4% of broodmares under age 7 presenting to a clinic have cysts, 29% of broodmares ages 7 to 14 have them, and 73% of broodmares over age 14 have them.

But back to that 55%. How can growths this small have such a detrimental effect on fertility? Scherrer said researchers have two theories: They cause the mare’s body to not recognize pregnancy, and/or they cause inadequate placental exchange of blood and nutrients necessary for fetal growth.

There are two types of cysts at hand. Small glandular cysts are solid tissue and only a couple of millimeters in size, whereas lymphatic cysts are often fluid-filled and can grow up to several centimeters; these are most likely the ones affecting fertility, said Scherrer. Researchers have shown that mares with more than five cysts or with cysts larger than 1 cm have lower pregnancy rates, she added.

Historically, treatment has included manual removal, aspiration, and uterine lavage. Manual removal, while inexpensive, is only effective on large cysts, and lavage has poor efficacy. Aspiration of the cystic fluid leaves the capsule behind, which is likely to fill back up again in the future. Veterinarians have also performed laser photoablation (basically, cutting the cyst away with a laser) with standing sedation, which allows the veterinarian to visualize and accurately remove the cyst, but researchers had not evaluated its effect on future foaling rates.

In her retrospective study, Scherrer looked at 42 Thoroughbred mares (45 total cysts) that had undergone uterine cyst laser ablation at Rood & Riddle from 1992 to 2011. She found that one and two years after the procedure, their foaling rates were 74% and 65%, respectively.

Mares younger than 17 were more likely to produce a foal than older mares (96% foaling rate vs. 58%), and cyst number and location had no significant effect. Short-term complications included mild hemorrhage, and long-term complications included recurrence in seven cases.

Overall, said Scherrer, this study “shows that diode laser photoablation is a safe, effective procedure for cyst removal and future foaling. The foaling rate the year after removal of the cysts was similar to that reported for normal Thoroughbred mares in Central Kentucky.”

She added that it’s important to keep in mind that the group of study mares had an average age of 17 years, which is significantly older than the average broodmare population.

Also, the laser requires special training and a significant financial investment, so large, multispecialty clinics are more likely to offer this procedure than smaller ones, she said.

About the Author

Alexandra Beckstett, The Horse Managing Editor

Alexandra Beckstett, Managing Editor of The Horse and a native of Houston, Texas, is a lifelong horse owner who has shown successfully on the national hunter/jumper circuit and dabbled in hunter breeding. After graduating from Duke University, she joined Blood-Horse Publications as Assistant Editor of its book division, Eclipse Press, before joining The Horse.

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