Compounded Enrofloxacin: Safe and Effective for Use in Mares

Researchers said a water-based enrofloxacin suspension could be useful for treating some bacterial endometritis cases.

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You’ve probably read warnings about the risks of administering compounded drugs (in which the preparation, strength, or flavor has been changed to meet a patient’s particular therapeutic requirement) to horses: lack of federal regulations, inconsistent quality, and so forth. But these medications do serve an important purpose.

For mares with endometritis, for instance, a compounded form of the antibiotic enrofloxacin might cause fewer side effects than the commercial product. Researchers from Washington State University (WSU) teamed up with veterinarians at Rood & Riddle Equine Hospital, in Lexington, Kentucky, to find out.

"Endometritis—an inflammation of the endometrium that lines the mare’s uterus—is a common cause of low pregnancy and foaling rates," explained presenting author Lisa Pearson, DVM, MS, Dipl. ACT, a theriogenologist at WSU’s College of Veterinary Medicine, during the 2014 American Association of Equine Practitioners Convention, held Dec. 6-10 in Salt Lake City, Utah.

Enrofloxacin is an effective treatment against almost all of the bacteria isolated from endometritis cases. Pearson and her colleagues observed in a previous study, however, that mares developed severe hemorrhagic inflammation and fibrosis (scarring) in their endometrium in response to intrauterine commercial enrofloxacin (Baytril-100) administration. She said the product’s high pH level can be caustic to the endometrium

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Alexandra Beckstett, 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. She was the managing editor of The Horse for nearly 14 years and is now editorial director of EquiManagement and My New Horse, sister publications of The Horse.

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