The Testing of Copper Intrauterine Devices to Mitigate Uterine Infections in Mares: A Preliminary Study

Abstract This preliminary study evaluated the effectiveness of a novel hormone- and drug-free copper intrauterine device POD (CuiUPOD) with one to three copper-coated magnetic units in controlling Streptococcus equi subsp. zooepidemicus in seven intrauterine-inoculated mares. Initially, one unit was inserted into each mare and animals were followed weekly with trans-rectal ultrasonography, blood progesterone assay, uterine swabs for cytology and microbial culture, uterine specimens for biopsy, and trans-abdominal detection of the CuiUPOD using a handheld magnetic detector or a cell phone compass. Infection persisted after a CuiUPOD with one magnetic unit was inserted, but subsided shortly after two additional magnetic units were added. By day 60, at device removal, and after a 30-day exposure to copper, none of the mares presented with clinical signs of infection. On a scale of I-III (I, IIA, IIB, III), with I representing a healthy uterus, endometrial biopsies at the time of CuiUPOD removal, showed improved biopsy scores in two of seven mares (29%; p < 0.05). The in vivo experiments, complemented by an in vitro experiment, demonstrated a time- (24-96 hours) and dose-dependent response to Cu: three CuiUPODs - OD readings = 0.538; two CuiUPODs - OD = 0.513; and one CuiUPOD - OD = 0.452. As the concentration of copper increased, so did the antimicrobial effect. These findings suggest a promising use for the one-time application of a CuiUPOD with two or three magnetic units to mitigate uterine infections in mares. Simple Summary Only a limited number of antimicrobials are effective against most resistant bacteria. Several studies have demonstrated the biocidal effect of copper on bacteria, fungi, and viruses. Copper-containing intrauterine devices provide a non-pharmacological solution to prevent and treat uterine infections in equids. This preliminary study provides evidence of the antimicrobial properties of copper both in vivo and in vitro and explores its possible application in mare reproductive practice. A 30-day intrauterine exposure to copper showed no clinical signs of infection with a common bacterium in horses - Streptococcus equi subsp. zooepidemicus - in intrauterine-inoculated mares. As the concentration of copper increased, so did the antimicrobial effect. Copper intrauterine devices show promise in mitigating uterine infections in mares.