Any opportunity to avoid using antibiotics for treatment is ideal for limiting the potential for microbial resistance. Endometritis is often addressed using anti-microbial agents, but one study in India looked at the use of non-drug options for treatment [Mahal, J.S.; Honparkhe, M.; et al. Efficacy of Intrauterine Hydrogen Peroxide and Povidone Iodine Administration to Treat Endometritic Mares. International Journal of Current Microbiology and Applied Sciences 2020, 9 (03): 2427-2431; you can download the open access article here].
Endometritis in 35 mares was confirmed with transrectal ultrasound and uterine cytology. The mares had cloudy, turbid vaginal mucous discharge during estrus and despite regular estrus cycles, they failed to conceive. Bacterial endometritis is known to block conception due to pooling of mucus in the uterine lumen. Some bacteria, such as E. coli, P. aeruginosa and K. pneumoniae, produce biofilms that inhibit immune cellular clearance while adding to development of resistance to antimicrobial medications.
The study mares were split into 3 groups:
- Group I—15 mares were treated Intrauterine (IU) with 0.5% povidone solution then infused with 500 ml normal saline 6-8 hours later, followed by IM administration of 20 I.U. oxytocin within 10 minutes.
- Group II—15 mares were treated IU with 60 ml of 3% hydrogen peroxide then infused with normal saline and IM oxytocin in similar method to Group I.
- Group III—5 mares received only 500 ml IU normal saline and IM oxytocin 10 minutes later.
At the next estrus cycle, all mares were evaluated again with transrectal ultrasound and uterine cytology. If vaginal mucus cleared and neutrophil numbers were <2% and uterine edema ≤Grade 3, mares were covered twice at 36-hour intervals. Ultrasound diagnosis of pregnancy was then done at 21 days after the last breeding. Povidone iodine-treated mares conceived at a rate of 55.5%; hydrogen peroxide treated mares at a rate of 66.6%; and of two mares in the control group, one conceived.
Group I and II experienced a significant decrease in neutrophils and uterine edema following their treatment protocols; Group III did not. Vaginal mucus clearance similarly improved in Groups I and II compared to Group III.
Bacterial biofilms are degraded by hydrogen peroxide to differing degrees depending on the bacteria, and hydrogen peroxide also destroys bacteria through oxidative metabolism.
A weak solution of IU hydrogen peroxide was found to be beneficial for treatment in mares with uterine exudate. Dilute povidone iodine IU infusion has a long track record of resolving endometritis and improving conception rates.