Can Sperm Selection, Inseminating Dose, and Artificial Insemination Technique Influence Endometrial Inflammatory Response in Mares?

Comparison of systemic trimethoprim-sulfadimethoxine treatment and intrauterine ozone application as possible therapies for bacterial endometritis in equine practice

Bacterial endometritis is one of the major problems in equine reproduction and usually treated with antimicrobial drugs. The study aimed to compare the effects of intrauterine ozone application and systemic antibiotic treatment (trimethoprim-sulfadimethoxine) on intrauterine bacterial growth and possible side effects on the endometrium in a clinical setting. Mares (n = 30) with signs of endometritis (positive uterine bacterial culture and cytological findings) were assigned randomly to different treatments: intrauterine insufflation of an ozone-air-mix (240 ml, 80 μg ozone/ml) twice at a 48 h-interval (Ozone; n = 10), systemic antibiotic therapy with trimethoprim-sulfadimethoxine (30 mg/kg, p.o., twice daily) for 5 days (TMS; n = 10), or intrauterine insufflation of air (240 ml, sterile-filtered) twice at a 48 h-interval (air; n = 10). Endometrial biopsy for histological examination was obtained before the treatment. Histological examination revealed no differences among groups. A control examination, including transrectal ultrasound, bacterial culture, cytological evaluation, and biopsy, was performed 7 days after the last treatment. Overall bacterial growth was reduced in every group after the treatment (p < 0.05), irrespective of the therapy [Ozone: 4/9 (positive culture after treatment/number of mares), TMS: 3/10 and Air: 6/10; p > 0.05]. However, Ozone and TMS (p < 0.05) were more effective in reducing growth of gram-negative bacteria as compared to Air (p > 0.05). No effects on the number of polymorphonuclear granulocytes (cytology) were observed (p > 0.05). In conclusion, trimethoprim-sulfadimethoxine and intrauterine ozone insufflation are safe treatment options for bacterial endometritis in mares but the efficacy of both treatments in reducing bacterial growth did not result in a complete absence of intrauterine bacterial growth.

Uterine Inflammatory Response After Prostaglandin E1 (Misoprostol) Infusion Prebreeding or Immediately After Embryo Flushing in Commercial Donor Mares

Misoprostol, a synthetic PGE1, is becoming a common therapy for mares with suspected uterine tube obstruction. Recently, there have been concerns that uterine administration of misoprostol induces exacerbated uterine inflammation; however, this has not been critically evaluated. This study aimed to assess the inflammatory response and potential systemic reactions after uterine administration of misoprostol, either during prebreeding or immediately after postembryo flushing. Privately owned embryo donor mares (n = 11) were randomly assigned in a crossover design to receive misoprostol (3 mL +200 µg) or sham (3 mL of lactate Ringer's solution) infusions, bilaterally deposited via deep-horn, at least 72 hours prebreeding (experiment 1) or immediately after embryo flushing (experiment 2). Each mare had one cycle for misoprostol and sham in both experiments and a breeding cycle (no sham or misoprostol) between experiments. Uterine edema, fluid accumulation, and the number of uterine PMN were assessed before each infusion and then daily for 72 hours. Uterine lavage was performed the day after each infusion across groups and experiments. Ovulation was hastened with a GnRH agonist and confirmed at 24 hour-intervals. Mares were bred with semen from one of six stallions per owner's choice. Embryo flushing was performed 8 to 9 days postovulation. In either experiment, misoprostol did not affect uterine edema or fluid accumulation (P > .05). However, both the sham and misoprostol infusions increased the number of PMN up to 48 hours postinfusion in both experiments. Embryo recoveries were similar between sham (45%, 5/11) and misoprostol cycles in experiments 1 (45%, 5/11; P > .05) and 2 (sham, 68%, 7/11; misoprostol, 45%, 5/11; P > .05). In conclusion, misoprostol did not induce exacerbated uterine inflammation in mares or systemic adverse reactions when infused prebreeding or immediately after embryo flushing.

Sperm transport and endometrial inflammatory response in mares after artificial insemination with cryopreserved spermatozoa

This study aimed to determine whether the insemination site and dose with cryopreserved sperm of reproductively normal mares affect the sperm population in uterine tubes and the intensity of endometrial inflammatory response. Experimental subjects were estrous mares inseminated, in the mid-uterine body (Body) or the tip of the uterine horn (Tip), ipsilateral to the dominant follicle, with one 0.5 mL straw with 50 × 10⁶ sperm (50) or with eight straws with 50 × 10⁶ sperm/straw (400). Mares were slaughtered 2 h, 4 h and 12 h after artificial insemination (AI) and randomly assigned to following groups: Body 50 (n = 19) (2 h, 4 h or 12 h); Tip 50 (n = 29) (2 h, 4 h, or 12 h); Body 400 (n = 24) (2 h, 4 h, or 12 h); Tip 400 (n = 21) (2 h, 4 h, or 12 h). A Control group (n = 16) was not inseminated. After slaughter, uterine tubes were separated from uterus, and uteri and tubes flushed with phosphate-buffered saline (PBS). After flushing, an endometrial sample was collected from ipsilateral and contralateral horns and mid-uterus body for further histopathological examination. A sample of each uterine tube flushing was examined for sperm count, and a sample of each uterine flushing was used for polymorphonuclear neutrophils (PMNs) count. Data were analyzed using PROC GLM from SASv9.4. Insemination time, site, sperm dose, and their interactions were considered independent variables and sperm and PMNs numbers dependent variables. Deep horn insemination increased ipsilateral uterine tube sperm number without an increase in the inflammatory reaction compared with the uterine body insemination. The higher the insemination dose, the higher the uterine tubes' sperm number and inflammatory reaction, with a quicker resolution. In conclusion, the insemination site and dose affected sperm in the uterine tubes, while post-insemination time and dose influenced the inflammatory reaction.

Effects of Hysteroscopic and Uterine Body Insemination on the Presence of Selected Immune Cells in the Equine Endometrium

The effects of standard uterine body and hysteroscopic insemination on endometrial health were investigated. For this purpose, 33 mares were assigned to five different protocols: control (no insemination; n = 7), sham AI (sham uterine body insemination; n = 6), sham HysAI (sham hysteroscopic insemination; n = 7), standard AI (standard uterine body insemination, 300 × 10⁶ progressively motile sperms (PMS); n = 7) and HysAI (hysteroscopic insemination, 100 × 10⁶ PMS; n = 6). Sampling included uterine swabbing for microbiological examination, cytology for determination of polymorphonuclear neutrophils (PMNs) in the uterus, and endometrial biopsy collection for histology and characterization of endometrial immune cells on day 18 after ovulation (B1) as well as 8-10 hours (B2, day 20) and 72 hours after insemination (B3, day 23). Microbial contamination increased throughout the experiment in the sham insemination groups. Significant effects (P < .05) over time were detected for PMNs (cytology: sham HysAI, standard AI, and HysAI; histology: standard AI and HysAI), macrophages (immunohistochemistry: standard AI and HysAI) and T cells (immunohistochemistry: standard AI), showing an increase at B2 and a subsequent decrease toward baseline levels at B3. At B2, significant differences (P < .05) existed for PMNs (mean ± SEM) between control (1.3 ± 1.9%) and sham AI (2.2 ± 2.7%) versus standard AI (12.2 ± 4.7%) and for macrophages between control (4.1 ± 3.5%) and sham AI (2.5 ± 1.3%) versus standard AI (25.4 ± 15.8%). Thus, the cellular immune response of the endometrium depends on sperm deposition in the uterus and does not differ between hysteroscopic and standard uterine body insemination.