Antimicrobial resistance of endometrial bacterial isolates collected from UK Thoroughbred mares between 2014 and 2020

BACKGROUND

Antimicrobial resistance (AMR) is important in equine reproduction, as antimicrobials have historically been widely used in the management of breeding mares. However, evidence of the characteristics of AMR in uterine isolates is limited in the UK. The objective of this retrospective study was therefore to describe temporal changes in AMR patterns of bacteria isolated from the endometrium of Thoroughbred broodmares in south-east England between 2014 and 2020.

METHOD

Endometrial swabs were processed for microbiology and antimicrobial susceptibility testing (AST). For frequently isolated bacteria, changes in AMR patterns over time were assessed using a logistic regression model.

RESULTS

From 18,996 endometrial swabs, 30.5% were positive for microbial culture. AST was performed on 2091 isolates, representing 1924 swabs collected from 1370 mares located at 132 premises. Beta-haemolytic Streptococcus (BHS, 52.5%) and Escherichia coli (25.8%) were most frequently isolated. In BHS, resistance to enrofloxacin (p = 0.02), nitrofurazone (p < 0.001) and oxytetracycline (p < 0.01) increased significantly between 2014 and 2020, while resistance to trimethoprim-sulfamethoxazole (p < 0.001) decreased. In E. coli, resistance to nitrofurazone increased (p = 0.04) and resistance to gentamycin (p = 0.02) and trimethoprim-sulfamethoxazole (p < 0.001) decreased.

LIMITATIONS

Variations in the specimen collection protocols might have affected the frequency of isolates detected.

CONCLUSION

Between 2014 and 2020, AMR changed in this bacterial population. However, there was no significant increase in resistance to penicillin (99.6% BHS susceptible), gentamycin (81.7% E. coli susceptible) or ceftiofur.

Equine Coital Exanthema: New Insights on the Knowledge and Leading Perspectives for Treatment and Prevention

Equine coital exanthema (ECE) is a highly contagious, venereally-transmitted mucocutaneous disease, characterized by the formation of papules, vesicles, pustules and ulcers on the external genital organs of mares and stallions, and caused by equid alphaherpesvirus 3 (EHV-3). The infection is endemic worldwide and the virus is transmitted mainly through direct contact during sexual intercourse and by contaminated instruments during reproductive maneuvers in breeding facilities. The disease does not result in systemic illness, infertility or abortion, yet it does have a negative impact on the equine industry as it forces the temporary withdrawal of affected animals with the consequent disruption of mating activities in breeding facilities. The purpose of this review is to provide up-to-date relevant information on the knowledge of EHV-3 infection and to analyze new approaches on diagnostics, treatment and prevention in the interest of minimizing the negative consequences of ECE in light of the current situation of the equine industry.

Fetal morphological features and abnormalities associated with equine early pregnancy loss

BACKGROUND

Early pregnancy loss (EPL) occurs in approximately 8% of equine pregnancies, although the aetiology is mostly unknown and embryonic/fetal morphological abnormalities associated with EPL are not defined.

OBJECTIVES

To compare the morphology of EPL to clinically normal embryos/fetuses and previously described embryonic/fetal developmental milestones. To identify morphological abnormalities associated with equine EPL.

STUDY DESIGN

Observational case-control study.

METHODS

Embryos/fetuses were obtained from clinically normal Thoroughbred and pony pregnancies (n = 11) and following EPL from Thoroughbred mares (n = 27). The crown-rump length (CRL) of embryos/fetuses was measured and macroscopic morphology and developmental age were determined independently by three blinded examiners. Sagittal sections of EPL (n = 13) and control (n = 6) embryos/fetuses were assessed microscopically. Fisher's exact test was used to determine significance (P < .05) and correlations were expressed by Pearson coefficient.

RESULTS

Age and CRL were strongly positively correlated in clinically normal Thoroughbred and reference (n = 15, R = .9 (95% CI: 0.8-1.0), R²  = .9, P < .0001) but not EPL embryos/fetuses (n = 19, R = .1 (95% CI: -0.4 to 0.5), R²  = .01, P = .75). Relative to controls, the CRL of EPL embryos/fetuses was smaller, with evidence of intrauterine growth retardation (IUGR) in 3/8 fetuses assessed. In 9/13 EPL embryos/fetuses, nonspecific neural tissue alterations were identified including disruption of developing pros-, mes- and rhombencephalon and the presence of haemosiderin, indicating premortem haemorrhage. Failed neural tube closure was identified in 1/13 EPL embryos/fetuses. Subcutaneous haemorrhage was present in 14/27 EPL embryos/fetuses.

MAIN LIMITATIONS

Autolysis significantly affected 15/27 EPL embryos/fetuses, excluding them from complete assessment. The IUGR reference cut-off values were based on a small number of controls.

CONCLUSIONS

Morphological features associated with equine EPL were a mismatch between embryonic/fetal size and age, and alterations of the developing neural tissue and localised subcutaneous haemorrhage. Failed neural tube closure was confirmed as a rare specific abnormality.

Coconut Water as an Extender Component for Cooled Equine Sperm

The aim of this study was to evaluate the effect of coconut water as a component of extender in different formulations for cooling equine sperm. One ejaculate of fourteen stallions was collected. Sperm was diluted to 50 × 10⁶ sperm/mL using five different extenders: ACP-105: powdered coconut water extender (ACP-105, ACP Biotecnologia, Brazil); ACP-Milk: ACP-105 + 20 g/L of skimmed milk; ACP-EY 2.5%: ACP-105 + 2.5% of egg yolk; ACP-EY 5%: ACP-105 + 5% of egg yolk; and BotuSêmen (Botupharma, Botucatu, Brazil) and cooled in passive cooling device (BotuFlex, Botupharma, Botucatu, Brazil) at 5 and 15°C for 24 hours. Sperm kinetics and plasma membrane integrity (PMI) were evaluated by computer-assisted sperm analysis and fluorescence staining, respectively, at T0 (before cooling) and T24 (24 hours after cooling). Sperm kinetics did not differ at T0 among groups (P > .05); however, at T24, these parameters were significantly lower in ACP-105 (5°C, total motility [TM]: 9.2 ± 3.6%; progressive motility [PM]: 2.7 ± 1.6%; percentage of fast-moving spermatozoa [RAP]: 4.8 ± 3.0%; 15°C, TM: 10.6 ± 3.0%; PM: 1.1 ± 0.5%; RAP: 4.8 ± 1.9%) and ACP-EY 5% (5°C, TM: 28.0 ± 6.3%; PM: 5.7 ± 1.8%; RAP: 15.9 ± 6.0%; 15°C, TM: 30.0 ± 6.0%; PM: 6.9 ± 2.1%; RAP: 17.6 ± 5.3%) compared with BotuSêmen (5°C, TM: 66.2 ± 5.6%; PM: 21.1 ± 2.8%; RAP: 53.9 ± 6.1%; 15°C, TM: 63.4 ± 5.4%; PM: 17.2 ± 2.8%; RAP: 51.4 ± 6.3%) (P < .05). All groups exhibited similar PMI at tested moments and cooling temperatures (5°C: 83%; 15°C: 84%) (P > .05). Further studies are necessary to evaluate powdered coconut water in different compositions of sperm extender; however, coconut-based extender as used in this study was not an alternative to preserve sperm parameters of cooled equine sperm.

Foaling rate of mares that were rebred after pregnancy loss in Hidaka, Japan

The purpose of this study was to evaluate foaling rates of mares that were rebred after the pregnancy loss in same reproductive season and to examine factors influencing them in Hidaka, Japan. The study included 82 Thoroughbred mares that had experienced pregnancy loss. The foaling rate of the mares that were rebred after pregnancy loss was 57.3%. The foaling rate decreased as the period until detection of pregnancy loss increased. Aging and lower body condition score of mares decreased the foaling rate.