Using mycobacterium cell wall fraction to decrease equine chorionic gonadotropin after abortion

BACKGROUND

Equine embryonic loss following the development of endometrial cups delays return to cyclicity due to the production of equine chorionic gonadotropin (eCG). Natural degradation of endometrial cups coincides with an influx of immune cells at 100-120 days of gestation, but therapeutic stimulation of reduced eCG production has been relatively unsuccessful. Recently, we observed an increase in pro-inflammatory cytokine production following the use of the immunostimulant mycobacterium cell wall fraction (MCWF).

OBJECTIVES

To evaluate the efficacy of hysteroscopic-guided injection of MCWF on the accelerated decline of eCG secretion.

STUDY DESIGN

In vivo experiment.

METHODS

Mares were pharmacologically aborted at 40-45 days of gestation, and then divided into groups: MCWF-treated (6 mg MCWF suspended in 20 mL LRS; n = 10) and Control (20 mL LRS; n = 6). Five days after abortion, hysteroscopic-guided injection of endometrial cups was performed, with 1 mL of volume placed into each visible endometrial cup. This was repeated 7 days later. Trans-rectal ultrasonography was performed to monitor ovarian activity, and serum was obtained to assess eCG and cytokine concentrations.

RESULTS

Concentrations of eCG decreased in the MCWF-treated group (p < 0.01) with a significant suppression noted as early as 14 days after onset of treatment and remained suppressed for the duration of the study. This coincided with an increase in peripheral IFN-γ (p < 0.01) and IL-1β (p < 0.01) concentrations. Eight out of ten MCWF-treated mares (80%) developed pre-ovulatory follicles, in comparison to 2/6 controls (33%). A pre-ovulatory follicle was noted 23 ± 4 days after onset of treatment.

MAIN LIMITATIONS

No pregnancy data was obtained following treatment.

CONCLUSIONS

This is the first report of a treatment for the accelerated reduction of eCG following abortion. Stimulation of this process allowed mares to develop a pre-ovulatory follicle within a month of MCWF treatment onset, granting repeat attempts at breeding within the confines of a single breeding season.

Detection of Chlamydia species in 2 cases of equine abortion in Switzerland: a retrospective study from 2000 to 2018

Species of genus Chlamydia are important pathogens of animals, with a worldwide distribution and broad host range. Some species, such as Chlamydia psittaci, also pose a zoonotic disease risk. Abortion is one of the many diseases that has been associated with chlamydial infections in animals, with most attention focused on the economic impacts to sheep production. The role of chlamydia in equine abortions is unknown. Using the family-specific 23S ribosomal RNA (rRNA) Chlamydiaceae real-time PCR, we tested 169 formalin-fixed, paraffin-embedded fetal membrane samples from 162 equine abortion cases collected between 2000 and 2018 in Switzerland. Two equine abortion cases (1.2%) tested positive for Chlamydiaceae. Further analyses by the species-specific 23S rRNA ArrayMate microarray and sequencing of a fragment of the 16S rRNA gene revealed C. abortus and C. psittaci. In both cases, equine herpesvirus 1 was also present, which might have been the abortion cause, alone or in synergy with Chlamydia. The prevalence of abortigenic chlamydial species in equine abortion cases in our study was significantly lower than rates described elsewhere. Zoonotic chlamydial agents present in equine fetal membranes nevertheless should be considered a potential risk to humans during foaling, abortion, or stillbirth.