Segmental Cervical Aplasia in a Colombian Creole Mare with Mosaic X-Chromosome Aneuploidy.
Authors: Pinzón-Osorio César Augusto, Cortés-Beltrán Daniela, Sanchez-Isaza Carlos Arturo, Jiménez-Robayo Ligia Mercedes, Lozano-Márquez Harvey, Zambrano-Varón Jorge, Jiménez-Escobar Claudia
Journal: Journal of equine veterinary science
Summary
# Editorial Summary A four-year-old Colombian Creole mare presented with an inability to drain uterine fluid during routine lavage therapy, prompting investigation into an apparent absence of cervical anatomy. Ultrasound confirmed normal ovarian structure with active follicular development, but revealed significant uterine distension with granular fluid consistent with mucometra; vaginal examination demonstrated that the vaginal canal terminated in a blind pouch with only a small papilla where the external cervical os should have been, establishing a diagnosis of segmental cervical aplasia. Cytogenetic analysis yielded mosaic X-chromosome aneuploidy with three distinct cell populations (63,X; 64,XX both at 45%; and 65,XXX at 10%), marking the first documented case of this congenital cervical defect occurring alongside cytologically confirmed aneuploidy and preserved ovarian function. The finding is significant because most cases of segmental cervical aplasia are associated with complete chromosomal aberrations rather than mosaic patterns, suggesting that mosaic aneuploidy may represent a milder or more variable genetic mechanism in reproductive tract development. Practitioners should maintain a high index of suspicion for congenital cervical defects in mares presenting with recurrent uterine fluid accumulation unresponsive to standard drainage protocols, and consider karyotyping when anatomical abnormalities are identified, as this knowledge influences both prognosis and breeding recommendations.
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Practical Takeaways
- •Absence of a detectable cervical external os during routine breeding evaluation or uterine treatment attempts warrants immediate investigation including ultrasound and vaginal endoscopy to rule out cervical aplasia
- •Mares with segmental cervical aplasia may retain normal ovarian function; cytogenetic analysis should be considered in cases of congenital reproductive tract abnormalities to identify chromosomal mosaicism that may inform prognosis and management
- •Reproductive tract anomalies may be associated with chromosomal abnormalities; affected mares are likely unsuitable for natural breeding but the presence of normal ovarian activity could theoretically allow consideration of assisted reproductive technologies if breeding is desired
Key Findings
- •A Colombian Creole mare presented with congenital segmental cervical aplasia where the external cervical orifice was absent and the vagina terminated in a blind pouch
- •Cytogenetic analysis revealed abnormal mosaic karyotype with three cell lines: 63,X (45%), 64,XX (45%), and 65,XXX (10%)
- •Despite cervical aplasia, the mare demonstrated regular ovarian activity with normal-sized ovaries showing structures suggestive of normal cyclicity
- •This is the first documented case of segmental cervical aplasia in a mare with confirmed X-chromosome mosaicism and concurrent ovarian function