Urogenital Hypoplasia and X Chromosome Monosomy in a Draft Horse Filly.
Authors: Hahn Kirsten, Conze Theresa M, Wollanke Bettina, Distl Ottmar, Goehring Lutz S, Witte Tanja S
Journal: Journal of equine veterinary science
Summary
A 5-month-old draft horse filly presented with progressive incontinence and severe perivulvar dermatitis, prompting investigation that revealed a left-sided ectopic ureter draining into the caudal vagina, cervical hypoplasia, and urine pooling within the uterus—abnormalities managed surgically via left ureter-nephrectomy. Cytogenetic analysis unexpectedly identified XO monosomy with a 63,X/64,XX mosaic pattern, representing the first documented case linking chromosomal abnormality to ectopic ureter in draft horses. The concurrent presence of multiple urogenital developmental defects—ectopic ureter, cervical hypoplasia, and uterine changes—alongside sex chromosome monosomy suggests a potential genetic aetiology rather than isolated anatomical malformation. Beyond this individual case, the findings underscore the clinical value of karyotyping in any mare presenting with developmental abnormalities affecting the cervix, uterus, or ovaries, or exhibiting reproductive tract irregularities and oestrous dysfunction. For practitioners managing young fillies with incontinence or perivulvar disease refractory to conventional management, chromosomal analysis warrants consideration alongside conventional diagnostic imaging and endoscopy, particularly when structural anomalies are identified.
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Practical Takeaways
- •Incontinence and perivulvar dermatitis in young fillies should prompt investigation for ectopic ureter and other urogenital developmental abnormalities via endoscopic examination.
- •Chromosome abnormalities should be suspected in fillies presenting with multiple developmental abnormalities of reproductive tract structures; cytogenetic testing is recommended for diagnostic confirmation.
- •Surgical intervention (ureter-nephrectomy) may be necessary to manage complications of ectopic ureter, but underlying chromosomal causes must be identified to guide management decisions and breeding recommendations.
Key Findings
- •A 5-month-old draft horse filly presented with incontinence and severe perivulvar dermatitis secondary to left-sided ectopic ureter.
- •Cytogenetic examination revealed XO monosomy with 63,X/64,XX mosaic karyotype, the first reported in a draft horse with ectopic ureter.
- •Associated findings included cervix hypoplasia and urine accumulation in the uterus, managed surgically via left ureter-nephrectomy.