Monorchidism in the horse.
Abstract: Six horses with monorchidism, identified at surgery for cryptorchidectomy, are reported. All six presented with a single scrotal testis. Following surgical removal of one testis, they were either hormonally, anatomically or behaviourally determined to be geldings. Three other horses reported in the literature are reviewed. Of these nine cases of monorchidism, eight were thought to be caused by testicular degeneration and one by testicular agenesis. The vaginal process was present in all of the former and absent in the latter. The left side was involved in five of these eight horses. In seven, the epididymis was absent and, in the remaining two, only the epididymal tail was present. The condition was thought to be congenital in the six horses in this series. A surgical approach to identify accurately monorchid horses is described.
Publication Date: 1989-05-01 PubMed ID: 2567234DOI: 10.1111/j.2042-3306.1989.tb02150.xGoogle Scholar: Lookup
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- Journal Article
Summary
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This research article discusses a study in which six instances of monorchidism in horses were identified during surgery for cryptorchidectomy. Based on the surgery results and further anatomical, hormonal, or behavioral assessments, the horses were considered geldings. A review of three similar instances in past literature was also conducted, providing a total analysis of nine cases. Most cases were a result of testicular degeneration, while a single instance was due to testicular agenesis. Other findings, such as the prevalent involvement of the left side or absence of epididymis, are also discussed.
Methodology and Cases
- The research observed six horses that were identified with monorchidism during a cryptorchidectomy surgery. Cryptorchidectomy is a surgical procedure that removes undescended testis in male animals, in this case, horses.
- After surgically removing one testicle, the conditions of these horses were further examined through hormonal checks, anatomical observations, or monitoring their behavior.
- The study also revisited three similar cases that have been previously reported in other research literature. These additional cases were included to build a relatively larger sample size, and thereby enhance the comprehensiveness of the study.
Findings
- Upon analyzing all nine cases, researchers found that eight of the horses had monorchidism as a result of testicular degeneration. Only one horse had testicular agenesis.
- All eight horses suffering from testicular degeneration had the vaginal process present. However, it was absent in the horse with testicular agenesis.
- Furthermore, five out of eight cases showed symptoms developing on the left side of their reproductive anatomy.
- Seven out of nine horses were lacking the epididymis, a duct behind the testis where sperm is stored. In the remaining two, only the tail of the epididymis was present, indicating a deficiency in the quantity or quality of the sperm.
Conclusions
- Horses in this study were all deemed congenital monorchids, implying that their conditions were present from the time of their birth.
- The study goes on to recommend a surgical approach that can help dissect and investigate this condition in horses with greater accuracy.
Cite This Article
APA
Parks AH, Scott EA, Cox JE, Stick JA.
(1989).
Monorchidism in the horse.
Equine Vet J, 21(3), 215-217.
https://doi.org/10.1111/j.2042-3306.1989.tb02150.x Publication
Researcher Affiliations
- Department of Large Animal Clinical Sciences, Michigan State University, East Lansing 48824.
MeSH Terms
- Animals
- Cryptorchidism / surgery
- Cryptorchidism / veterinary
- Horses / abnormalities
- Horses / surgery
- Male
- Orchiectomy / veterinary
- Testis / abnormalities
Citations
This article has been cited 1 times.- Sinovich M, Monné Rodriguez J, Pieńkowska-Schelling A, Schelling C, Kelly PG. An Unusual Case of a Monorchid Horse with an Abdominally Retained Testicle. Sex Dev 2025 Apr 8;19(1):1-9.
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