Researchers evaluated an easier blood test to diagnose cryptorchids. Cryptorchidism (the failure of one or both testicles to descend properly) has been recognized in the horse and is thought to occur in roughly 5-8% of male foals and is most often unilateral (one side undescended). Horses with one retained testicle can often be fertile, with bilateral cryptorchids (both testicles retained) often being sterile. The cells of the testis that are responsible for testosterone production often continue to produce testosterone regardless of where the testicles are located (inguinal or within the abdomen), with these horses often exhibiting stallion-like behavior.
The diagnosis of a cryptorchid is oftentimes complicated by an uncertain history, especially if one testicle has been removed by prior surgery, such that behavioral history becomes very important in considering whether a retained testicle may be an issue. Other methods for diagnosis include rectal palpation, ultrasound, exploratory surgery, and measurement of blood hormone levels. Anti- Müllerian hormone (AMH) is a glycoprotein that is secreted from the fetal testis by the Sertoli cells and continues to be secreted by these cells throughout the male horse’s life.
The aim of this study was to “evaluate the usefulness of serum AMH as a biomarker for diagnosis of cryptorchidism in horses”. Blood was drawn from stallions, hemi-castrated (one testicle removed), unilateral cryptrochids, and geldings, and the AMH levels were measured and compared. AMH was found in the blood of the stallions and the unilateral cryptorchids but not at any detectable level in the geldings. The researchers concluded, “the cryptorchid testis after hemi-castration secretes AMH, and that serum AMH concentrations may be a useful biomarker for diagnosis of equine cryptorchidism.”
This particular test requires only one blood draw, therefore, only one visit by the veterinarian. The lab test utilized in this study to measure the AMH is AMH Gen II ELISA, #A73818 by Beckman Coulter, Inc. Brea, CA.
Scientific Article: Harutaka, M et al “Anti-Müllerian hormone as an indicator of hemi-castrated unilateral cryptorchid horses”, J. Equine Sci. Vol. 26, No. 1, pp. 15-20, 2015.