Application of Various Techniques in Localizing Retained Testes in Horses Before Cryptorchidectomy

• The determination of the exact location of the retained testes in cryptorchid horses before surgery has great clinical value.
• Cryptorchid horses can be evaluated safely, but need to be sedated before examination.
• Rectal palpation, percutaneous, and transrectal ultrasonography are preferred methods used to localize retained testes in horses.
• Combination of two or more techniques may need to be used in challenging cases.

Thorough clinical evaluation of cryptorchid horses and localizing the retained testis before surgery has great clinical value. Doing so will minimize unnecessary complications and prolonged anesthesia time from exploratory surgery in search of a retained testis in horses or the necessity to repeat invasive surgical procedures using a different approach. Heavy sedation and placement in stocks is recommended before the clinical evaluation. After the visual inspection of the inguinal region for the presence of previous surgeries, percutaneous inguinal ultrasound examination is often performed to visualize the testis or epididymis retained in the inguinal canal or at the external inguinal ring. The caudal abdomen and lateral aspect of the flank can also be systemically scanned in search for abdominal testes. Some veterinarians prefer to perform the palpation per rectum of all cryptorchid horses to determine if the vas deferens is entering the vaginal ring. This method helps in distinguishing between complete abdominal and incomplete abdominal cryptorchidism, but does not allow for the determination of the exact location of the retained testis. To visualize and measure retained testes, transrectal ultrasonography can be used. Since the majority of abdominal testes in stallions are found near the vaginal rings or urinary bladder, the ventral abdomen is scanned in a sweeping, medial to lateral, motion. The ultrasonographic tracing of the ampulla of the vas deferens per rectum is the author's preferred method of detecting retained testes in horses. More than one diagnostic method is often used in the most challenging cases.