Clinical, hormonal and ultrasonograph approaches to diagnosing cryptorchidism in horses

Cryptorchidism is a partial or total failure of testicular descent. For a proper diagnosis different methods are required. The main aim of this study was to compare different diagnostic methods. Sixty two horses (15 stallions, 32 cryptorchids and 15 geldings) were used in the experiment. They were clinically examined and ultrasonography was used to locate the testes. Blood samples were taken from the animals to measure the plasma level of testosterone and total estrogen (RIA method). In 22 horses suspected of cryptorchidism, the hCG stimulation test was performed. Blood samples were taken every 20 minutes for 8 hours and then 24 and 48 hours after injection. Clinical examination had a 60% success rate in detecting superficial and profound canal cryptorchids. Inguinal ultrasonography had a 100% rate of detection when the retained testes were in the area of the internal or external inguinal ring. The rate of detection with abdominal cryptorchids was 72.7%. The highest levels of testosterone were found in stallions' blood (2.3 ng/ml), they were lower in cryptorchids (0.68 ng/ml) and lowest in geldings (0.15 ng/ml). Total estrogen levels revealed a similar tendency (respectively: 395 pg/ml, 228 pg/ml and 26 pg/ml). Administration of hCG usually increased the level of testosterone from 0.68 ng/ml to 1.05 ng/ml 60 minutes after injection. We found that to successfully diagnose cryptorchids in veterinary practice a combination of clinical, ultrasonographic and hormonal examinations should be used.