What is the best test for cryptorchidism?

Introduction

Cryptorchidism is a common heritable condition in horses and ponies and while retained testicles rarely release viable sperm, Leydig cells produce testosterone leading to undesirable stallionlike behaviour. Endocrine assays are frequently required to definitively diagnose retained testicular tissue.

Search method

A literature search of the Medline database was performed using the PubMed search engine. The search term ‘equine cryptorchidism’ was entered and the results filtered using the contents of the abstracts to retain articles relating specifically to diagnostic testing for cryptorchidism.

Quantity and quality of evidence

The initial search yielded 139 articles which after filtering were reduced to 6 articles included for analysis. Retrospective analysis of clinical cases comprising level IV evidence was used to evaluate the use of serum oestrone sulphate and serum testosterone (alone and after human chorionic gonadotropin (hCG) administration) for the detection of cryptorchidism [1]. Leung et al. [2] also analysed a large number of normal horses but few cryptorchid animals (n = 25, only 18 confirmed) were diagnosed using urine steroid profiling. The remaining prospective experimental studies evaluated the use of serum testosterone following administration of hCG [3], serum anti-Müllerian hormone (AMH) [4], serum androstenedione [5] and faecal oestrogens [6] to distinguish between gelded, entire and cryptorchid horses. This data was then variably extrapolated to provide inferred relevance for the use of each test for the detection of suspected cryptorchid animals. […]