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During clinical evaluations, it may be difficult to distinguish between disturbances of testis function that reduce sperm output and increase sperm abnormalities compared to more severe disturbances of testis function that cause degeneration. Therefore a clinical diagnosis of degeneration is arbitrary. Degeneration does not necessarily reduce sperm concentration in the ejaculate, due to sperm accumulation in ampullae during sexual rest.

Ultrasonography is not necessarily clinically useful for distinguishing between normal testis tissue and tissue that has lost germinal epithelium [26]. When considerable fibrous tissue is present, testes may become more firm; however, a diagnosis of fibrosis is best accomplished with ultrasonography. Echographic anatomy of abattoir‐derived bull testes has been reported [27] and ultrasonography of testes does not affect semen quality [28]. Ultrasonography has been used to examine effects of testicular degeneration induced by scrotal insulation in bulls [4, 29, 30]; however, there were no evident visible changes in ultrasonograms after induced testicular degeneration. Furthermore, some studies failed to demonstrate significant correlations between computer analysis of ultrasonogram pixel intensity and semen quality, either during breeding soundness evaluations or after scrotal insulation [29, 31]. In other studies, echogenic changes induced by scrotal insulation preceded increased sperm abnormalities [4]; changes in pixel intensity accounted for 13–25% of variation in semen quality of ejaculates collected two to four weeks after ultrasonographic examination.