Semen collection, sperm characteristics and ultrasonographic features of reproductive tissues in crab-eating fox (Cerdocyon thous)

Our objective was to condition adult male crab-eating fox (Cerdocyon thous) to allow semen collection by digital manipulation of the penis, assess sperm characteristics, and use ultrasonography to assess and measure testes and prostate and determine echotexture, as well as hemodynamics of testicular and spermatic cord arteries. Five captive C. thous (2-5 y, ∼7 kg) were used. After conditioning for digital sperm collection, 13 ejaculates were obtained from two males. Ejaculate characteristics (mean ± SD) were volume (393.2 ± 178.0 μL), concentration (463.7 ± 594.4 × 106 sperm/mL), total sperm number (217.4 ± 304.0 × 10⁶ sperm), total motility (68.0 ± 6.1%), progressive motility (48.8 ± 5.1%) and rapid sperm (57.2 ± 6.8%). The most prevalent sperm morphological defects were abnormal acrosome, small abnormal head, and diadem defect. Under chemical restraint, testes and prostate were evaluated with B-mode and spectral Doppler ultrasonography. Based on ultrasonography, testicular volumes were (2.2 ± 0.7 and 2.1 ± 0.7 cm³ for left and right testes, respectively), whereas prostate dimensions were 2.3 ± 0.4 cm long and 1.5 ± 0.3 cm thick. Lastly, using triplex Doppler, peak systolic velocity (PSV) was higher in testicular versus intratesticular arteries. In conclusion, adult male C. thous were conditioned to allow sperm collection by digital manipulation without urine contamination, enabling evaluation of sperm characteristics. Furthermore, B-mode ultrasound facilitated evaluation of testes and prostate morphometry and echotexture, whereas Doppler was used to characterize testicular blood flow. This was proof of concept for semen collection and baseline data for future male reproductive soundness examinations and development of assisted reproductive techniques in this species.