Assessment of Dog Testis Perfusion by Colour and Pulsed-Doppler Ultrasonography and Correlation With Sperm Oxidative DNA Damage

Abstract

The assessment of testicular artery blood flow by colour and pulsed-Doppler ultrasonography is an important diagnostic technique to assess vascular perfusion. Recently, it has been suggested as a good predictor of sperm quality. On the other hand, through the alkaline Comet Assay, it is possible to quantify sperm oxidative DNA damage. The aim of this study was to evaluate the relationship between routine sperm parameters, testicular artery blood flow and oxidative DNA damage in canine sperm. Testicular ultrasonography and sperm collection were performed on 12 male dogs, with the animals being allocated into 2 groups, according to the classification of the ejaculates' quality, as normozoospermic (N; n = 7) or non-normozoospermic (OAT; n = 5). Seven dogs aged between 1.5 and 8.0 years old were included in group N and 5 dogs, aged between 2.0 and 11.0 years old, were included in group OAT. The sperm-rich fraction of the ejaculates was evaluated for sperm routine parameters and DNA damage by comet assay. Colour and pulsed-Doppler ultrasonography were used to evaluate the blood flow of the supratesticular and marginal arteries of right and left testis. Group OAT presented higher levels of sperm oxidative DNA damage (A.U.) in comparison to group N (N:11.7 ± 9.9; OAT:34.2 ± 6.1; P< .001). The peak of systolic velocity was positively correlated with sperm concentration (r = 0.685; P= .005). The resistive and pulsatility indexes (RI and PI) of the supratesticular artery were negatively correlated with sperm membrane integrity (HOST⁺) (r = -0.594; P = .042; r = -0.612; P = .035, respectively). The end diastolic velocity (EDV) of the supratesticular artery was positively correlated with sperm concentration (r = 0.748; P = .005) and negatively correlated with sperm oxidative DNA damage (r = -0.766; P = .004). Our results suggest that the assessment of the testicular artery blood flow by colour and pulsed-Doppler ultrasonography could be a good predictor of sperm quality in dogs in terms of sperm concentration, membrane integrity and sperm oxidative DNA damage.

Keywords: comet assay; dog, Doppler; oxidative DNA damage; sperm; testicular perfusion.