Hemodynamic evaluation of the testicular artery in stallions with spermatic cord torsion

Abstract

Testicles are supported by spermatic cord and show some mobility within the scrotum. Excessive testicle mobility can result in rotation around its vertical axis, which may result in cord strangulation and reduction of blood perfusion (Filho and Oliveira, ABCMED. 2012). Depending on duration and severity of torsion, a reduction in diastolic velocity or retrograde diastolic flow may happen and lead to the absence of arterial flow, as a result of increased resistance to blood flow (Dogra et al., Journal of Clinical Ultrasound. 2001;29:105-108). Retrograde diastolic blood flow has been detected in stallions with 180° spermatic cord torsion (Pozor and McDonnel, Theriogenology. 2004;61:799-810). The objective of the present study was to evaluate testicular artery blood flow in stallions with 180° spermatic cord torsion in comparison to stallions with testis not affected by spermatic cord torsion. Both testis of 38 Mangalarga Marchador stallions were evaluated by spectral Doppler ultrasound. Animals with normal testis were divided into two experimental groups according to their age to verify if there would be any differences between groups: Normal Young, 30 months-4 years old (NY, n=10) and Normal Adults, 6-9 years old (NA, n=10). Similarly, animals with unilateral 180° spermatic cord torsion were divided into: Young with torsion, 30 months-4 years old (TY, n=10) and Adults with torsion, 6-9 years old (TA, n=8).For Doppler evaluations, spectral mode, resistance and pulsatility indexes (RI and PI, respectively), systolic peak velocity (SPV), end-diastolic velocity (EDV) and timed average mean maximum velocity (TAMMV) were measured at the supratesticular (Supra) and capsular (Cap) arteries. Stallions were evaluated during the reproductive season and were restrained without sedation. For statistical analysis, overall effect and pairwise testing with Šidák correction was performed. The effect of the predictor variables presence of torsion, age group and side were assessed using mixed models, Pearson correlations were also applied to assess the association between pairs of variables. For young stallions, when normal testis (n=20) were compared to rotated testis (n=15) and contralateral (n=5), rotated testis showed lower Supra RI than normal testis (P<0.001). For adult stallions, contralateral testis (n=7) Supra EDV were lower than normal testis (n=20) (P<0.001). Findings showed blood flow changes due to torsion in rotated testis and its contralateral. Therefore, these parameters should be considered to assess damage caused by torsion of the spermatic cord because of impaired testicular perfusion. Findings reinforce the theory of a reduced blood perfusion not only for the rotated testicles, but also for the contralateral one.