Doppler ultrasound proves worth in identifying testicular problems in stallions

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The three locations along the testicular artery that were assessed, and the angle at which the handpiece (transducer) was held. A. The spermatic cord: Supratesticular artery; B. Close to the tail of epididymis: the capsular artery; C. Within the parenchyma: intratesticular artery. Modified image from the book "Ultrasonic imaging and animal reproduction: Color-Doppler ultrasonography," O.J. Ginther.
The three locations along the testicular artery that were assessed, and the angle at which the handpiece (transducer) was held. A. The spermatic cord: Supratesticular artery; B. Close to the tail of epididymis: the capsular artery; C. Within the parenchyma: intratesticular artery. Image: Modified image from the book Ultrasonic imaging and animal reproduction: Color-Doppler ultrasonography, by O.J. Ginther.

Pulse Doppler ultrasound has been shown by researchers to be a valuable tool for diagnosing stallions with testicular dysfunction.

Doppler ultrasound, used to measure blood-flow parameters, proved to be a good predictive tool for sperm quality, the study team from Spain reported in the open-access peer-reviewed journal, PLOS ONE.

Testicular function is highly dependent on good blood flow. In fact, disturbances to blood flow are among the most common causes of poor fertility in male horses.

Testicular function is particularly susceptible to blood vessel injury, impacting on sperm production and the quality of the ejaculate.

Cristina Ortega Ferrusola and her colleagues said prompt diagnosis of testicular problems enabled appropriate treatment, thus improving fertility forecasts for stallions.

The researchers from a range of tertiary institutions in Spain set out to assess the effectiveness of Doppler ultrasonography in diagnosing stallions with testicular dysfunction and to see whether there was a relationship between the ultrasound findings for the testicular artery and sperm quality.

Ten stallions were used, seven of which were consider fertile and three of which were considered sub-fertile.

Two ejaculates per stallion were collected and preserved for later analysis.

Doppler blood-flow parameters were measured at three different locations along the testicular artery – at the supratesticular artery, the capsular artery and the intratesticular artery.

Using the ultrasound technology, they were able to assess the resistive index, pulsatility index, peak systolic velocity, end diastolic velocity and time average maximum velocity, as well as the total arterial blood flow and its rate.

The study team reported that the capsular artery proved the most reliable location to carry out the assessment, since blood flow parameters of this artery proved to be most closely related to sperm quality.

“Significant differences in all the Doppler parameters studied were observed between fertile and subfertile stallions,” the researchers reported.

The fertile stallions returned results that showed good blood delivery. In contrast, sub-fertile stallions tended to present results pointing to high vascular resistance – that’s poorer blood delivery.

The study team was able to provide cut-off values to identify fertile stallions from those with testicular dysfunction.

Spectral Doppler ultrasound was a good predictive tool for sperm quality, they concluded.

“Doppler ultrasonography could be a valuable diagnostic tool for use by clinical practitioners for the diagnosis of stallions with testicular dysfunction and could be a viable alternative to invasive procedures traditionally used for diagnosis of sub-fertility disorders.

“This study,” they said, “provides a firm basis for the introduction of Doppler ultrasound into stallion breeding soundness evaluations and indicates that it should be performed in all stallions with pathologies and sperm analysis abnormalities.

“Valuable stallions should be monitored regularly to try and identify subtle changes in blood flow over time.”

The study team comprised Ortega Ferrusola, Jose Ortiz-Rodriguez, Luis Anel-Lopez, Patricia Martín-Muñoz, Mercedes Álvarez, Gemma Gaitskell-Phillips, Luis Anel, Pedro Rodríguez-Medina, and Fernando Peña.

Ortiz-Rodriguez JM, Anel-Lopez L, Martín-Muñoz P, Álvarez M, Gaitskell-Phillips G, Anel L, et al. (2017) Pulse Doppler ultrasound as a tool for the diagnosis of chronic testicular dysfunction in stallions. PLoS ONE 12(5): e0175878. https://doi.org/10.1371/journal.pone.0175878

The study, published under a Creative Commons License, can be read here

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