Reproductive Ultrasound for Assessing Sperm Quality and Predicting Future Fertility Spermatozoa

A breeding soundness examination is commonly performed to examine the breeding potential of dogs. The procedure includes a clinical examination of the reproductive tract, observation of libido, the examination of semen quality, and in some cases ultrasound examination of the reproductive tract, and endocrine testing. Our work to date has utilized B-mode ultrasound to characterize the normal appearance of the testes and prostate gland and how these are disturbed in cases of pathology. Recently, we described digital image analysis of testicular and prostatic ultrasonographic echogenicity and heterogeneity in dogs and their relation to semen quality, and we characterized differences of testicular artery blood flow measured using Doppler ultrasonography in pre and post-pubertal dogs and in dogs with established infertility. In these and other studies, measures have been related to semen quality at the time of ultrasound examination, rather than future semen quality as would be expected based upon the time taken for spermatogenesis and sperm maturation. In this clinical study we performed detailed testicular artery blood flow measurements in normal fertile dogs, and evaluated whether these could predict future characteristics of semen quality. Thirty-one fertile dogs of two breeds (21 Labradors and 10 Golden retrievers) were used included. Three waves of a cardiac cycle were used to measure mean testicular artery values for peak systolic velocity (PSV), end-diastolic velocity (EDV), and these were used by the machine software to calculate resistance index (RI) and pulsatility index (PI). Additionally, total testicular volume (TTV) was calculated by combining the volume of each testis which was determined using the formula for an ellipse; volume = length x width x height x 0.5236. Between one and four semen collections were made between 62 and 183 days later, and total sperm output (TSO), percentage of sperm with normal live morphology (TLNS), and percentage of sperm with normal motility (TM) were measured in each individual assessment and then the mean TSO, mean TLNS and mean TM were calculated for analysis. All data were examined for normality and are described as mean ± one S.E. Relationships between RI, PI, TTV, and TSO, TLNS, and TM were investigated using linear regression with TSO, TLNS and TM as dependant variables. Data were analyzed using XLStat (Addinsoft, USA) and results were considered significant when P0.05). B-mode and Doppler ultrasound examination of the reproductive tract provides important and useful information about the state of the testes at the time of the examination. However, from this preliminary investigation, we were unable to detect any relationship between detailed measurements of either testicular size or testicular artery blood flow and future semen quality, although we note that the study was limited since semen quality was relatively unchanged in 18/31 dogs and changed (declined) in only 13/31 dogs. Further studies investigating the link between current ultrasonographic appearance and future quality of the ejaculate are warranted.