Evaluation of testicular artery blood flow by Doppler ultrasonography as a predictor of spermatogenesis in the dog

Melatonin Administration Enhances Testicular Volume, Testicular Blood Flow, Semen Parameters and Antioxidant Status during the Non-Breeding Season in Bafra Rams

Our objectives were to investigate the effects of exogenous melatonin on testicular volume (TV), testicular blood flow (TBF), and semen quality in Bafra rams during the non-breeding season. One group of rams (MEL, n = 5) received a 36 mg melatonin implant twice, with 30 days in between, while the other group (CON, n = 5) served as the control. TBF, TV, and semen quality parameters were determined at three-week intervals starting three weeks before until twelve weeks after the first melatonin implant. Testicular blood flow was determined in the supratesticular (STA) and marginal testicular artery (MA) using color Doppler ultrasound. Semen was collected and evaluated, and the total oxidative status (TOS) and total antioxidative status (TAS) was determined using an ELISA. The MEL group had increased (p < 0.05) TV between the sixth and twelfth week after the start of treatment. Overall, the MEL group had lower resistance and pulsatility indexes (p < 0.05) between the third and ninth week, although there was no difference (p > 0.05) between the two groups in most semen quality parameters. However, TAS concentrations increased (p < 0.05) in the MEL group compared with the CON. The results of this study show that exogenous melatonin in the non-breeding season significantly increased both TBF and TV in Bafra rams. Therefore, giving rams implants with 36 mg melatonin twice at least one month prior to the non-breeding season is expected to improve testicular size and function and reproductive capacity.

Ultrasound-Based Technologies for the Evaluation of Testicles in the Dog: Keystones and Breakthroughs

Ultrasonography is a valuable diagnostic tool extensively used in the andrology of human and domestic animals, including dogs. This review aims to provide an overview of various technologies based on ultrasound, from the basic B-Mode ultrasonography to the more recent advancements, such as contrast-enhanced ultrasonography (CEUS) and ultrasound elastography (UEl), all of which are utilized in the evaluation of canine testicles. The review outlines the principles behind each of these technologies and discusses their application in assessing normal and abnormal testicular conditions. B-mode canine testicular ultrasonography primarily focuses on detecting focal lesions but has limitations in terms of objectivity. Other technologies, including Doppler ultrasonography, B-Flow, and CEUS, allow for the characterization of vascular patterns, which could be further measured using specific applications like spectral Doppler or quantitative CEUS. Additionally, ultrasound elastography enables the assessment of parenchyma stiffness both qualitatively and quantitatively. These ultrasound-based technologies play a crucial role in andrology by providing valuable information for evaluating testicular function and integrity, aiding in the identification of pathological conditions that may impact the health and quality of life of male dogs.

Does Size Matter? Testicular Volume and Its Predictive Ability of Sperm Production in Rams

Over the years, testicular volume has been used to evaluate the reproductive capacity of rams and the effects of different factors related to reproductive performance. The aim of this study was to determine the most suitable tool and formula to calculate testicular volume under field conditions to guarantee a more accurate determination of sperm production. First, testicles from 25 rams (n = 50) were measured in vivo and postmortem using calipers and ultrasonography during the breeding season (BS). The accurate testicular volume (ATV) was calculated through water displacement. In addition, the sexual status of donor rams was evaluated during a period of four years in a reproduction center, and the three most crucial groups in terms of genetic value and seminal collections were studied in the second part of this experiment: ER-NBS (Elite rams during the non-breeding season), ER-BS-S (Elite rams with a standard frequency of seminal collection), and ER-BS-O (Elite rams with a high frequency of seminal collection). The total testicular volume (TTV), testosterone (T), and total spermatozoa obtained from two consecutive ejaculates in the same day (SPERM) were measured, and the relationship between SPERM and TTV and T was analyzed to predict SPERM. Although all published formulas revealed statistically significant differences (p ≤ 0.05) from the ATV, our proposed formula (ItraULE) (Testicular volume = L × W × D × 0.61) did not show significant differences. In the second part of the study, in the ER as a model donor ram for its high genetic value and high demand from farmers, TTV and T showed strong positive correlations with SPERM (r = 0.587, p = 0.007 NBS; r = 0.684, p = 0.001 BS-S; r = 0.773, p < 0.0001 BS-O). Moreover, formulas were established to predict SPERM in these practical scenarios. In conclusion, the use of ultrasonography and a new formula adapted to rams could improve the prediction of SPERM considering crucial factors such as season and semen collection frequency.

Ovine fertility by artificial insemination in the breeding season could be affected by intraseasonal variations in ram sperm proteomic profile

It is important to note that seasonality could affect ram reproductive parameters, and therefore, fertility results after artificial insemination. In this work, 1) we assessed fertility rates after cervical artificial insemination of 11,805 ewes at the beginning (June 21st to July 20th) and at the end (November 20th to December 21st) of the reproductive season in the Assaf breed for the last four years, and 2) we aimed to identify male factors influencing the different reproductive success obtained depending on the time at the mating season in which ovine artificial insemination was performed. For this purpose, we evaluated certain ram reproductive and ultrasonographical parameters as well as we performed a multiparametric and proteomic sperm analysis of 6-19 rams at two very distant points in the mating season (July as Early Breeding Season -EBS- and November as Late Breeding Season -LBS-). Rutinary assessments carried out in the ovine reproduction centers (testicular volume, libido, sperm production and mass motility) showed non-significant differences (P ≥ 0.05) between both studied times, as well as the ram ultrasonographic evaluation (Resistive and Pulsatility Index as Doppler parameters; and pixels mean gray level, and hypoechoic areas percentage and density as echotexture parameters). However, at level of sperm functionality, although sperm quality appeared non-significantly lower (P ≥ 0.05) in the EBS, we identified a significantly different (P < 0.05) sperm proteomic profile between the seasonality points. The following proteins were identified with the lowest abundance in the EBS with a fold change > 4, a P = 2.40e-07, and a q = 2.23e-06: Fibrous Sheath-Interacting Protein 2, Disintegrin and Metalloproteinase Domain-Containing Protein 20-like, Phosphoinositide-Specific Phospholipase C, Tektin 5, Armadillo Repeat-Containing Protein 12 Isoform X3, Solute Carrier Family 9B1, Radial Spoke Head Protein 3 Homolog, Pro-Interleukin-16, NADH Dehydrogenase [Ubiquinone] 1 Alpha Subcomplex Subunit 8, Testis, Prostate and Placenta-Expressed Protein, and Acyl Carrier Protein Mitochondrial. In conclusion, while our basic analyses on male and sperm quality showed similar results between the beginning and the end of the breeding season, on a proteomic level we detected a lower expression of sperm proteins linked to the energy metabolism, sperm-oocyte interactions, and flagellum structure in the EBS. Probably, this different protein expression could be related to the lower fertility rate of Assaf ewes after cervical artificial insemination at this time. More importantly, sperm proteins can be used as highly effective molecular markers in predicting sperm fertilization ability related to intraseasonal variations.

Doppler Examination of the Testicular Artery of Beagle-Breed Dogs from Birth to Puberty

The objectives were (a) the study of haemodynamic parameters of blood flow within the testicular artery, (b) the assessment of differences in these parameters at different segments of the artery (i.e., sequentially, as the artery flows through different regions of the testis), and (c) the identification of potential associations with measures of testicular maturation. Eight healthy beagle-breed male dogs were monitored at fortnightly intervals from the 4th to the 40th week of life, by using clinical, seminological, and ultrasonographic (B-mode, pulsed-wave Doppler) examinations. Haemodynamic parameters were assessed at four different segments of the testicular artery: at the distal supra-testicular, the marginal testicular at the cranial pole of the testis, the marginal testicular at the caudal pole of the testis, and the intratesticular. The study period was divided into three time slots (pre-puberty, puberty, and post-puberty) depending on testicular maturation and sperm production. No clinically evident abnormalities were seen in any animal throughout the study. Semen ejaculates were first collected on the 28th week, and spermatozoa were first seen on the 30th week of life. The results of B-mode examination indicated that in all dogs, the echogenicity of the testicular parenchyma was homogeneous. The waveforms of the blood flow in the testicular artery were monophasic with systolic peaks, low diastolic flow, and low vascular resistance. Most cases of significant differences between the three age periods were noted for the comparison of the pre-pubertal to pubertal periods (n = 11); among the parameters studied, the blood volume (n = 9) showed most instances of significant differences; finally, most cases of significant differences were noted in the distal supra-testicular artery (n = 12). Correlations were mainly seen for the end diastolic velocity, the peak systolic velocity and the blood volume (each with two semen evaluation parameters). The distal supra-testicular and the marginal artery at the cranial pole of the testis are recommended as the most appropriate segments of the vessel for performing a Doppler examination in the testicular artery due to the adequate size and the clear spectral waveforms as early as the 12th week of age of the animals.

Age-Related Differences in Testosterone Concentration and Its Relation to Testicular Biometrics, Hemodynamics, and Fertility in Alpacas (Vicugna pacos)

The goal of this study was to investigate the age-related differences in testosterone concentration and its relation to testicular biometrics, testicular blood flow, and fertility in alpacas (Vicugna pacos). Fifteen alpaca males with different ages (young (YM; ~12-14 mo.), n = 5; intermediate (IM; ~24 mo.), n = 5; and old (OM; ≥36 mo.), n = 5) were enrolled in the study. Blood samples were taken from each alpaca male and the circulating plasmatic testosterone concentration (TC; ng/mL) was determined using ELISA analysis. The testicular traits related to bio-morphometric parameters (the length (L), width (W), area (A), and volume (TV)) were assessed using B-mode ultrasonography. Pulse-wave/power Doppler ultrasonography was used to obtain the circulatory dynamic values (testicular hemodynamics) before the beginning of natural service mating. Significant differences were observed in TC among the age groups, increasing as the age of the males increased (2.47 ± 0.31, 8.45 ± 1.53, and 22.66 ± 2.15 for YM, IM, and OM, respectively; p < 0.05); however, no differences were observed regarding the testicular B-mode ultrasonographic parameters (L, W, and A) (p > 0.05). Positive correlations were observed between TV and testicular L, W, and A (r = 0.96, r = 0.95, and r = 0.96, respectively; p ≤ 0.001). Pulse-wave-Doppler-derived parameters such as the pulsatility index (PI) and the resistive index (RI), as well as the total vascularity area (TVA) assessed by power Doppler, were similar in all of the age groups studied (p > 0.05). General linear model (GLM) analysis showed a relationship between TC and TV (OR = 0.95; p = 0.04), as well as between TC and TVA (OR = 0.99; p= 0.02). Finally, no differences were observed regarding the pregnancy rate among the different age groups (p > 0.05). In conclusion, TC increased as the age of the alpaca males increased. Although TC was related to TV and TVA, the pregnancy rates obtained from individuals belonging to the different age groups were similar, indicating that TC, TV, and TVA were not determining factors in assessing the potential age-related fertility differences in alpaca males.

Seasonal Alterations in Testicular Hemodynamics and Echotexture in Relation to Semen Quality in Buffalo Bulls

The present study is aimed at investigating the usefulness of the pulsed-wave Doppler ultrasonography for the characterization of testicular blood flow in buffaloes during the nonbreeding and breeding seasons. Ten Egyptian buffalo bulls were evaluated for changes in the blood flow (Doppler’s indices: resistive index (RI) and pulsatility index (PI)) at the levels of supratesticular (STA) during the breeding (winter) and nonbreeding season (summer). The alterations in testicular parenchyma echotexture (pixel intensity (PIX) and echotexture heterogeneity (EH)) were assessed by computer analysis software. Circulating testosterone and nitric oxide (NO) concentrations and total antioxidant capacity (TAC) were measured colorimetrically. Sperm parameters including total and progressive motility %, viability %, morphology %, and concentrations were assessed. Results revealed lower values ( $p<0.05$ ) of RI ( $0.55\pm 0.02$ ) and PI ( $0.82\pm 0.03$ ) within the STA in the breeding period compared to the nonbreeding period (RI: $0.67\pm 0.03$ ; PI: $0.99\pm 0.01$ ). Higher ( $p<0.05$ ) PIX and EH were found in the nonbreeding season (PIX: $72.09\pm 1.81$ ; EH: $14.99\pm 1.37$ ) compared to the breeding season (PIX: $60.95\pm 1.51$ ; EH: $11.75\pm 0.63$ ). Concentrations of testosterone and TAC were not significantly changed. However, the concentrations of NO were greater ( $p<0.05$ ) during the breeding season ( $78.21\pm 0.87$ ) compared to those of the nonbreeding one ( $59.74\pm 2.97$ ). Total motility %, progressive motility %, viability %, and sperm concentrations were higher during the breeding season compared to that during the nonbreeding season ( $p<0.05$ ). In conclusion, seasonality alters testicular hemodynamics and echotexture, NO concentrations, and sperm quality in buffaloes without alterations in the testosterone and TAC levels.

Intramuscular administration of l-arginine boosts testicular hemodynamics, plasma concentrations of testosterone and nitric oxide in heat-stressed rams

The current study aimed to assess, for the first time, the effects of intramuscular injection of l-arginine (L-arg) on testicular hemodynamics, echogenicity, and plasma concentrations of testosterone, total antioxidant capacity, and nitric oxide (NO) in Ossimi rams. Twelve sexually matured heat-stressed rams were randomly assigned to one of two groups: the L-arg group (n = 6) received 5 mg/kg L-arg dissolved in 2 ml normal saline 0.9%, or the control group (n = 6) received merely 2 ml of normal saline 0.9%. Blood sampling, B-mode ultrasound assessment of the testicular parenchyma, and pulsed-wave Doppler ultrasound of the testicular artery for both right and left testis were performed immediately before 0 min and 1, 4, 24, 48, 72, and 168 h after L-arg or saline administration. In the L-arg group, resistive index (RI) and pulsatility index (PI) means were significantly lower compared to the control group at 4-168 h post-treatment. Plasma testosterone concentrations were higher (P < 0.05) at 4 h and onward in the L-arg treated compared to the control rams, the same for NO levels however its increase (P < 0.05) was observed as soon as 1 h post-treatment. In L-arg treated rams, NO concentrations were positively correlated to plasma testosterone concentrations (r = 0.7, p < .01), but negatively correlated to both RI and PI (r = -0.8 and -0.6, respectively, p < .01). In conclusion, l-arginine administration enhanced testicular blood flow and increased plasma testosterone and nitric oxide concentrations in heat-stressed rams.

Effects of a single dose of long-acting FSH on testicular blood flow, testicular echotexture, and circulating testosterone, estradiol, and nitric oxide in rams during the non-breeding season

The present study investigated the effect of a single administration of long-acting follicle simulation hormone (FSH) on testicular blood perfusion as measured by pulsed-wave Doppler ultrasonography, testicular echotexture, and circulating testosterone (T), estradiol (E2), and nitric oxide (NO) in the plasma of rams in the non-breeding season. Twelve Ossimi rams were subjected to either a single administration of long-acting FSH subcutaneously (FSH group; n = 6) or the vehicle (control group; n = 6). Assessment of testicular hemodynamics at the level of the supratesticular artery was performed just before administration (0 h), and at 4, 24, 48, 72, 96, and 168 h after FSH or the vehicle administrations. Testicular volume (TV), and echotexture of testicular parenchyma including pixel intensity and heterogeneity were derived by the computer analysis software. Concentrations of T, E2, and NO were measured using commercial kits. Results revealed significant decreases (P ˂ 0.05) in the values of Doppler indices (resistive index: RI and pulsatility index: PI), especially at 48 h after administration of FSH (RI: 0.42 ± 0.02, PI: 0.56 ± 0.04) compared to their values in the control group (RI: 0.54 ± 0.03, PI: 0.77 ± 0.04). FSH administration induced significant decreases (P ˂ 0.05) in the pixel intensity of testicular parenchyma. Testicular volume and T concentrations were not significantly changed (P ˃ 0.05). Concentrations of E2 increased significantly (P ˂ 0.05) at 48 h and 72 h after FSH administration. (30.07 ± 5.23 pg/ml, 29.93 ± 1.44 pg/ml, respectively) compared to their values before FSH administration (14.63 ± 1.37 pg/ml). Concentrations of NO increased significantly (P ˂ 0.05) in the FSH group between 4 h to 48 h compared to the values in the control one. In conclusion, a single administration of long-acting FSH enhanced testicular blood perfusion as measured by pulsed Doppler ultrasonography in rams during the non-breeding season. Concurrently, significant increases in the concentrations of E2 and NO were found.

The Use of Doppler Ultrasonography in the Examination of Testicles in Dogs

Doppler ultrasonography is method suitable for observing and measuring the blood supply of many organs. Its principle is the change in the frequency of wave blood that moves with respect to the source of the wave (probe). In a testicular examination, the use of Doppler can also be very useful for detecting abnormalities or pathological conditions. The aim is just to characterize the flow in arteria testicularis in clinically healthy dogs aged 1-5 years. Twelve dogs were included in the study, of which 6 were rough collies weighing approximately 23 kg and 6 were standard dachshunds weighing approximately 9 kg. The pulsatility index (PI) and resistance index (RI) of a.testicularis, as well as the dimensions of the testicles - height and depth, were assessed by ultrasonographic examination using the ALOKA ProSound Alpha 6 ultrasonographic device (Hitachi-Aloka, Japan). The statistical evaluation of the results shows that the differences between the averages of both measurements of PI and RI indices are highly significant, so the weight of the individual had a high effect on the measured values of PI and RI indices. The depth of the testicles was also directly related to the increasing values of PI and RI indices and to the weight of the dogs, in contrast to their height, which did not show any statistical significance in this respect. The measured values and findings may in the future also serve as a basis for determining reference values in testicular ultrasonography according to the weight of dogs, which may be beneficial in clinical status assessment, diagnosis of various pathological conditions, or predicting spermatogenesis and fertility of the individuals.

Application of ultrasound technique to evaluate the testicular function and its correlation to the sperm quality after different collection frequency in rams

The frequency of semen collection is a crucial factor to consider in the rams performance inside breeding centers workout. To evaluate this factor, ram Breeding Soundness Evaluation could include sperm quality evaluation and new predictive and non-invasive tools such as ultrasound technique. In this work, an advanced ultrasonography technology, analyzing the testicular volume, echotexture, and vascular function, was used in three different frequencies of semen collection (abstinence frequency, AF; standard frequency, SF; and intensive frequency, IF). Semen samples were cooled (15°C, 6 h) and evaluated in terms of production, motility, viability, apoptosis, and content of reactive oxygen species. Correlation coefficients were calculated between ultrasonography measurements of echotexture and blood flow and sperm quality parameters. Our results showed an increase in the testicular echotexture when the frequency of semen collection was intensified. Doppler parameters (PSV, RI, PI, TABF) increased (P ≤ 0.05) when the frequency of semen collection was intensified. The sperm motility and functionality decreased in the samples of IF (P ≤ 0.05), evidencing the frequency of semen collection's influence. Moreover, moderate positive correlations were established among echotexture and different Doppler parameters with motility parameters in SF. Furthermore, the influence of abstinence days on AI success was analyzed in a field assay. The highest fertility rates were obtained when males had two to five abstinence days. To conclude, frequency of semen collection could be influenced in terms of semen quantity and sperm quality, showing changes in parenchyma echotexture and testicular vascularization. The standard semen collection frequency was the most adequate option. In addition, ultrasonography may be a predictive tool for estimating variations in the sperm quality of donor rams subjected to different frequencies of semen collection in reproduction centers.

An updated insight on testicular hemodynamics: Environmental, physiological, and technical perspectives in farm and companion animals

In all organs, control of blood flow is important but might be particularly critical for testicular functions. This is because of the very low oxygen concentration and high metabolic rate of the seminiferous tubules, the physiological temperature of the testis, and its location outside the abdominal cavity. Many factors affect the characteristics of TBF in farm and companion animals, such as environment (thermal and seasonal effects) and physiological (species, breeds, age, body weight, and sexual maturity). Thermal environment stress has detrimental effects on spermatogenesis and consequently has more serious impacts on both human and animal fertility. Numerous studies have been performed to assess TBF in different animal species including bulls, rams, bucks, alpacas, stallions, and dogs with varied results. Hence, assessment of TBF by Doppler ultrasonography is of great importance to estimate the effect of high environment temperature on testicular functions. Also, differences observed in the TBF may result from different technical aspects such as the identification of the segment of the testicular artery to be examined. In the current review, we focused on the imperative roles of TBF in various animal species. Besides, we discussed in detail various factors that could affect TBF. These factors can significantly modify the TBF and thus should be considered when establishing reference values in farm animals for better clinical diagnosis. The information provided in this review is valuable for researchers and veterinarians to help them a better understanding of testicular hemodynamics for the proper evaluation of breeding soundness examination in males.

Single melatonin injection enhances the testicular artery hemodynamic, reproductive hormones, and semen parameters in German shepherd dogs

This study aimed to determine the effects of melatonin administration on testicular vascular perfusion in relation to steroid hormones and semen characteristics in dogs. The study included 12 normospermic German shepherd dogs (weighed 35 ± 0.5 kg and aged 4 ± 0.5 years). Males received a single melatonin administration (melatonin dimethyl sulfoxide + corn oil via subcutaneous route; MEL; n = 6), while the rest of the animals served as controls (dimethyl sulfoxide + corn oil; Control; n = 6). Males were subjected to routine examination on days -15, 0, 15, 30, 45, and 60. All examined dogs were subjected to Doppler screening, semen collection, and blood sampling. The MEL group showed a significant (P < 0.05) elevation in semen volume, concentration, percentage of sperm motility, and total sperm × 106 / ejaculate compared to other control males. Doppler indices as resistance (RI) and pulsatility (PI) indices declined (P < 0.05) from D 30 (1.02 ± 0.01) until day 60 (0.87 ± 0.02) of treatment. In MEL males, the peak systolic point of velocity (PSV; cm/sec) of the testicular artery elevated (P < 0.05) on day 60 (20.15 ± 0.99) compared to its value on day 0 (17.39 ± 1.84). On D 60, the levels of testosterone (T), estradiol 17-ß (E2), and nitric oxide (NO) elevated (P < 0.05). A negative correlation was detected between testicular volume, scrotal circumference (SC), T levels, Doppler indices, and velocities. In conclusion, single melatonin administration could improve testicular vascularization via increasing Doppler velocities and intratesticular colored areas. In addition, it could improve semen picture and steroids (T and E2) and nitric oxide.

Advances in the ultrasound diagnosis in equine reproductive medicine: New approaches

Ultrasound technology has led to new lines of research in equine reproduction, and it has helped to greatly improve clinical diagnosis and reproductive outcomes in equine practice. This review aims to discuss the potential clinical uses and new approaches of ultrasonography in equine reproduction. Doppler modalities are usually used to evaluate the vascularization of the follicles, corpus luteum (CL), and the uterus in the mare for diagnostic purposes. Inclusion of Doppler ultrasound in artificial insemination and embryo transfer programs could improve the reproductive outcome of these techniques. Better selection of recipients based on CL functionality, early pregnancy diagnosis 7-8 days postovulation of the donor before flushing or diagnosis of mares with endometritis with pathological increases of blood flow are examples of clinical applications in the mare. In the stallion, colour Doppler ultrasound has improved the diagnostic potential of B-mode ultrasound, improving the differential diagnosis of pathologies such as testicular torsion (decrease or absence of blood flow in the cord) and orchitis (increased blood flow in the cord). The incorporation of pulsed Doppler ultrasound into the reproductive evaluation of the stallion has enabled early identification of stallions with testicular dysfunction, thus allowing administration of timely treatment and subsequent improvements of the fertility prognosis for these animals. In addition, this technique has been used in the monitoring of patients undergoing medical and surgical treatments, thus verifying their efficacy. Recently, computer-assisted pixel analysis using specific software has been performed in research work in order to semi-quantitatively evaluate the vascularization (colour and power Doppler) and echotexture of different organs. These softwares are now being developed for clinical purposes, as is the case with Ecotext, a computer program developed for the evaluation of testicular echotexture, providing information on testicular functionality.

Testicular haemodynamics, plasma testosterone and oestradiol concentrations, and serum nitric oxide levels in the Egyptian buffalo bull after a single administration of human chorionic gonadotropin

This current study aimed for the first time to evaluate the effect of a single intravenous administration of human chorionic gonadotropin hormone (hCG) on the testicular artery haemodynamics measurements (resistance [RI], and pulsatility indices [PI]), plasma steroids (estradiol-17β and testosterone) and nitric oxide (NO) levels in buffalo bulls. Twelve Egyptian buffalo bulls weighted 450 ± 20 kg were randomly divided into the hCG group (n = 6) and injected a single dose with Ovogest (EPIFASI; 5,000 IU, iv), whereas the others (n = 6) were injected with normal saline and served as controls. Doppler evaluation and blood sampling were performed just before the administration (hour 0) and at 1, 2, 4, 6, 8, 10, 24 and 28 hr after administration. Bulls in the control group did not show any alterations in hormonal levels and blood flow parameters (p > .05). In the hCG group, RI was declined (p < .05) in 6 hr post-administration (0.31 ± 0.01 versus 0.45 ± 0.01), while PI was declined (p < .05) later in 10 hr (0.74 ± 0.01 versus 1.23 ± 0.02). Additionally, testicular blood flow was increased (p < .05) 8 hr (42.02 ± 1.02 ml/min/100 g versus 31.34 ± 0.88 ml/min/100 g) after administration. Testosterone and NO levels were (p < .05) increased at 4 and 6 hr post-administration (3.55 ± 0.03 ng/ml versus 2.84 ± 0.01 ng/ml, and 55.32 ± 4.25 µmol/L versus 32.21 ± 1.55 µmol/L), whereas oestradiol levels were elevated (p < .05) in 6 hr (31.25 ± 0.08 pg/ml) only post-administration then declined. In conclusion, the single intravenous administration of hCG triggered many alterations in the supratesticular artery vascularization and hormonal profile that could affect positively on steroidogenesis and testicular function in buffalo bull.

Morphological and ultrasonographic characterization of the three zones of supratesticular region of testicular artery in Assaf rams

To fully understand the histological, morphometrical and heamodynamic variations of different supratesticular artery regions, 20 mature and healthy Assaf rams were examined through ultrasound and morphological studies. The testicular artery images of the spermatic cord as shown by B-mode analysis indicated a tortuous pattern along its course toward the testis, although it tends to be less tortuous close to the inguinal ring. Doppler velocimetric values showed a progressive decline in flow velocity, in addition to pulsatility and vessel resistivity when entering the testis, where there were significant differences in the Doppler indices and velocities among the different regions. The peak systolic velocity, pulsatility index and resistive index were higher in the proximal supratesticular artery region, followed by middle and distal ones, while the end diastolic velocity was higher in the distal supratesticular region. The total arterial blood flow and total arterial blood flow rate reported a progressive and significant increase along the testicular cord until entering the testis. Histological examination revealed presence of vasa vasorum in the tunica adventitia, with their diameter is higher in the proximal supratesticular zone than middle and distal ones. Morphometrically, the thickness of the supratesticular artery wall showed a significant decline downward toward the testis; meanwhile, the outer arterial diameter and inner luminal diameter displayed a significant increase distally. The expression of alpha smooth muscle actin and vimentin was higher in the tunica media of the proximal supratesticular artery zone than in middle and distal ones.

The Relationship between the Testicular Blood Flow and the Semen Parameters of Rams during the Selected Periods of the Breeding and Non-Breeding Seasons

The study aimed to conduct advanced semen evaluation tests during routine ram examination periods in the breeding and non-breeding seasons and to investigate their correlation with the dynamics of testicular blood flow. Semen was collected from eighteen rams, and pulse wave Doppler examination before (BBS), during (BS), and after the breeding season (ABS). Routine and advanced semen analysis, including computer-assisted sperm analysis (CASA), sperm chromatin dispersion test (SCD), and motile sperm organelle morphology examination (MSOME), were conducted. In Doppler ultrasonography, the peak systolic velocity (PSV), end-diastolic velocity (EDV), resistive index (RI), and pulsatility index (PI) were calculated. In BS period, high sperm concentration (p < 0.0001) and total sperm number/ejaculate (p = 0.008) were noted. During the BBS period, a low percentage of forwarding motility (p = 0.017) and high sperm abnormalities (p = 0.005) were found. Also during this period, both SCD and MSOME revealed high sperm DNA fragmentation (p < 0.0001) and signs of vacuolization (Grade II-IV, p < 0.05). The advanced features of higher sperm abnormalities (Grade IV of MSOME) correlated with an increase RI (ρє <0.60;0.61>) and PI (ρє <0.46;0.52>), whereas the basic percentage of sperm abnormalities correlated with the EDV (ρє <0.44;0.73>) value. One may conclude that the current preliminary study requires further research concerning the monthly examination of a ram to provide full yearly characteristics of the relation between advanced semen evaluation tests and the dynamics of testicular blood flow.

Testicular Ultrasound Analysis as a Predictive Tool of Ram Sperm Quality

Simple Summary

In animal production, the prediction of male fertility is vital for the success of specific techniques such as artificial insemination. Thus, testicular ultrasound, a non-invasive diagnostic procedure, could be a useful tool. Moreover, recent ultrasound-video analysis and software developments allow the visualization of tissue at the microscopic level. The objective of this work was to establish a possible correlation between testicular ultrasonography and semen quality in rams. For this purpose, the testicles of nine rams were evaluated and the semen was analyzed for one year. The results revealed that the number of white and grey pixels correlated with sperm parameters indicating poor seminal quality. On the other hand, the increase in the seminiferous-tubule density or the lumen area of these tubules was related to a rise in seminal quality. Therefore, ultrasound-video analysis could be a good tool for evaluating the fertility of rams, either for artificial insemination or on the farm.

Abstract

Testicular ultrasound is a non-invasive technique that could be very useful for predicting ram seminal quality. Recent software developments allow macroscopic and microscopic evaluation of testicular parenchyma. Thus, the aim of this study was to evaluate the testicular echotexture using ultrasound-video analysis and investigate its possible correlation with semen quality. Nine rams were evaluated for one year using a portable ultrasound scanner and the echotexture was analyzed with ECOTEXT^® software. The number of black (Ec1), white (Ec2), and grey pixels (Ec3), tubular density (TD), lumen area (LA), and lumen diameter (LD) were analyzed. Semen was collected by an artificial vagina the same day and the sperm concentration, morphology, motility, viability, phosphatidylserine (PS) translocation, reactive-oxygen-species (ROS) levels, DNA damage and capacitation state were evaluated. Ec2 and Ec3 correlated positively with “bad quality” sperm parameters (the percentage of spermatozoa with high ROS levels, with PS translocation and proximal cytoplasmic droplets), and negatively with motility. In contrast, TD and LA showed a positive correlation with “good quality” parameters (motility or normal morphology) and a negative correlation with spermatozoa with high ROS levels, with DNA fragmentation, and proximal or distal cytoplasmic droplets. Thus, echotexture analysis by ultrasound-video analysis could be a valuable tool for assessing ram fertility.

Trends in Small Animal Reproduction: A Bibliometric Analysis of the Literature

Simple Summary

Reproduction in small animals is an expanding research area, with focus on breeding improvement and clinical management of domestic carnivores. The aim of the present study was to conduct a bibliometric analysis of the literature of the last decade on small animal reproduction, to point out main sources, most prolific countries, and emerging and neglected topics. Results show that research in biotechnologies for assisted reproduction has a central and increasing role in this field. Diversity in author keywords was also pointed out and a consensus to better categorize research in this field is proposed to reduce this problem in the future.

Abstract

Small animal reproduction (SAR) is a main research field in veterinary medicine and bibliometric analyses are useful to investigate trends in specific research areas. The objective of the present study was to conduct a bibliometric analysis of the literature of the last decade on SAR. A search equation was created, and documents were retrieved from the Web of Science database. Documents were manually revised, categorized and R software version 4.1.2 with Bibliometrix R package version 3.1 and MS Excel were used to perform the analyses. The included documents (n = 1470) were mainly research articles (78%). The top countries for the number of documents and citations were Brazil, United States, Italy, Poland, and Korea. These also account for the most prolific authors and institutions. Analyses by author keywords, categories, and recent reviews of the literature suggest that research on the canine species is more abundant than research on the feline one and that reproductive biotechnologies are a main research focus. Some clinical topics are still considered niche or neglected themes (e.g., semen collection in tomcats, neonatology). However, heterogeneity and ambiguity in keywords and categories are undeniable. This study offers interesting insights, providing definitions for main keywords in the field of SAR.

Ageing affects plasma steroid concentrations and testicular volume, echotexture and haemodynamics in rams

The objective was to determine the effect of ageing on plasma steroid concentrations and testicular volume, echotexture and haemodynamics in Ossimi rams. Twenty-four rams were allocated, by age, into three groups: young (1 year; 32.00 ± 0.78 kg, n = 6); mature (2.5 years; 48.00 ± 1.02 kg, n = 9) and aged (7.5 years; 65.00 ± 1.10 kg, n = 9). Aged rams had the highest (p ˂ 0.05) plasma testosterone concentrations 3.90 ± 0.75 ng/ml (three-fold the other groups), whereas in young rams, plasma estradiol-17β concentrations (5.85 ± 0.34 pg/ml) were approximately one-quarter (p ˂ 0.05) of other groups. Regarding pulsed-wave Doppler indices values of the (resistive index RI; and pulsatility index PI) were lower (p ˂ 0.05) in the mature (0.32 ± 0.04 and 0.36 ± 0.03, respectively) and aged (0.51 ± 0.03 and 0.77 ± 0.06) rams compared to young rams (0.62 ± 0.03 and 0.98 ± 0.07). In the young group, testicular pixel intensity was highest (p ˂ 0.05) but values of coloured area/pixels were lowest (p ˂ 0.05) compared to the other groups. In conclusion, these parameters indicate that aged rams (7.5 years) are likely to be suitable for breeding ahead of the younger aged groups (1 and 2.5 years) examined, but a final decision would need to be tempered by consideration of other parameters in the breeding soundness examination (BSE), such as physical soundness and semen characteristics. Of the parameters studied, testicular pixel intensity could be most readily incorporated in a BSE for deciding a ram's breeding efficiency.

Effects of buserelin administration on testicular blood flow and plasma concentrations of testosterone and estradiol-17β in rams

This research aimed to examine for the first time the impact of single dose administration of gonadotropin-releasing hormone (GnRH) analog buserelin acetate on the testicular blood flow measurements (peak systolic velocity [PSV], end-diastolic systolic velocity [EDV], resistive index [RI], and pulsatility index [PI]) and the plasma steroids (testosterone and estradiol-17β) concentrations in rams. For this purpose, twelve adult Ossimi rams were randomly assigned into the buserelin group (n = 8) and were injected intravenously (iv) with buserelin acetate (0.008 mg/ram), whereas the remaining rams (n = 4) were injected with normal saline iv and served as a control group. Blood sampling and testicular pulsed-wave Doppler scanning were conducted immediately before (0) and 1, 3, 6, 24, 48, 72, 120, and 168 h after treatment. The control group did not reveal any substantial changes (P > 0.05) in the examined parameters, except for the EDV (P < 0.05). In the buserelin-treated group, a marked reduction in RI and PI values (P < 0.05) occurred 1 to 3 h after administration of buserelin. Besides, there was a significant increase in testosterone plasma concentrations following buserelin treatment. In conclusion, the administration of buserelin triggered a series of substantial changes in the testicular blood perfusion and steroidogenesis that could have a positive effect on testicular function in rams.

Melatonin improves testicular haemodynamics, echotexture and testosterone production in Ossimi rams during the breeding season

The objective was to determine effects of a single parenteral dose of melatonin on testicular blood flow indices, testicular echogenicity and plasma testosterone concentrations in rams during the physiological breeding season. We hypothesized that melatonin enhances testicular blood flow, echogenicity and plasma testosterone concentrations during the breeding season in rams. During the breeding season, 12 sexually mature Ossimi rams were randomly allocated to either a melatonin group (n = 8) that received 18 mg of melatonin in 1 ml of corn oil (injected SC) or a control group (n = 4) that received 1 ml corn oil only. Blood collection and ultrasonographic assessment of the testes and supratesticular arteries were conducted immediately before treatment (W0) and once weekly for 6 weeks after melatonin injection (W1-W6). Mean plasma testosterone concentrations were greater (p < .05; at least 1 ng/ml) in the melatonin-treated group compared to the control group from W4 to W6 after treatment. A decrease (p < .05) in both resistive index (RI) and pulsatility index (PI) began 1 week after melatonin injection (W1) and persisted until the end of the experiment, with mean RI and PI values in the melatonin group lower (p < .05) than those in the control group on W3 and W4. Furthermore, plasma testosterone concentrations in melatonin-treated rams were inversely correlated to both RI and PI (r = -.7 and -.6, respectively, p < .01). Testicular echogenicity decreased (p < .05) 1 week after melatonin injection (W1) and remained lower (p < .05) in the melatonin-treated group compared to the control group until the end of the study (W6). In conclusion, melatonin administration significantly altered testicular blood flow and echogenicity and increased plasma testosterone concentrations in Ossimi rams during the breeding season.

Exogenous oxytocin administration improves the testicular blood flow in rams

The current research aimed to examine the effects of single-dose oxytocin administration on testicular blood flow measurements peak systolic velocity (PSV), end-diastolic velocity (EDV), resistive index (RI) and pulsatility index (PI) and plasma steroid (testosterone and oestradiol-17β) concentrations in rams. In the treated group, eight mature Ossimi rams during the breeding season were injected intravenously (iv) with 20 IU oxytocin, while the other eight male rams were administered normal saline (2 ml) iv as a control group. Venous blood samples and testicular blood flow in the left and right testes were examined immediately before (0) and 5, 30, 60 and 120 min after injections. The control group did not show significant changes in the variables examined (p > .05), except for the EDV (p < .05). In the treated group, the administration of oxytocin led to a significant decrease in RI and PI values starting 5 min after oxytocin administration until 60 min after its application (p < .05). The plasma concentrations of testosterone and oestradiol-17β raised from 5 to 30 min after oxytocin injection (p > .05) and then declined significantly until 120 min (p < .05). In conclusion, oxytocin is a potent testicular vasodilator affecting the testicular vascular tone and steroid concentrations in rams.

Ageing changes testes and epididymis blood flow without altering biometry and echodensity in dogs

Senescence leads to deleterious effects in testicular function, sperm quality and fertility in dogs. There, however, are no consistent results of vascular changes in the testes and epididymis during natural ageing in dogs. The aim of this study, therefore, was to compare testes and epididymis blood flow, biometry and echodensity between young and senile dogs. Ten young dogs (1-4 years) and eight senile dogs (over 7 years) were selected and assigned to two experimental groups: Young Group and Senile Group. Dogs were evaluated using testicular and epididymis B-mode (dimensions and echodensity) and Doppler ultrasonography (tissue perfusion parameters and blood flow velocity of the testicular artery). There were no differences between experimental groups for the echographic evaluation of testicular and epididymis parenchyma and biometric variables. The dogs in the Young Group had greater (P = 0.02) testes vascularization score and greater (P = 0.06) testicular artery blood flow velocity than those in the Senile Group. Furthermore, the older dogs had a greater (P = 0.06) pulsatility index of the testicular artery than those in the Young Group. Ageing, therefore, seems to cause natural hemodynamical changes to the testicular artery, resulting in reduced blood flow (ischemia) and tissue damage. Testes and epididymis vascular characteristics, therefore, may represent the causal factors for changes in spermatogenesis and, as a consequence, negatively affect the sperm quality of older dogs. In conclusion, senescence alters testicular artery blood flow and vascularization of the testes, without changing testicular and epididymis ultrasonographic dimensions and echodensity in dogs.

Assessment of the accuracy of testicular dysfunction detection in male donkey (Equus asinus) with the aid of colour-spectral Doppler in relation to plasma testosterone and serum nitric oxide levels

This study aimed to determine the usefulness of colour and pulsed Doppler modes for the accurate diagnosis of donkeys suffering from subfertility to determine whether testicular vascularity assessment could be an indicator for sperm functionality. The study sample was composed of 10 male donkeys with normospermia (control group) and 10 donkeys with hypospermia. Animals underwent scrotal circumference measurement, testicular Doppler examination, seminal evaluation, blood sampling and hormonal assay. Semen volume and concentration were significantly (p ≤ .05) lower in the subfertile group (30.25 ± 1.22 ml and 89.44 ± 2.55 × 10⁶ /ml) as compared with the control group (82.76 ± 1.65 ml and 452.78 ± 1.25 × 10⁶ /ml), and total sperm/ejaculation was significantly (p ≤ .05) higher in the normal donkeys (28.30 ± 2.32 × 10⁹ /total ejaculated) as compared with the subfertile group. Intratesticular coloured area showed a marked decline in the hypospermic males. There was no significant difference between the two groups in testosterone level, although the normal group showed an increase in nitric oxide metabolites. Both Doppler indices of the three branches of the testicular artery were elevated significantly (p ≤ .05) in abnormal donkeys, whereas Doppler peak systolic and end-diastolic velocities were increased in the normal group. Male donkeys with subfertility demonstrated lower arterial vascularity parameters in the form of intratesticular coloured area and blood flow rate; therefore, the most optimal parameters for differentiating subfertile hypospermic from normospermic donkeys were found to be the two Doppler indices, velocities parameters, testicular blood flow rate and nitric oxide levels.

New Approaches to Assess Fertility in Domestic Animals: Relationship between Arterial Blood Flow to the Testicles and Seminal Quality

The early identification of infertile males improves reproduction efficiency at a production level and is essential to secure high production rates. Before entering a breeding program, males must pass an initial breeding soundness examination (BSE) which consist of several diagnostic exams whose end point is to estimate their future fertility. There is ongoing research to find new markers that allow better identification of fertile males. Doppler mode allows the quantitative and qualitative evaluation of the irrigation of organs. When evaluating the reproductive system, Doppler mode has been successfully used for the evaluation of the uterine and ovarian irrigation. In males, it is gaining relevance for the evaluation of testicular irrigation. Researchers have found a relationship between pulsed-wave Doppler velocimetric parameters and seminal quality in various domestic animal species. This suggests Doppler ultrasound parameters should be considered as objective parameters to evaluate testicular function. In this review, we analyze the results in the main domestic animal species and discuss the differences and similarities among the results. We also discuss the effect of the location of the measurements, breed, season and laterality in the measurement of Doppler velocimetric parameters as well as the impact and limitations of this method of assessing breeding soundness.

Advances in applications of color Doppler ultrasonography in the andrological assessment of domestic animals: A review

Compared to human cases, potential applications of Doppler imaging technology in farm animals' practice are still limited and are mostly concerned with females. Testicular blood perfusion (TBP) is the pathway through which all nutrients, oxygen, and regulatory agents pass through to the testis. TBP is crucial to the testis function because of the high metabolic rate and very low concentration of oxygen in the seminiferous tubules, which constitute about 70%-80% of the testicular mass. Color Doppler ultrasonography is one of the recent non-invasive technologies, which plays a vital role in the assessment of blood flow to the testis in various animal species. In the past 20 years, a significant number of studies have highlighted the importance of assessments of TBP using color Doppler ultrasonography to illustrate its potential uses for breeding soundness examination, diagnosis, and monitoring of infertility problems in farm animals. This review was aimed at providing, for the first time, updated knowledge on the potential clinical uses of color Doppler ultrasonography for the assessment of TBP in domestic animals. Additionally, a few essential details on the relationship between TBP and male fertility are discussed in this review. Furthermore, a number of caveats relating to the use of color Doppler ultrasonography are discussed, which collectively appear to constrain its routine, on-farm application for breeding soundness assessments, at least at the present. The new perspectives related to animal reproduction that researchers claim to do in further investigations are also discussed.

Correlation of Prostatic Artery Blood Flow Assessed by Doppler Ultrasonography with Semen Characteristics in Beagle Dogs

Simple Summary

This study examined the blood flow parameters of the prostate artery before dog ejaculation assessed by pulsed-wave Doppler ultrasound (PwD) changes. The main objective of this study was to characterize the vascular parameters of the prostatic artery in beagle dogs and to explore the potential use of Doppler ultrasonography as a complementary method in dog stud selection. These findings report differences between blood flow parameters in cranial and caudal locations of the prostatic artery in comparison to subcapsular and parenchymal locations. There was a high positive correlation of peak systolic velocity with total volume and sperm concentration. In conclusion, estimation of the PwD parameters of the cranial prostatic artery may be useful in the breeding evaluation of dogs.

Abstract

Pulsed-wave Doppler ultrasonography (PwD) is a method used to rapidly and noninvasively assess blood flow dynamics of the canine prostate. Modifications in gland vascularization can affect seminal plasma production and consequently sperm quality. The aim of this study was to determine the normal blood flow parameters of the prostate artery in beagle dogs and to analyze the correlations between vascular flow and semen quality characteristics. PwD was performed on five beagle dogs (5–6 years) measuring vascular features in four different locations of the prostatic artery (cranial, subcapsular, parenchymal and caudal); the measured features were peak systolic velocity (PSV), end-diastolic velocity (EDV), resistive index (RI) and pulsatility index (PI). Ejaculates were obtained using digital manipulation and semen quality was evaluated by determining macroscopic (total volume, sperm-rich fraction volume, color and pH) and microscopic (sperm motility, morphology, viability and acrosome integrity) characteristics. The values of PSV, PI and RI in cranial and caudal prostatic arteries were significantly higher than in subcapsular and parenchymal arteries (p < 0.05). Moreover, a positive correlation of PSV value in the cranial region of the prostatic artery with total ejaculate volume (p < 0.01, r = 0.612) and sperm concentration (p < 0.01, r = 0.587) was determined. PI index was negatively correlated with sperm concentration (p < 0.01, r = −0.709). In conclusion, the results suggest that the prostatic artery blood flow parameters can affect macroscopic semen quality characteristics in healthy dogs.

Pulse-wave Doppler pulsatility and resistive indexes of the testicular artery increase in canine testis with abnormal spermatogenesis

Pulse-wave Doppler (PWD) ultrasonography of the testicular artery was recently used to compare parameters in fertile and infertile males, or males with normal and abnormal semen quality, while no studies verified the concomitant histological feature of the testis. The experimental hypothesis of the present study was that the blood flow parameters measured by PWD at different levels of the testicular artery reflect sperm attributes evaluated on spermatozoa collected from the tail of the epididymis and testicular histological characteristics. Pulse-wave Doppler parameters were recorded on both testes from 16 dogs of unknown fertility. After routine castration, epididymal spermatozoa were collected and evaluated for sperm total and progressive motility, membrane integrity, and sperm morphology. Testes were submitted to histological and immunohistochemical evaluations to quantify microscopic attributes and connective tissue and vascular area extent, respectively. The findings showed that the increased PWD indexes were suggestive of testicular histological alteration since negative correlations were found between pulsatility index and resistive index, measured in the marginal testicular artery, and histological attributes such as the seminiferous epithelial thickness (R = -0.528, P = 0.016 and R = -0.554, P = 0.005, respectively) and the tubular area/total area ratio (R = -0.494, P = 0.024 and R = -0.563, P = 0.004, respectively). Some histological characteristics, such as tubular diameter, seminiferous epithelium thickness, and the tubular area/total area ratio of the testis are correlated with the percentage of primary abnormalities (R = -0.874, P = 0.001, and R = -0.847, P = 0.001, and R = - 0.865, P = 0.001, respectively). In testes with increased sperm primary abnormalities, higher pulsatility index was found compared with testes with normal spermatogenesis in supratesticular artery (1.07 ± 0.06 vs 0.82 ± 0.23, P < 0.05), marginal artery (0.73 ± 0.04 vs 0.61 ± 0.07, P < 0.05), and intratesticular artery (0.67 ± 0.03 vs 0.43 ± 0.1, P < 0.05). Similarly, the resistive index was found significantly higher in the same vessel tracts in testes with abnormal and normal spermatogenesis (0.62 ± 0.02, 0.53 ± 0.02, and 0.46 ± 0.02 vs 0.51 ± 0.06, 0.44 ± 0.04, and 0.32 ± 0.06, respectively; P < 0.05). Our data demonstrated for the first time the relationship between PWD indexes and the contextual testicular architecture, suggesting that the pulsatility and resistive indexes could be an effective tool in andrology. In light of different histological alterations in the testis, caution is warranted in the definition of thresholds for normal and abnormal testicular blood flow indexes.

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.

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

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.

Correlation of testicular artery Doppler velocimetry with kinetics and morphologic characteristics of epididymal sperm in dogs

Sperm quality can be affected by a reduction in testicular blood flow, which can be measured by Doppler ultrasonography. The aim of this study was to correlate the Doppler velocimetry of the testicular artery with kinetics of the epididymal spermatozoa in dogs. Twenty-two dogs (44 testicles) were evaluated by Doppler ultrasonography in five regions of the testicular artery before orchiectomy. Spermatozoa were recovered by the epididymal tail compression technique and analysed for kinetics on a computer-assisted semen analysis (CASA system). Morphology (modified Karras) and sperm membrane integrity were analysed by eosin-nigrosine staining. Data were analysed by Pearson's correlation test (p < .01). The mean total motility was 69.0% ± 17.7, progressive motility was 43.7% ± 14.7, average path velocity (VAP) was 127.0 µm/s ± 20.7, curvilinear velocity (VCL) was 221.0 µm/s ± 31.1, and sperm velocity index (SVI) was 389.9 ± 56.1. There were positive correlations between the peak systolic velocity (PSV) in the proximal supratesticular region with the SVI (r = .529), VCL (r = .555) and VAP (r = .473), and a negative correlation with the percentage of slow spermatozoa (r = -.463). The results suggest that the testicular artery blood flow velocity can positively affect the speed of spermatozoa movement. For the first time, we have correlated sperm kinetics with the Doppler evaluation of the testicular artery in dogs.

Imaging of the male reproductive tract: Not so easy as it looks like

Diagnostic imaging is one of the most important tools in the breeding soundness evaluation of dogs and cats with reproduction problems. In recent years several imaging techniques have been developed, trying to aid the diagnosis and to differentiate between abnormal findings. This review presents the current knowledge on the imaging of normal and abnormal testes, spermatic cord, excurrent duct system, scrotum, accessory sex glands, penis and muscles for protrusion, erection and ejaculation of the dog and of cat. It also highlights the weak points and disadvantages of each imaging technique.

Passive immunization against inhibin increases testicular blood flow in male goats

The present study investigated whether or not passive immunization against inhibin modulates testicular blood flow in goats. Male Shiba goats were injected with either 10 ml of inhibin antiserum (INH group; n = 5) or 10 ml of normal castrated goat serum (NGS group; n = 4). Concentrations of FSH, LH, testosterone (T), and estradiol (E2) in the plasma were measured by radioimmunoassay. Blood flow within the supratesticular (STA) and marginal testicular arteries (MTA) were measured by color pulsed-Doppler ultrasonography, and Doppler indices (resistive index; RI and pulsatility index; PI) were recorded. Results revealed significant increases in concentrations of FSH and E2 in the INH group compared to those in the NGS group (P < 0.05). Animals in the INH group had greater (P < 0.05) FSH concentrations than those in the NGS group in the period between 60 h and 144 h after treatment than at any other time. Estradiol concentrations were greater (P < 0.05) in the INH group than in the NGS group at 6 h (12.15 ± 2.09 pg/ml vs 5.49 ± 1.17 pg/mL), 12 h (8.27 ± 1.29 pg/mL vs 3.05 ± 0.38 pg/mL), and 36 h (9.35 ± 1.31 pg/mL vs 5.09 ± 0.46 pg/mL) after treatment than at any other time. Concentrations of LH and T did not significantly change between the two groups. Goats in the INH group had lesser (P < 0.05) RI of the STA than those in the NGS group and RI values were lesser at 24 h (0.37 ± 0.031 vs 0.49 ± 0.004) and 120 h (0.38 ± 0.028 vs 0.55 ± 0.048) after treatment than at any other time. Furthermore, values of RI and PI of the MTA were significantly lesser (P < 0.05) in the INH group compared to those in the control group at 48 h (RI of MTA: 0.21 ± 0.014 vs 0.37 ± 0.039; PI of MTA: 0.24 ± 0.016 vs 0.46 ± 0.058) after treatment than at any other time. In conclusion, passive immunization against inhibin has a stimulatory effect on testicular blood flow in goats by inducing decreases in the RI values of the STA and MTA.

Administration of melatonin improves testicular blood flow, circulating hormones, and semen quality in Shiba goats

Despite the role of melatonin in the regulation of the sleep-wake cycle and seasonal-reproduction, the present study investigated, for the first time, the potential role of melatonin on testicular blood flow (TBF) in goats. Twelve sexually mature male Shiba goats were exposed to a single s.c. injection of either melatonin suspended in one ml of corn oil (melatonin group; 36 mg/goat; n = 5) or one ml of corn oil (control group; n = 7). Monitoring the changes in TBF was done one week before (W-1), at the time of injection (W0), and once a week for 8 weeks after injection using color-pulsed Doppler ultrasonography. Concentrations of FSH, LH, inhibin, testosterone (T), estradiol (E2), and insulin-like growth factor-1 (IGF-1) in plasma were determined by radioimmunoassay. Melatonin and nitric oxide (NO) concentrations were measured using enzyme immunoassay kits. Moreover, semen collection and evaluation of some sperm parameters were performed once a week. Results revealed decreases (P < 0.05) in the Doppler indices (resistive index, pulsatility index) of the testicular arteries from W2 till W6 in the melatonin group. FSH, LH, and inhibin concentrations did not change between the two groups, while T, E2, IGF-1, NO, and melatonin concentrations increased (P < 0.05) in the melatonin group compared to the control. Estradiol and NO concentrations increased (P < 0.05), coinciding with decreases in the values of Doppler indices. Notable (P < 0.05) improvements in most parameters of semen quality were seen in the melatonin group. In conclusion, melatonin induced a stimulatory effect on TBF in Shiba goats and possibly, it could be a potential to improve male goats fertility.

Examination of jackass (Equus asinus) accessory sex glands by B-mode ultrasound and of testicular artery blood flow by colour pulsed-wave Doppler ultrasound: Correlations with semen production

The accessory sex glands play a major role in the production of seminal plasma, and testicular artery blood flow seems to strongly influence testicular function. However, very little ultrasound imaging of these organs has been undertaken in donkeys. The present work reports the results of such examinations in five jackasses along the year. The accessory glands were inspected by B-mode ultrasound while the testicular artery blood flow was assessed by colour pulsed-wave Doppler ultrasound. The testicular artery was examined at pampiniform plexus (PPT), supratesticular area (ST) and capsular artery (CA). Values were recorded for the total arterial blood flow (TABF), peak systolic velocity (PSV), end-diastolic velocity (EDV), resistive index (RI), pulsatility index (PI) and time average maximum velocity (TAMV). Semen was obtained and assessed for sperm concentration, viability, abnormalities and motility using a CASA system. The bulbourethral glands, prostate and ductus deferens ampullae were relatively larger than in the stallion. Bulbourethral glands and ampullae sizes were inversely correlated with sperm motility. An reduction in blood flow between the level the PPP and the CA was observed, helping to reduce testis temperature and oxygen pressure. Blood flow at the CA showed the strongest correlation with semen production. PI and RI were positively correlated with the CASA motility variable STR (p = .02, p = .06) and sperm viability (p = .01), while sperm concentration (p = .05) correlated inversely with PSV, EDV, TAMV and TABF. EDV also correlated negatively with the CASA variables VSL, LIN, STR and VAP (p ≤ .05). PI and RI were also negatively correlated with testis length (p = .0093, p = -.0438).

Advanced ultrasound techniques in small animal reproduction imaging

Ultrasonography is the imaging technology of choice for the evaluation of the reproduction system and of pregnancy in both humans and animals. Over the past 10 years, there have been significant technological improvements of the equipment, while new technologies have been developed. Doppler, contrast-enhanced ultrasonography, elastography, and 3D/4D ultrasonography are advanced ultrasound techniques that have been designed as methods to increase the diagnostic sensitivity of two-dimensional (b-mode) ultrasound, and not as stand-alone tests. The basic physics as well as the advantages and limitations of these advanced ultrasound methods are briefly described. In the reproductive diagnostics of small animals, these techniques have gained an increased popularity as proved by the increased publication of several reports that are also briefly summarized in this review. Clinical applicability is to date limited because of a lack of research on the diagnostic value in concrete situations. Future research projects should focus also on standardization of the used techniques, on determination of thresholds to discriminate between healthy or diseases or fertile versus infertile and on the predictive value of advanced ultrasound findings. Continuing development and optimization of different ultrasound techniques as well as the increase of related scientific interest and worldwide research promises that the clinical interest on the use of advanced ultrasound techniques will increase in future.

Ultrasonographic characteristics of the testes, epididymis and accessory sex glands and arterial spectral indices in peri- and post-pubertal Nelore and Caracu bulls

Ultrasonography can provide information about the integrity of organs; however, rarely is applied to the reproductive organ evaluation of bulls. The objective of the present study was to characterize and compare values for variables and ultrasonographic characteristics of the testes, epididymis and accessory sex glands, as well as spectral Doppler indices of the testicular and internal iliac arteries, between peri- and post-pubertal Nelore and Caracu bulls. Nelore (n = 203) and Caracu (n = 79) bulls were assigned by age class: peri-pubertal (12-15 months) and post-pubertal (> 22 months). Data were analyzed using SAS's PROC MIXED procedure (P < 0.05). The biometric variables of the testes and cauda epididymis differed between peri- and post-pubertal Nelore and Caracu bulls. There was a difference between breeds for the vesicular glands, ampulla of vas deferens, disseminate portion of the prostate, and craniocaudal dimension of the bulbourethral glands. Echogenicity of the testicular parenchyma differed between breeds and age classes. The pulsatility and resistive indices of the testicular arteries differed between Nelore and Caracu bulls. The biometric and ultrasonographic characteristics of the testes, epididymis and accessory sex glands, as well as of the arterial indices in bulls are affected by genetic group and age class, and when assessed there is useful information regarding the progression of sexual maturation.

Sperm Tail Defects and Abnormal Testicular Blood Flow in a Beagle Dog: A Case Report

A 5-year-old male Beagle dog produced ejaculates with a high percentage of spermatozoa with abnormal morphology, especially sperm tail defects. Although libido and semen volume were normal, ejaculates showed asthenospermia, oligozoospermia, and teratozoospermia. The spermatozoa exhibited morphologic defects affecting the flagellum, mainly coiled tails with or without macrocephalia (33.5 ± 2.1%), bent tails (18.3 ± 3.4%), and proximal cytoplasmic droplets (6.7 ± 2.8%). The peripheral plasma testosterone level was 2.76 ± 0.21 ng/mL. The resistive index and the pulsatility index from marginal and intratesticular vessels measured by Doppler ultrasound showed higher values in the right testicle than in the left testicle. Histologic evaluation revealed focal reduction in the number of germ cells and sperm in the seminiferous tubules in the right testicle. This is the first report that describes simultaneously the presence of sperm tail defects in the ejaculate and changes in the blood flow of testicular vessels in the dog.

Can testicular artery Doppler velocimetry values change according to the measured region in dogs?

Testicular tissue maintenance is performed by the testicular artery, and the hemodynamics of this artery can be evaluated using Doppler ultrasonography. The aim of this study was to characterize the peak systolic velocity (PSV), end diastolic velocity (EDV), pulsatility index (PI) and resistivity index (RI) of five regions of the testicular artery in dogs, including two proposed regions and three that have been previously described. Twenty-two dogs were used, and the PSV, EDV, PI and RI of the testicular artery were measured in five regions: proximal, medial and distal supratesticular; marginal; and intratesticular. The median values for PSV (cm/s), EDV (cm/s), PI and RI in the five regions were as follows: proximal supratesticular (23.1, 3.7, 2.1 and 0.8); medial supratesticular (17.2, 4.5, 1.5, and 0.7); distal supratesticular (12.2, 5.7, 0.8, and 0.5); marginal (11.3, 6.5, 0.5, and 0.4); and intratesticular (5.7, 3.5, 0.5, and 0.4). There was a difference between the PSV of the medial and distal supratesticular regions. There were differences in the PSV, EDV, PI and RI among the distal supratesticular, marginal and intratesticular regions. Measurements of PSV, EDV, PI and RI of the testicular artery in dogs at the proposed regions showed different results due to the hemodynamic and morphological differences of the artery during its course in the spermatic cord and to the testicles. It is necessary to identify the region in testicular artery Doppler velocimetric evaluations of dogs, given that there is a difference according to the region measured.

Changes in testicular size, echotexture, and arterial blood flow associated with the attainment of puberty in Dorper rams raised in a subtropical climate

There is a paucity of information on the relationships of testicular morphology, echotextural attributes, and blood flow dynamics with pubertal development of rams raised in a subtropical climate. Forty-five Dorper rams (24 rams aged 8-11 months and 21 rams aged 12-24 months) were examined using a portable ultrasound scanner connected to a 7.5-MHz transducer. Computer-assisted analyses of testicular ultrasonograms utilized commercially available Image ProPlus^® analytical software. Spectral Doppler scans of testicular arteries were performed immediately after scrotal (B-mode) ultrasonography to determine peak systolic velocity (PSV), end-diastolic velocity (EDV), resistive index (RI = [PSV-EDV]/PSV), and pulsatility index (PI = [SPV-EDV]/mean velocity) of the blood vessels. The length of the testes (9.7 ± 0.3 compared with 9.0 ± 0.2 cm) and scrotal circumference (33.3 ± 0.5 compared with 31.8 ± 0.4 cm) were greater (p < 0.05) but testicular depth (4.5 ± 0.1  compared with 4.9 ± 0.08 cm) was less (p < 0.05) in sexually mature compared with peripubertal rams. [Corrections added on 9 Jan 2019 after initial online publication: The testicular size values in the sentence were corrected.] There were no differences (p > 0.05) between the two age groups of Dorper rams in blood flow indices of testicular arteries. Mean numerical pixel values (100.5 ± 4.1 compared with 89.2 ± 4.8) and pixel heterogeneity (25.6 ± 0.6 compared with 23.6 ± 0.5) of testicular parenchyma were greater (p < 0.05) in peripubertal than in postpubertal rams. Semen volume was negatively correlated with PI of testicular arteries (r = -0.57, p = 0.04). In summary, the attainment of sexual maturity in the rams of the present study was associated with significant changes in testicular length and depth, scrotal circumference, and parenchymal echogenicity/hetrogeneity but not in testicular volume and blood perfusion rates. Testicular artery PI can be used to predict the volume of ejaculate in rams.

Pulse wave Doppler ultrasound of testicular arteries and their relationship with semen characteristics in healthy bulls

BACKGROUND

Semen evaluation is used to estimate the testicular function. In bulls, the spermatozoa present in the ejaculate are the result of a process that begun more than 2 mo earlier, bequeathing a delayed depiction of the actual function of the testis. Since testis vascularization might be critical for the gonad function, selected pulse wave Doppler ultrasound parameters were assessed in this study, for instance the peak systolic velocity, the end diastolic velocity and the resistive index of the testicular artery along the spermatic cord, the marginal portion of the testicular artery and the intratesticular branches of the testicular artery both in healthy adult and young bulls. Correlations between these parameters and characteristics of semen that was collected numerous times, before and after the Doppler ultrasound examination.

RESULTS

The peak systolic velocity and the end diastolic velocity measured in the testicular artery along the spermatic cord (supratesticular artery - SA) were variable among the bulls and within individual bulls, likely due to the convoluted course of the vessel. The resistive index was found highly repeatable in the same bull. A reduction in the resistive index was found between the supratesticular artery and the marginal portion of the testicular artery (P < 0.01), and between the marginal portion of the testicular artery and the intratesticular branches of the testicular artery (P < 0.05). No differences were recorded for the pulse wave Doppler ultrasound parameters in young bulls compared with adults. A significant correlation was found between the resistive index of the marginal portion of the testicular artery and total sperm in the ejaculate (r = 0.516, P < 0.05), the immature sperm (r = 0.462, P < 0.05), the teratoid sperm (r = 0.375, P < 0.05), and the "Dag defect" sperm (r = 0.389, P < 0.05). Similarly, the resistive index of the intratesticular branches of the testicular artery were found correlated with the total sperm number in the ejaculate (r = 0.568, P < 0.05), the immature sperm (r = 0.523, P < 0.05), the teratoid sperm (r = 0.418, P < 0.05), and the "Dag defect" sperm (r = 0.341, P < 0.05).

CONCLUSIONS

The data presented in this study suggest that the resistive index, measured at the marginal portion of the testicular artery, could be an easy-to-perform parameter to evaluate the spermatogenesis quality in young bulls and normal adults.

Pulse Doppler ultrasound as a tool for the diagnosis of chronic testicular dysfunction in stallions

Testicular function is particularly susceptible to vascular insult, resulting in a negative impact on sperm production and quality of the ejaculate. A prompt diagnosis of testicular dysfunction enables implementation of appropriate treatment, hence improving fertility forecasts for stallions. The present research aims to: (1) assess if Doppler ultrasonography is a good tool to diagnose stallions with testicular dysfunction; (2) to study the relationship between Doppler parameters of the testicular artery and those of sperm quality assessed by flow cytometry and (3) to establish cut off values to differentiate fertile stallions from those with pathologies causing testicular dysfunction. A total of 10 stallions (n: 7 healthy stallions and n: 3 sub-fertile stallions) were used in this study. Two ejaculates per stallion were collected and preserved at 5°C in a commercial extender. The semen was evaluated at T0, T24 and T48h by flow cytometry. Integrity and viability of sperm (YoPro®-1/EthD-1), mitochondrial activity (MitoTracker® Deep Red FM) and the DNA fragmentation index (Sperm Chromatin Structure Assay) were assessed. Doppler parameters were measured at three different locations on the testicular artery (Supratesticular artery (SA); Capsular artery (CA) and Intratesticular artery (IA)). The Doppler parameters calculated were: Resistive Index (RI), Pulsatility Index (PI), Peak Systolic Velocity (PSV), End Diastolic Velocity (EDV), Time Average Maximum Velocity (TAMV), Total Arterial Blood Flow (TABF) and TABF rate. The capsular artery was the most reliable location to carry out spectral Doppler assessment, since blood flow parameters of this artery were most closely correlated with sperm quality parameters. Significant differences in all the Doppler parameters studied were observed between fertile and subfertile stallions (p ≤ 0.05). The principal components analysis assay determined that fertile stallions are characterized by high EDV, TAMV, TABF and TABF rate values (high vascular perfusion). In contrast, subfertile stallions tend to present high values of PI and RI (high vascular resistance). The ROC curves revealed that the best Doppler parameters to predict sperm quality in stallions were: Doppler velocities (PSV, EDV and TAMV), the diameter of the capsular artery and TABF parameters (tissue perfusion parameters). Cut off values were established using a Youden´s Index to identify fertile stallions from stallions with testicular dysfunction. Spectral Doppler ultrasound is a good predictive tool for sperm quality since correlations were determined among Doppler parameters and markers of sperm quality. 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.