Testicular ultrasonogram pixel intensity during sexual development and its relationship with semen quality, sperm production, and quantitative testicular histology in beef bulls

N-Acetylcysteine Supplementation Improves Testicular Haemodynamics, Testosterone Levels, Seminal Antioxidant Capacity and Semen Quality in Heat-Stressed Goat Bucks

Heat stress (HS) disrupts testicular homeostasis because of oxidative stress. N-acetylcysteine (NAC) is a thiol compound with antioxidants, anti-inflammatory and anti-apoptotic properties. As a sequel, this research aimed to assess the ameliorative effects of NAC supplementation on the reproductive performance of goat bucks kept under environmental HS. Primarily, Doppler examination as well as semen collection and evaluation were conducted on 12 mature bucks for 2 weeks (W) as pre-heat stress control (W1 and W2) during winter (February 2023). The temperature-humidity index (THI) was 63.4-64.3 (winter season). Then during summer HS conditions (from the beginning of July till the end of August 2023) bucks were assessed before NAC supplementation (W0), afterwards they were arbitrarily assigned into two groups. The control group (CON; n = 6) received the basal diet while the NAC group (n = 6) received the basal diet in addition to oral NAC daily for 7 weeks (W1-W7). The THI was 78.1-81.6 (summer season). Testicular blood flow parameters, serum concentration of nitric oxide (NO) and testosterone were measured. Additionally, total antioxidant capacity (TAC) and malondialdehyde (MDA) content in seminal plasma and semen quality parameters were evaluated. There were marked reductions (p < 0.05) in the resistive index (RI; W1, W4 and W5), pulsatility index (PI; W2 and W4-W7), and systolic/diastolic ratio (S/D; W4-W7) in the NAC group compared to the CON group. Furthermore, testosterone and NO levels were higher (p < 0.01 and p < 0.05, respectively) in the NAC group (W2, W3, W5 and W3-W5, respectively). Seminal plasma TAC increased (p < 0.05) and MDA decreased (p < 0.05) in the NAC group (W2, W4 and W5) compared to the CON group. Moreover, there were marked improvements (p < 0.05) in semen quality parameters (mass motility, total motility, viability and normal morphology) in the NAC group. In conclusion, oral NAC supplementation could be used to enhance the reproductive performance of goat bucks during HS conditions which is supported by remarkable enhancement in testicular haemodynamics, NO, testosterone levels and semen quality parameters.

Outcomes of dietary alpha-lipoic acid on testicular vascularization, steroid hormones, and seminal quality in aged Baladi bucks

BACKGROUND

Senescence is accompanied by a progressive decrease in male reproductive performance, mainly due to oxidative stress and endothelial dysfunction. Alpha lipoic acid (ALA) is a potent antioxidant, that diffuses freely in aqueous and lipid phases, possessing anti-inflammatory and anti-apoptotic properties. This study aimed to examine the effects of supplemental dietary ALA on testicular hemodynamics (TH), circulating hormones, and semen quality in aged goats. Twelve Baladi bucks were divided into two groups (n = 6 each); the first fed a basic ration and served as a control group (CON), while the second received the basic ration supplemented with 600 mg ALA/ kg daily for consecutive eight weeks (ALA).

RESULTS

There were improvements in testicular blood flow in the ALA group evidenced by a lower resistance index (RI) and pulsatility index (PI) concurrent with higher pampiniform-colored areas/pixel (W3-W6). There were increases in testicular volume and decreases in echogenicity (W3-W5; ALA vs. CON). Compared to the CON, ALA-bucks had higher serum concentrations of testosterone, estradiol, and nitric oxide (W3-W5). There were enhancements in semen traits (progressive motility, viability, morphology, and concentration, alanine aminotransferase enzyme) and oxidative biomarkers (catalase, total antioxidant capacity, and malondialdehyde).

CONCLUSIONS

ALA dietary supplementation (600 mg/kg diet) improved aged bucks' reproductive performance by enhancing the testicular volume, testicular hemodynamics, sex steroids, and semen quality.

Ultrasonography of Testicular Maturation and Correlation with Body Growth and Semen Evaluation in Beagle Dog Model

This prospective study investigated the ultrasonographic appearance of the canine testis from birth to adulthood. Eight purpose-bred laboratory Beagle-breed dogs were monitored from 4 to 40 weeks of life. The following parameters were evaluated every two weeks: bodyweight and height, scrotal and testicular volume, ultrasonographically measured testicular volume, echogenicity, heterogeneity, blood-flow score, ratio of the grayscale intensity value of the testis to the capsule, ejaculate volume, motility, viability, and number of spermatozoa. A correlation analysis was carried out between the various measurements obtained. Fertility was achieved in the 36th week of life. The echogenicity of the testicular parenchyma increased with age, and subsequently to the 30th week of life remained constant. The heterogeneity of the testicular parenchyma, as was evaluated by the standard deviation of the values of grayscale intensity of the parenchyma, also increased with age and was >19 at the onset of fertility. The ratio of grayscale intensity of testicular parenchyma had values < 200 at maturity. A colour Doppler evaluation first detected blood flow in the testis in the 22nd week. After the 32nd week, distinct signals were visible. In the 36th week, >80% of the testes imaged had visible vessels. A significant correlation was found between all the evaluation methods. The findings of the study may help clinicians detect the onset of fertility in dogs, especially when semen evaluation is not feasible; however, their applicability in all breeds or individuals might possibly vary due to genetic, physiological, and developmental differences. In summary, the study ultrasonographically explores the testicular maturity in dogs, with the aim to improve clinical assessments and health management in these animals.

Diagnostic Approach to Equine Testicular Disorders

Management of breeding stallions is crucial to equine reproduction. The longevity of the breeding career is the ultimate objective, whether the stallion is used for natural cover or for semen collection and artificial insemination. Stud farm veterinarians should be aware of the techniques used to evaluate testicular function and the diagnostic approach to testicular disorders in cases of emergency. This paper presents the clinical methods used to evaluate testicular health, including palpation, ultrasonography, biopsy, and fine-needle aspiration. The discussion of testicular disorders is broken down into four categories: congenital disorders (cryptorchidism, monorchidism, and testicular hypoplasia), differential diagnosis of scrotal enlargement, differential diagnosis of causes of progressive testicular enlargement, and differential diagnosis of testicular asymmetry or reduction in size with an emphasis on testicular degeneration. The sudden increase in testicular size is often accompanied by severe clinical signs and is a major cause for referral of stallion for surgery. Testicular disorders are illustrated with clinical cases seen by the authors.

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.

Stiffness estimated by strain elastography reflects canine testicular spermatogenesis and histology

Ultrasound elastography was proposed for the evaluation of testicular focal lesions, but no studies verified the agreement between the whole histological architecture of the testis and the stiffness measured by elastography. The present study explored the use of strain elastography in the evaluation of testis with normal or abnormal spermatogenesis, classified based on epididymal sperm attributes, and the consistency between elastographic parameters and the testicular histological feature. Strain elastography was performed during the routine andrological examination in 22 dogs presented for elective orchiectomy. Epididymal sperm attributes and testicular histology were analyzed after orchiectomy. Based on the epididymal sperm characteristics, testes were classified according to normal or abnormal spermatogenesis, and strain elastographic attributes were compared between groups. Possible correlations between strain elastography and histological features were also explored. Consistent with the literature in humans, testes with abnormal spermatogenesis were stiffer (mean strain elastographic index 3.6 ± 0.6) compared with normal testes (mean strain elastographic index 1.9 ± 0.2; P < 0.01). The strain elastographic index was negatively correlated with the area occupied by seminiferous tubules (Pearson's rho = -0.716; P = 0.0003), the mean diameter (Pearson's rho = -0.742; P = 0.0002), and thickness of the seminiferous tubule (Pearson's rho = -0.728; P = 0.0002). Surprisingly, no correlations were found between the area occupied by connective tissue in histological sections and elastographic attributes, suggesting that the increased stiffness was not related to the increased amount of connective tissue. This study demonstrated that strain elastography could be used to support the andrological examination, but measurements should be acquired in specific regions to be reliable.

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.

Diurnal rhythms in testicular blood flow, testicular morphometry and reproductive hormones in Shiba goats

Context Testicular blood flow (TBF) is crucial for testicular function. The pattern of TBF in Shiba goats indicates seasonal variations. Aims This study aimed to investigate the effect of diurnal variations on TBF, testis volume (TV), testicular echogenicity, and reproductive hormones in goats over a 24-h period. Methods In three trials that went for three consecutive days each, 12 bucks were scanned using Triplex ultrasonography to assess the TV, pixel intensity of testicular echotexture (PIX), and Doppler indices of TBF (resistive index: RI and pulsatility index: PI) in four-time points a day (at 6.00, 12.00, 18.00, and 00.00 h). Concomitantly, the changes in circulating FSH, LH, inhibin, testosterone (T), estradiol (E2), cortisol, and melatonin were assessed. Key results Results revealed diurnal alterations in the calculated RI of TBF and the PIX of testicular parenchyma (P < 0.05). Lower RI values of the TBF were observed at 6.00 h compared to other time points. There were significant diurnal alterations in the levels of FSH (P < 0.05), LH (P < 0.05), T (P < 0.0001), E2 (P < 0.0001), cortisol (P < 0.0001), and melatonin (P < 0.0001). FSH attained a higher concentration at 18.00 h compared to 12.00 h. Concentrations of LH were significantly higher at 06.00 h compared to those at 18.00 h. Concentrations of T were significantly higher at 6.00 compared to other time points. E2 showed higher concentrations at 6.00 h and 00.00 h compared to 12.00 h and 18.00 h. On the contrary, concentrations of cortisol were significantly higher at 12.00 h and 18.00 h compared to 06.00 h and 00.00 h. The highest concentrations of melatonin were observed at 00.00 h compared to other time points, while the lowest concentrations were at 12.00 h. Conclusions Diurnal rhythm induces significant changes in TBF, testicular PIX, and circulating FSH, LH, T, E2, cortisol, and melatonin over the 24-h day. Implications The outcomes of the study are reflected in the advisability of monitoring the TBF at a fixed time a day to avoid the circadian rhythm effect.

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.

Coenzyme Q10 Supplementation enhances testicular volume and hemodynamics, reproductive hormones, sperm quality, and seminal antioxidant capacity in goat bucks under summer hot humid conditions

Oxidative stress (OS) is brought on by heat stress (HS), which weakens antioxidant defense and initiates OS. Since mitochondria are the primary source of reactive oxygen species (ROS), HS-mediated OS may be lessened by targeting mitochondria with particular antioxidants. The purpose of this study was to investigate the effect of oral coenzyme Q10 (CoQ10) supplementation on the reproductive performance of goat bucks under HS conditions. Ten mature bucks were randomly separated into two groups and housed in an environment with a high-temperature humidity index (THI: 88.3 to 94.8; summer season). The first group (n = 5) got the baseline diet while the second group (n = 5) received supplemental oral CoQ10 (3 mg/kg BW; CoQ10 group) daily for six weeks. Testicular blood flow parameters (TBF), testicular volume (TV) and echogenicity (TE), nitric oxide (NO), seminal alanine aminotransferase (ALT) and catalase (CAT) activities, total antioxidant capacity (TAC), malondialdehyde (MDA) content, and semen quality traits were all measured. The examinations started a week before (W-1), on the first supplementation day (W0), and weekly for eight consecutive weeks (W1-W8). There were marked (P < 0.05) increases in TBF (W3-W6) and TV, and a decrease in TE (W3-W5) in the CoQ10 group compared to the CON group. Similarly, testosterone (T) and NO levels (W3-W5) in the CoQ10 group were higher (P < 0.05) than those of the control group. The CoQ10 group demonstrated significant (P < 0.05) increases in seminal CAT (W4-W8) and TAC (W2-W6) activities and decreases in ALT (W4-W7) activity and MDA (W5-W8) concentration as compared to the control group. The CoQ10 group showed improvements (P < 0.05) at W3-W6 for sperm progressive motility, viability, and normal morphology and at W6-W8 for sperm concentration. In conclusion, oral CoQ10 supplementation improved testicular hemodynamics, testosterone production, semen quality, and antioxidant capacity in goat bucks during summer heat stress conditions.

Exogenous L-carnitine Administration Ameliorates the Adverse Effects of Heat Stress on Testicular Hemodynamics, Echotexture, and Total Antioxidant Capacity in Rams

Heat stress (HS) diminishes the testicular antioxidant defense systems, which adversely affect the testicular blood perfusion. Improving the testicular hemodynamics during HS conditions is of a great impact on the whole reproductive performance in rams. This study aimed to evaluate the ameliorative effects of L-carnitine (LC) on the testicular blood flow and echotextures and also on the total antioxidants (TAC) and nitric oxide (NO) concentrations in the serum during HS conditions in rams. Testicular blood flow was evaluated through scanning of the supra-testicular artery (STA) spectral patterns through pulsed Doppler ultrasonography [peak systolic velocity (PSV), end-diastolic velocity (EDV), time average maximum velocity (TAMAX), resistive index (RI), and pulsatility index (PI)], while the echotexture assessment of testicular parenchyma was performed by a computerized software program. Moreover, TAC and NO concentrations were assayed colorimetrically using the spectrophotometer. There were significant decreases (P &lt; 0.05) in values of PSV at 48 and 168 h (23.45 ± 0.39 and 23.37 ± 1.41 cm/s, respectively), and TAMAX at 1, 48, and 168 h (17.65 ± 0.95, 17.5 ± 0.13, and 16.9 ± 1.05 cm/s, respectively) after LC administration compared to just before administration (31.92 ± 1.13 and 21.58 ± 0.92 cm/s, respectively). Values of RI and PI of the examined STA significantly decreased, especially at 1 h for RI (0.45 ± 0.02) and 1 and 48 h for PI (0.66 ± 0.06 and 0.65 ± 0.05, respectively) after LC treatment to 0 h (0.55 ± 0.03 and 0.84 ± 0.06, respectively). The EDV values did not show any significant (P &lt; 0.05) changes in all the experimental time points. There were significant (P &lt; 0.05) increases in the values of pixel intensity of the testicular parenchyma, especially at 1 and 168 h (78.71 ± 2.50 and 88.56 ± 4.10, respectively) after LC administration, compared to just before administration (69.40 ± 4.75). Serum NO levels tend to increase after LC administration (P = 0.07) concerning just before administration. While TAC values showed significant gradual increase and reached the highest values at 168 h (2.75 ± 0.58 mM/l) after LC administration, compared to 0 h (1.12 ± 0.05 mM/l). In conclusion, exogenous LC administration ameliorates testicular hemodynamic disruptions, as measured by spectral Doppler ultrasonography, via augmentation of the rams' total antioxidant capacity under HS conditions.

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.

Reproductive parameters of Bos taurus and Bos indicus bulls during different seasons in tropical conditions: focus on an alternative approach to testicular assessments using ultrasonography

The aim of the present study was to evaluate the reproductive status of Bos taurus and Bos indicus bulls during different seasons when bulls were in a tropical environment focusing on systematic assessment of the testes using B-mode ultrasonography and ImageJ software to evaluate the testicular parenchymal tissues. The experimental design is a 2 × 2 factorial arrangement, with breed (Bos Taurus - Simmental; Bos indicus - Nellore) and season (summer; winter) as factors. Testicular ultrasonic evaluation and conventional semen analysis were performed. The Simmental bulls had more major sperm defects than Nellore bulls in the summer (P = 0.0001). Additionally, Simmental bulls had a greater percentage of major sperm defects during the summer than winter months P = 0.045). Furthermore, Nellore bulls had a greater testicular parenchyma echogenicity, with a greater grayscale, (caudal parenchyma, P = 0.0155; cranial parenchyma, P = 0.001) and mediastinum grayscale than Simmental bulls (Nellore = 52.32 ± 03.60; Simmental = 35.72 ± 03.67; P = 0.003). Simmental bulls also had a greater testicular lesion area (P = 0.0147). Results indicated there was susceptibility to heat stress when Simmental bulls were maintained in tropical regions. The results of the present study indicate there is an association between results when there was use of conventional andrological evaluation procedures and results from ultrasonic analysis using ImageJ software that allows for earlier identification of tissue aberrations that could lead to impaired semen quality and fertility.

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.

Relationship between pubertal testicular ultrasonographic evaluation and future reproductive performance potential in Piétrain boars

New ways of predicting sperm quality and output performance in young artificial insemination (AI) boars are important for breeding companies to ensure that the pubertal boars delivered to the AI studs have a high chance of meeting minimum quality standards to be used for insemination and therewith dissemination of desirable characteristics. The aim of the current study was to characterize the testicular development of 218 pubertal Piétrain boars (Line 408, Pig Improvement Company) to identify traits with predictable characteristics relative to their sperm quality as an adult AI boar. Scrotum, testes and epididymis were examined ultrasonographically at day (d) 100 (on-test) and 170 (off-test) followed by a computer-assisted grayscale analysis (GSA). Over the test period, paired testicular volume increased 7.3-fold from 22.7 ± 10.8 cm³ to 166.6 ± 62.2 cm³. The right testis was significantly (P = 0.014) larger than the left one at the off-test. Based on the sperm quality (ejaculate volume, sperm concentration, total sperm number, morphologically abnormal sperm and total sperm motility at day 3 of semen storage), 82.11% (n = 179) of the boars were classified as "productive" boars. These boars had a significantly (P = 0.039) larger paired testicular volume than "non-productive" boars (45.9 ± 19.9 cm³vs. 38.5 ± 12.6 cm³) at the on-test. For the right testis at on-test, significant differences for the standard deviation of mean gray value (P = 0.022), area under the curve (P = 0.004) and mean gradient value (GRAD, P = 0.030) regarding the future sperm production capacity (SPC) were shown. At off-test, there was a significant difference for minimum gray value (MIN GV, P = 0.003) and mean gray value (P = 0.001) related to SPC. To find SPC related cut-off values for GSA data, a two segmental non-linear regression analysis was carried out indicating breakpoints for GRAD ≥12 and MIN GV ≥ 40 for boars with low SPC. Off-test boars with MIN GV ≥ 40 showed a 2.4 higher risk to display low SPC (Odds ratio = 2.4 [1.1, 5.4]; P = 0.024). The results may enable breeding companies to include new sperm quality associated traits in their boar testing and selection programs.

Inhibitory effects of long-term repeated treatments of a sustainable GnRH antagonist, degarelix acetate, on caprine testicular functions

We investigated the effects of long-term repeated treatments with a sustainable gonadotropin-releasing hormone (GnRH) antagonist, degarelix acetate, on testicular hormonal secretion, size, ultrasound images, histology and spermatogenesis in goats to assess its efficacy as a chemical castration method. Male Shiba goats (3–6 months of age) were treated subcutaneously with degarelix acetate every 4 weeks for 24 weeks. Plasma testosterone and insulin-like peptide 3 concentrations decreased (P < 0.05) within 2 days after the first treatment and remained low until 29 weeks (P < 0.05). Scrotal circumference and testicular pixel intensity were lower from 2–6 months and from 1–6 months, respectively, compared to the pretreatment values (P < 0.05). The testis and epididymis weights were lower at 24 weeks compared to those in untreated goats (P < 0.05). There were no sperm in the seminiferous tubules of testicular tissue sections or in homogenates of the epididymis at 24 weeks. These results suggest that repeated treatment with degarelix acetate is an effective chemical castration method for goats.

Feline testicular ultrasonogram differentiates pre vs. postpubertal and normal vs. disrupted spermatogenesis

The aims of this study were: to ultrasonograhically describe and compare testicular parenchyma echogenicity and heterogeneity using digital image analysis in: I) prepubertal (PREP), peripubertal (PERI) and mature (MAT) cats; II) Normal and abnormal mature felids. Secondary, the relationships between histomorphological and ultrasonographic attributes of the testes were also determined. I) Fourteen, PREP, PERI and MAT male cats were ultrasonographically examined and then castrated. II) Seven adult cats were ultrasonographically examined before and after a GnRH antagonist administration and then castrated. All the testes were grossly and histomorphometrically assessed. In the frozen digital images of the longitudinal ultrasound sections, 3 regions of interest (ROI, 1 mm2) were selected. Within each ROI the echogenicity and the heterogeneity of the testicular parenchyma were digitally analyzed. In experiment I, testicular volume (0.15 ± 0.0 vs. 0.49 ± 0.1 vs. 1.65 ± 0.1; P < 0.01) and gonadosomatic index (0.04 ± 0.0 vs. 0.05 ± 0.0 vs. 0.08 ± 0.0; P < 0.01), echogenicity (56.54 ± 0.75 vs. 81.87 ± 5.88 vs.94.67 ± 3.62; P < 0.01) and heterogeneity (10.2420 ± 1.3740 vs.13.65 ± 0.65 vs. 14.67 ± 1.49; P < 0.01) augmented throughout PRE, PERI, and MAT. In experiment II, testicular volume (1.00 ± 0.09 vs. 0.85 ± 0.09; P < 0.05), echogenicity (87.74 ± 1.53 vs. 83.32 ± 1.54; P 0.01) but not heterogeneity (14.09 ± 0.26 vs. 14.19 ± 0.29; P > 0.05) decreased in the post GnRH antagonist abnormal testes. For both experiments, testicular volume, seminiferous tubular diameter, percentage of spermatids as the most mature cell type, and luminal/intertubular ratio were highly correlated (P < 0.01) with their echotextural attributes. Computer-assisted image analysis of B mode ultrasonogram appears as a good indicator of pubertal development and mild alterations of spermatogenesis in felids.

Histological Comparison of Testicular Needle Biopsy and En Bloc Samples in Abattoir Calves

the aim of this study was to test whether a single testicular needle biopsy could provide histological results comparable to en bloc resection histology and whether one biopsy was sufficient to reflect the histology of an entire pair of testicles. Two methods of sample collection were tested on 32 bull calves aged five to eight months to compare histological parameters of needle biopsy with those of en bloc resection samples. One testicular needle biopsy of the right and three en bloc samples of both testicles were collected and compared for the number of tubular cross sections, tubules with elongated spermatids (ES), outer/inner diameter of tubules, thickness of tubular wall, and number of Sertoli cells (SC). Additionally, animal data were considered. No significant differences were found between the left and right testis or among the individual locations of en bloc samples. However, histologically significant differences (Bonferroni-adjusted significance level: p < 0.05/6 = 0.0083) were found between the needle biopsy and en bloc resection regarding the tubular cross sections per visual field (p < 0.05), the outer (p = 0.01) and inner diameter and the thickness of the tubular wall (both p < 0.01). In the SOX9 immunohistochemical staining, no significant differences (p > 0.05) could be observed for SC numbers between needle biopsy and en bloc samples. In conclusion, results of testicular needle biopsy do not have the same validity as the en bloc resection histology. Furthermore, one biopsy is insufficient to reflect the histology of the entire testicular pair.

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.

Effects of immunocastration performed at two live weights on the growth physiology, temperament and testicular development of feral beef bulls

The aim of this study was to examine the effect of administering an anti-gonadotropin-releasing hormone vaccine (Improvac^® , developed for pigs) on the performance, temperament, testicular development, and hormone and metabolite profiles of feral bulls (Bos taurus) vaccinated at two different live weights (LW). In all, 16 Serrana de Teruel animals were involved in this 2 x 2 factorial design using the factors LW (LIGHT vs. HEAVY) and vaccine treatment (control, C vs. vaccinated, VA). All animals received the same diet (ad libitum concentrate plus straw) over a 164-day fattening period. Temperament was assessed using chute and flight speed tests. Testicular diameter and subcutaneous fat thickness were recorded. Testosterone, IGF-1, urea, NEFA, and creatinine profiles were analyzed. Bull weight gain was reduced in VA compared to C animals, regardless of the initial LW. The vaccine did not affect the temperament tests, subcutaneous fat thickness or NEFA and creatinine concentrations and had minor effects on linear body measures. The vaccine inhibited testicular growth, reduced plasma testosterone to residual levels, and increased urea concentrations. LIGHT-C animals exhibited increased mean plasma IGF-1 concentrations compared to LIGHT-VA animals. In conclusion, vaccination reduced bull growth and sexual development irrespective of LW at immunization.

Effects of an anti-gonadotrophin releasing hormone vaccine on the morphology, structure and function of bull testes

Castration reduces aggressive and sexual behaviour and provides better carcass quality in bull calves. Vaccination against gonadotrophin-releasing hormone (GnRH) is used as an alternative to surgical castration for the purposes of reducing pain and distress in the animals. Currently, no anti-GnRH vaccine has been authorized for use in cattle in the European Union. The aim of the present study was to assess the effect of an anti-GnRH swine-specific vaccine (Improvac®, Zoetis, USA) on the morphology, structure and function of bull testes. Animals were vaccinated at days 1, 21 and 104 of the experimental period and were classified based on their live weight into the following two groups: LIGHT (172.9 ± 30.00 kg) and HEAVY (323.8 ± 37.79 kg). The scrotal circumference was measured on day 1 and prior to slaughter (day 164). At slaughter, the sperm motility and concentration in the caudae epididymis were assessed. Testes were weighed, measured and examined using ultrasound, and then tissue samples were collected and fixed in formalin. Histological and immunohistochemical studies were performed on the testes to measure the diameter of the seminiferous tubules and assess the testicular cell populations. The results revealed that suppression of testicular development was associated with the use of the Improvac® vaccine, which resulted in a smaller size of the testes and impaired spermatid production. However, the effect of Improvac® was more pronounced and consistent in calves vaccinated at a low live weight than at a heavy live weight, which suggested that vaccination is more effective when calves are vaccinated before or early during puberty. However, testes from calves vaccinated at a low live weight were more prone to the development of intraluminal concretions in the seminiferous tubules.

Evaluation of hepatic tumor portal perfusion using mesenteric angiography: A pilot study in 5 dogs

BACKGROUND

Mesenteric angiography is a sensitive method for visualizing portal perfusion in the dog.

OBJECTIVES

To evaluate hepatic portal perfusion in dogs with incompletely resectable hepatic tumors using mesenteric angiography.

ANIMALS

Five client-owned dogs with incompletely resectable hepatic tumors evaluated with mesenteric angiography.

METHODS

Retrospective case series. Electronic medical records at the Animal Medical Center were analyzed to identify dogs that underwent mesenteric portography to determine blood flow to nonresectable hepatic tumors and subsequently determine ideal routes for transarterial embolization, vascular stent placement, or both. The images obtained from mesenteric angiography were analyzed and compared to those obtained from computed tomography angiography.

RESULTS

Portography was accomplished using direct mesenteric venography in 3 dogs with hepatocellular carcinoma (HCC), cranial mesenteric arteriography in 1 dog with hepatic adenoma or well-differentiated HCC, and via splenic arteriovenous fistula in 1 dog with diffuse hepatic hemangiosarcoma metastases. Mean pixel densities in areas of hepatic tumor growth identified statistically significant decreases in portal blood flow (P = .02) compared to normal hepatic parenchyma.

CONCLUSIONS AND CLINICAL IMPORTANCE

Initial findings indicate that the blood supply to large and metastatic hepatic tumors in dogs may correlate with that in humans, such that the majority of the tumor blood supply arises from the hepatic artery and not the portal vein. Differences in blood supply between normal hepatic parenchyma and hepatic tumors might be exploited by developing selective tumor therapies such as arterial embolization or chemoembolization that largely spare normal liver tissue. Further investigation is warranted.

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.

Canine reproductive ultrasound examination for predicting future sperm quality

The reproductive potential of male animals is commonly evaluated using a breeding soundness examination incorporating B-mode ultrasound examination of the testes and recently Doppler ultrasound examination of the testicular arteries. These techniques may detect testicular normality or pathology, and while some measured parameters are associated with semen quality at the time of ultrasound examination, few studies have investigated the relationship with future semen quality. We hypothesized that B-mode and Doppler ultrasound measurements would correlate with future semen quality. Within two studies, we investigated the relationship between ultrasound measured testicular volume, testicular echogenicity, testicular homogeneity, subjective assessment of the testicular parenchyma, testicular artery resistance index, and pulsatility index with subsequent semen quality. Fifty-five normal fertile dogs of which 29 had stable semen quality and 26 had a subsequent decline in semen quality were examined during a 6-month period commencing 62 days after the ultrasound examination. Statistical analysis showed that no ultrasound parameters were predictive of future total sperm output or percentage live normal sperm. However, mean testicular echogenicity was positively related to future sperm motility (t = 2.202, p = .039). We conclude that quantitative ultrasound assessment of the appearance of the testicular parenchyma has potential for the evaluation of future semen quality in dogs.

The value of trans-scrotal ultrasonography at bull breeding soundness evaluation (BBSE): The relationship between testicular parenchymal pixel intensity and semen quality

Bull breeding soundness evaluation (BBSE) is commonly undertaken to identify bulls that are potentially unfit for use as breeding sires. Various studies worldwide have found that approximately 20% of the bulls fail their routine prebreeding BBSE and are therefore considered subfertile. Multiple articles describe the use of testicular ultrasound as a noninvasive aid in the identification of specific testicular and epididymal lesions. Two previous studies have hypothesized a correlation between ultrasonographic testicular parenchymal pixel intensity (PI) and semen quality; however to date, no published studies have specifically examined this link. The aim of this study, therefore, was to assess the relationship between testicular parenchymal PI (measured using trans-scrotal ultrasonography) and semen quality (measured at BBSE), and the usefulness of testicular ultrasonography as an aid in predicting future fertility in bulls, in particular those that are deemed subfertile at the first examination. A total of 162 bulls from 35 farms in the South East of Scotland were submitted to routine BBSE and testicular ultrasonography between March and May 2014, and March and May 2015. Thirty-three animals failed their initial examination (BBSE1) due to poor semen quality, and were re-examined (BBSE2) 6 to 8 weeks later. Computer-aided image analysis and gross visual lesion scoring were performed on all ultrasonograms, and results were compared to semen quality at BBSE1 and BBSE2. The PI measurements were practical and repeatable in a field setting, and although the results of this study did not highlight any biological correlation between semen quality at BBSE1 or BBSE2 and testicular PI, it did identify that gross visual lesion scoring of testicular images is comparable to computer analysis of PI (P < 0.001) in identifying animals suffering from gross testicular fibrosis.

How ultrasound technologies have expanded and revolutionized research in reproduction in large animals

Gray-scale ultrasonic imaging (UI) was introduced in 1980 and initially was used to examine clinically the reproductive tract of mares. By 1983 in mares and 1984 in heifers/cows, UI had become a tool for basic research. In each species, transrectal gray-scale UI has been used extensively to characterize follicle dynamics and investigate the gonadotropic control and hormonal role of the follicles. However, the use of transrectal UI has also disclosed and characterized many other aspects of reproduction in each species, including (1) endometrial echotexture as a biological indicator of circulating estradiol concentrations, (2) relative location of the genital tubercle for fetal gender diagnosis by Days 50 to 60, and (3) timing of follicle evacuation during ovulation. Discoveries in mares include (1) embryo mobility wherein the spherical conceptus (6-16 mm) travels to all parts of the uterus on Days 11 to 15, (2) how one embryo of a twin set eliminates the other without self-inflicted damage, and (3) serration of the granulosum of the preovulatory follicle opposite to the future rupture site as an indicator of imminent ovulation. Studies with color-Doppler UI have shown that vascular perfusion of the endometrium follows the equine embryo back and forth between uterine horns and follows the expansion of the bovine allantochorion throughout each horn. In heifers, blood flow in the CL increases during the ascending portion of an individual pulse of PGF2α metabolite and then decreases. These examples highlight the power of UI in reproduction research. Without UI, it is likely that these and many other findings would still be unknown.

Correlations among ultrasonographic and microscopic characteristics of prepubescent ram lamb testes

The onset of spermatogenesis during prepubertal development is accompanied by dynamic changes in testicular microstructure. Computer-assisted analysis of scrotal ultrasonograms may allow us to track these changes in a noninvasive manner; however, the echotextural characteristics of different histomorphological variables remain unclear. Hence the objective of this study was to compare echotextural and microscopic attributes of the testis over the first wave of spermatogenesis in prepubescent ram lambs. Bi-weekly ultrasound examinations and weekly testicular biopsies were carried out in 22 ram lambs from 9.5–10 weeks of age or the attainment of 15 cm3 in testicular volume, respectively, to the first detection of elongated spermatids (ESt). Testicular echogenicity was highly variable with age; however, after the alignment of data to the first detection of ESt, there was an initial increase followed by a decline, corresponding to the mitotic and postmitotic phases of spermatogenesis in prepubescent ram lambs. Testicular echotextural attributes (mean numerical pixel values and pixel heterogeneity) correlated with seminiferous tubule (ST) diameter, the number of degenerating cells/ST cross-section (XS), and the number of ubiquitin C-terminal hydrolase L-1 (a marker for prespermatogonia and undifferentiated spermatogonia) staining cells/ST XS during the mitotic and postmitotic phases. Additionally, in the postmitotic phase, significant correlations were recorded between the quantitative echotextural characteristics and ST cell density, nuclear:ST area and percentages of STs with different spermatogenic cells as the most mature germ cell type present. These results indicate that ram testes exhibit distinctive echotextural characteristics during the mitotic and postmitotic phases of germ cell differentiation. It is concluded that scrotal ultrasonography in conjunction with computerized image analysis holds potential as a noninvasive alternative to testicular biopsy in monitoring the reproductive status throughout different stages of testicular development.

Ultrasonography for monitoring reproductive function in the bull

Diagnostic ultrasonography has been widely used for examination of the reproductive tract of female cattle, but more sparingly in bulls. Typical clinical ultrasonographic examinations of bull testes are unlikely to affect semen quality or sperm production. The ultrasonographic anatomy of bull testes and accessory sex glands has been reported. Although testicular echogenicity increased (i.e. the parenchyma appeared more white) as a bull approached puberty, echogenicity was not superior to scrotal circumference as a predictor of puberty. Ultrasonography can be used to detect and characterize testicular pathology. It is noteworthy that areas of increased echogenicity (testicular fibrosis) are common, especially in young bulls, but are not associated with decreased semen quality (e.g. percentage of morphologically abnormal sperm). Neither visual evaluation nor computerized pixel analysis of testicular ultrasonic echotexture was consistently predictive of semen quality in bulls. Therefore, we concluded that the primary clinical use of ultrasonography in assessment of reproductive function in the bull is characterization of grossly detectable lesions in the testes and scrotum.