Effect of xylazine sedation on testicular blood flow, testicular echotexture, and circulating hormones in Shiba goats

Under field conditions, sedation may be required for a full assessment of the reproductive potential of farm animals. The present study aimed to investigate the effect of xylazine sedation on testicular hemodynamics (TBF), echotexture, testicular volume (TV), and circulating hormones in goats. Sixteen male Shiba goats were sedated using the recommended dose of xylazine (0.05 mg/Kg BW). Testicular hemodynamics were evaluated using color-pulsed Doppler ultrasonography before and after sedation. Echotexture of the testicular parenchyma and TV were assessed using computerized image analysis. Concentrations of testosterone, estradiol (E2), inhibin, cortisol, follicle-stimulating hormone (FSH), and luteinizing hormone (LH) were measured using radioimmunoassay. There were no effects of xylazine sedation in TBF, TV, testicular parenchyma parameters, and concentrations of testosterone, inhibin, FSH, and LH (P ˃ 0.05). However, after sedation, there was significantly (P ˂ 0.05) lower cortisol and E2 concentration (42.88 ± 6.79 ng/ml and 2.47 ± 0.58 pg/ml, respectively) than before sedation (94.89 ± 13.74 ng/ml and 8.65 ± 1.79 pg/ml, respectively). The required time to perform the full scanning of the testis was significantly lower (8.50 ± 0.38 min) after xylazine sedation compared to the non-sedated goats (25.75 ± 1.14 min). In conclusion, xylazine sedation may be practically recommended for the evaluation of TBF in goats because it did not significantly alter velocities parameters and Doppler indices of blood flow within the testicular arteries. Most plasma hormones did not significantly change; however, E2 and cortisol were significantly reduced after xylazine administration.


Introduction
Goats are important animals because of their contributions as a source of meat, milk, and hide production. Moreover, goats are considered an important model for studying the physiology of ruminants (Samir et al. 2018a), and an attractive animal candidate for various experimental protocols in human cardiology and vascular disorders (arrhythmic studies and surgical correction of heart valves) owing to the similarities to the humans' heart (vertical orientation and heart size) (Remes et al. 2008).
For proper assessment of the reproductive performance of male goats, there are many tools such as assessment of semen quality, measuring the scrotal circumference, and hormonal concentrations. Ultrasonography of the reproductive system, especially scrotal ultrasonography is very important to monitor the breeding potentials and diagnose various testicular affections. Recent advances in Doppler applications have enabled researchers and veterinarians to properly assess the structural and functional aspects of the testis (Araujo and Ginther 2009;Samir et al. 2021;El-Sherbiny et al. 2022a, b). Doppler ultrasonography is a good diagnostic method that provides both anatomical and velocimetric information on blood perfusion to the testis. Adequate blood flow to the testis is very important because it is the main pathway for delivering nutrients, oxygen, regulatory hormones, and other secretory products to and from the testicular tissues (Pozor and McDonnell 2004;Samir et al. 2021). Blood flow also plays a pivotal role in the maintenance of testicular temperature (Junior et al. 2018).
Anatomically, the testicular artery is derived from the aorta. It runs along the inguinal canal and forms numerous irregular loops, which form a conelike structure. Here, the great coiling of the vessels disperses the heat, resulting in a reduction in the working temperature of the testis (Kastelic et al. 1997;Shahat et al. 2020). The degree of coiling of the testicular artery varies among animal species. The coiling of the testicular artery is very high in bulls (up to 130 loops), rams (80 loops), and goats (50 loops) . Hence, obtaining repeatable values of Doppler measures of arterial blood flow of the testis is technically challenging (Pozor and McDonnell 2004), and time-consuming, especially under field conditions, due to the tortuous appearance of the testicular artery at the convoluted part (Almeida et al. 2008), making it difficult to establish the insonation angle. Thus, specialized knowledge and training (anatomy, techniques, interpretations), as well as the implicit need for complementary technologies (for example, real-time B-mode ultrasound), are necessary for the definitive diagnosis of different conditions . Also, the Doppler examination requires the patience and technical skills of the operator as well as the cooperation of the animal, especially when different segments of the testicular artery are targeted for assessment (Trautwein et al. 2019;Samir et al. 2021). Moreover, animal vigorous behavior, especially for big bucks with long horns should be carefully considered. In fact, some animals may experience tremors and fear, which can interfere with the examination. Stressed and/or nervous animals may present tachycardia, which might influence the Doppler waveform morphology (Araujo and Ginther 2009;Trautwein et al. 2019).
In general, sedation is intended to reduce anxiety fear, and distress, and to facilitate the successful performance of diagnostic or therapeutic procedures, providing patient comfort and cooperation. Therefore, sedation of nervous animals may be important to facilitate the scanning in some cases, especially under field conditions (Araujo and Ginther 2009). Xylazine is one of the alpha-2 adrenergic agonists that can produce dose-dependent sedation, analgesia, and muscle relaxation (Naddaf et al. 2014;Celestine Okwudili et al. 2014). Xylazine is exclusively used as a sedative, analgesic, and muscle relaxant in various veterinary medicine practices. However, its effect on testicular blood flow parameters was not investigated in ruminant animals such as goats. Therefore, the present study aimed at investigating the effect of xylazine sedation using the recommended dose in goats (0.05 mg/kg body weight; Abril-Sánchez et al. 2018;Mandour et al. 2020a) on testicular blood flow parameters as measured by color pulsed Doppler ultrasonography and testicular echotexture as assessed by computer software analysis. In addition to testicular blood flow and testicular echotexture, measuring the reproductive hormones such as FSH, LH, inhibin, testosterone, estradiol, and cortisol has a pivotal role in the proper assessment of overall animal fertility. However, there are limited data concerning the effect of xylazine sedation on the peripheral concentrations of reproductive hormones. Therefore, the study aimed to investigate the changes in circulating hormones (FSH, LH, inhibin, testosterone, estradiol, and cortisol) in sedated and non-sedated goats using radioimmunoassay (RIA).

Materials and methods
The present study was performed on male Shiba goats (Capra hircus), a Japanese miniature nonseasonal breeder goat. All procedures in the current study were carried out in accordance with the ethical guidelines of the local committee of the Tokyo University of Agriculture and Technology, Japan, for the use of animals (Ethical approval # 30-78).

Animals and management
Sixteen sexually matured male Shiba goats (Capra hircus), 28.12 ± 1.11 months of age (mean ± SEM, based on birth records and microchip identification), weighing 29.25 ± 1.13 kg (mean ± SEM), and housed in a paddock under natural daylight conditions were used in the current study. Bucks were fed a diet of 1200 g of hay cubes per animal a day. Clean tap water and mineralized salt licks were accessible ad libitum. The goat paddock used belongs to the Laboratory of Veterinary Reproductive Physiology, Veterinary Medicine Department, Tokyo University of Agriculture and Technology, Japan (35.6690° N, 139.4777° E). All bucks were free from any evidence of disease, clinically healthy, and with good libido before the experiment's commencement. Moreover, each buck was exposed to a general examination including the testis and epididymis by ultrasonography to verify the absence of abnormalities in the reproductive tract before the study.

Experimental design
First, each goat was fully scanned for testicular morphometry (testicular size, and echotexture) and blood flow using B-mode, and color Doppler ultrasonography before sedation with the recommended dose of xylazine (0.05 mg/kg body weight, xylazine hydrochloride, Fujita-Pharm, Japan) intramuscular. After administration of the sedative dose (about 10 min; sedation symptoms became clear; Abril-Sánchez et al. 2018), the full scanning was repeated, and all parameters were measured. In this regard, the onset, degree, and duration of sedation were reported. The onset of recumbency, the duration for recovery, and the standing time of bucks were addressed, too. Degree and level of sedation were scored continuously all over the study time on four levels (from zero to three) as previously described (Moolchand et al. 2014): Score (0) for no sedation and the animal was alert and active. Score (1) was light sedation (the animal was standing quietly, staggering a little with its head lowered below shoulders). Score (2) for medium sedation (the animal was drowsy, staggering with its head lowered beyond its knees, and eventually went into sternal recumbence). Score (3) was for deep sedation (the animal dropped its head beyond its knees, staggering, and eventually went into lateral recumbency). In this vein, the procedures after sedation were performed on different days (3-5 days after the pre-sedation procedures) to avoid the influence of animal handling stress during the pre-sedation procedures.

Ultrasonographic examinations
Monitoring the changes in TBF was performed by the same operator using an ultrasound scanner (EUB-7500, Hitachi Medical Corporation, Tokyo, Japan) equipped with a linear multi-frequency array transducer (6-14 MHz; Model EUP-L65; Hitachi Medical Corporation, Tokyo, Japan). Assessment of the TBF in bucks was performed as previously described (Samir et al. 2015(Samir et al. , 2018b. In brief, the bucks were simply secured, the hairs on both sides of the scrotum were removed by shaving, and a copious amount of ultrasonic gel was used on the transducer to facilitate the assessment by ultrasonography. In the present study, we monitored testicular hemodynamics in supratesticular arteries (STA) and marginal testicular arteries (MTA). In brief, after the vascular structures were identified and the largest longitudinal or oblique section of the STA (Fig. 1A), as well as the MTA (Fig. 1B), was observed using B-mode ultrasonography, Doppler assessment of TBF was carried out as previously described (Samir et al. 2015 in goats. After the appearance of the spectral pattern of the STA ( Fig. 2A) and the MTA (Fig. 2B), appended parameters were assessed: peak systolic velocity (VP, cm/sec), end-diastolic velocity (Vd, cm/sec), and the time-averaged mean velocity (Vm, cm/sec). Doppler indices of the blood perfusion within the examined arteries, resistive index (RI = (VP-Vd) / VP), and pulsatility index (PI = (VP -Vd) / mean velocity) were automatically determined. The cross-section area of the examined vessel (CSA) and other parameters that mathematically reflected the cardiac function through the peripheral blood vessel such as heart rate were automatically calculated by the device (three times per goat). All spectral-Doppler settings (gains, focus, brightness, and contrast) were fixed and standardized. The angle between the long axis of the examined vessel and the Doppler beam was less than 60 degrees in the direction of blood flow. The high-pass filter and the Doppler gate were set constant at 50 Hz and 1.5 m, respectively.
Estimating the changes in the testicular volumes (TV/ml) in all animals was performed by the same examiner gently without pressure until the appearance of the mediastinum of the testis. Three longitudinal transverse sections of the testis were scanned, and the testicular length (L), width (W), and height (H) were measured using electronic calipers without the inclusion of the epididymis. The testicular volume was calculated using the following formula: TV (ml) = L × W × H × 0.71 (Paltiel et al. 2002;Samir et al. 2020b).
A cross-section and a longitudinal section of each testis were imaged for further analyses using computer-assisted image analysis software (ImageJ, MD, USA); as described in previous studies (Ahmadi et al. 2012;Brito et al. 2012;Pozor et al. 2017). For the cross-sections, the transducer was perpendicular to the longitudinal axis of the testis. For the longitudinal sections, the transducer was put on the lateral side and parallel to the longitudinal axis of the testis. Ultrasonographic images were retrieved and copied onto the computer and the saved images were assessed using the spot technique. A total of four rectangular-shaped spots (5 mm × 10 mm) were placed on each saved image of homogeneous testicular parenchyma (Fig. 3), excepting artifacts. The pixel intensity (PI) of the testis represents the average pixel values within the selected area of the testis parenchyma based on a reverse gray shades scale (1-255); so number one is representing the black and number 255 is representing the white (Brito et al. 2012;Camela et al. 2019;Samir et al. 2020c). Results from the left and right testes in the current study were averaged for analysis.
In this regard, the experimental procedures were monitored by the third author and visualized by other authors for proper assessment of the standard criteria of the technique including animal handling scores (from 1 to 5; being 5 is the more difficult for the handling of animals during scanning procedures), time (in minutes) required to finish the full scan Fig. 2 Evaluation of the blood flow within the supratesticular artery (A) and marginal testicular artery (B) in goats that appeared as a wave-like display by color-pulsed Doppler ultrasonography per a goat, the attempt of animal escape or the frequency of animal movement during evaluation, and the safety or the calm score for the animal, operator, and the device (due to non-calm bucks; from 1 to 5; being 5 is the calmer during scanning).

Blood sampling and hormonal analysis
Blood samples were drawn (during the scanning procedures in the non-sedated and sedated bucks) from the jugular vein into evacuated heparinized tubes (Venoject II, Terumo, Tokyo, Japan). All samples were withdrawn at a similar time frame (15 min). Plasma was obtained after blood samples were centrifuged at 3200 rpm (600 g) for 15 min at 4 o C, then separated and stored at -20 o C till assessment of concentrations of circulating hormones.

Statistical analysis
The Shapiro-Wilk test was used to assess the normality of data of all variable distributions (Ghasemi and Zahediasl 2012;Mishra et al. 2019). The Paired t-test was used to analyze the significance before and after xylazine administration for parameters with P ˃ 0.05, and data are expressed as Mean ± SEM. For the non-gaussian data which showed a significant Shapiro-Wilk normality test (non-parametric data), the Mann-Whitney Wilcoxon Test was used, and the median and the range values (minimum and maximum values) were considered. In this regard, the studied parameters of testicular hemodynamics and echotexture were normally distributed (P ˃0.05), while some parameters of hormonal measurements and the evaluation technique showed no normal distributions (Supplement Table 1). Therefore, all hormonal and evaluation technique parameters were tested by the Mann-Whitney Wilcoxon Test. Because our data is necessary for clinical application, we expressed all results of hormonal concentrations and evaluation parameters in the form of mean ± SEM for easier comparison and interpretation. All statistical analyses were performed using GraphPad Prism 5 (San Diego, CA, USA). A value of P < 0.05 was considered statistically significant.

Results
The effect of xylazine sedation on parameters of testicular blood flow within the supratesticular and marginal testicular arteries is presented in Table 1. Parameters related to testicular blood perfusion in the examined vessels showed the nonsignificant effect of xylazine sedation. A significant decrease in heart rate was observed in goats after administration of xylazine (105 ± 6 vs. 80 ± 5 bpm; P < 0.05). The CSA of the examined MTA showed significant increases after xylazine sedation (0.053 ± 0.007 cm 2 ) than before xylazine administration (0.034 ± 0.002 cm 2 ). Moreover, the effect of xylazine sedation did not induce significant changes (P ˃ 0.05) in the testicular volume and echotexture parameters of testicular parenchyma as assessed by computerized image analysis software (Table 2). The effect of sedation with xylazine on concentrations of hormones in the present study is presented in Table 3. Cortisol levels were significantly (P ˂ 0.05) lower in bucks after sedation (42.88 ± 6.79 ng/ml) compared with nonsedated ones (94.89 ± 13.74 ng/ml). Testosterone levels were not different within groups (sedated goats: 6.85 ± 1.32 ng/ml versus the non-sedated goats: 9.65 ± 1.24 ng/ml; P ˃ 0.05). Significant (P ˂ 0.05) reductions in circulating E2 were found in sedated bucks compared to the non-sedated ones (sedated bucks; 2.47 ± 0.58 pg/ml versus non-sedated bucks; 8.65 ± 1.79 pg/ml). Concentrations of inhibin, FSH, and LH showed non-significant changes (P ˃ 0.05).
In this study, the onset of sedation was characterized when the sedation score ˃ 0. Firstly, the animal showed decreased head and ear movements then showed a mild head drop (4.55 ± 0.05 min), and progressed to show moderate, then severe head drops, and staggering a little with its head lowered below shoulders). The medium sedation symptoms were noticed at 8.41 ± 0.08 min after injection of xylazine. The duration of the medium sedation and total duration of sedation (referred to as the time elapsed from recumbency to standing) were 25.10 ± 0.95 and 63 ± 1.50 min, respectively. Most bucks showed a score of 2 for sedation at the time of scanning (2.10 ± 0.05). In this regard, the animal handling score (Table 4; mean ± SEM) was significantly lower after sedation with xylazine (1.75 ± 0.11) than before Table 1 Effect of xylazine sedation (before and after xylazine sedation; non-sedated and sedated goats, respectively) on characteristics of Doppler parameters of testicular blood flow (mean ± SEM) in Shiba goats (n = 16) n = The number of bucks that were used during the study (in two different conditions; before and after xylazine sedation) Abbreviations: VP: Peak systolic velocity (cm/s), Vd: End diastolic velocity (cm/s), Vm: Time average mean velocity (cm/s), RI: Resistive index, PI: Pulsatility index, CSA: Cross-sectional area of the examined vessel (cm 2 ) * Represent significant differences (at least at P ˂0.05) between non-sedated and sedated goats 2.00 ± 0.13 5.00 ± 0.00* sedation (3.50 ± 0.38). Also, the required time to perform full scanning of the testis was significantly lower after sedation with xylazine (8.50 ± 0.38 min) than before sedation (25.75 ± 1.14 min). The frequency of animal trials to escape or move during the Doppler scanning was significantly lower in sedated goats (6.50 ± 0.62) compared to the non-sedated ones (18.95 ± 1.19). Also, a high safety score (5.00 ± 0.00) was found, and a low number of assistants (one assistant) was needed for full scanning of the testis after sedation with xylazine than before sedation (2 assistants, safety score of 2.00 ± 0.13).

Discussion
Testicular blood flow plays important role in the physiological functions of the testis. Many literatures reported close relationships between testicular blood perfusion and the potential animal's fertility (Samir et al. 2020c. Under field circumstances, Doppler assessment of testicular hemodynamics requires high caution, and tranquilization may be needed to prevent injuries from kicks and ensure the safety of the examiner, animal, and Doppler device altogether (Araujo and Ginther 2009;Mandour et al. 2021;Samir et al. 2021). The current study is the first that addressed the effect of xylazine sedation on testicular blood flow, testicular volume and echotexture, and the circulating hormones on goats, despite being a good model of ruminants for studying characterization of the blood flow dynamics in previous literatures (Samir et al. 2018b(Samir et al. , b, 2021Mandour et al. 2020bMandour et al. , 2022).
In the current study, no significant changes were reported in the Doppler measures and indices of testicular blood flow. Our results agreed that those reported in the pony and horse stallions (Pozor and McDonnell 2002). An appropriate dose of xylazine was recommended in stallions as it does not induce prominent variations in testicular blood flow (Pozor and McDonnell 2002). However, higher doses of xylazine are not recommended to avoid sedating the horse heavily and to avoid someone getting accidentally kicked (Pozor and McDonnell 2002;Pozor 2007;Samir et al. 2021). Parental administrations of xylazine and ketamine combination in rabbits produced transient vasodilatation at the left common carotid artery and the abdominal aorta. Despite central vasodilatation, bradycardia, and decreases in fractional shortening and average volumetric flow, mean arterial blood pressure did not significantly decrease indicating a well-preserved cardiovascular compensatory mechanism after administration of this combination (Baumgartner et al. 2010). In addition, the present study showed nonsignificant changes in testicular hemodynamics, testis volume, and echotexture. Thus, it would be interesting to extend the clinical uses of xylazine sedation for the full assessment of testicular function under field conditions. Sedation with detomidine (a more potent and rather specific alpha 2-adrenoceptor agonist in the central and peripheral nervous systems than xylazine) in pony mares and xylazine in Holstein heifers did not induce variations in the vascular perfusion in reproductive organs (Araujo and Ginther 2009).
Under field conditions, sedation may be intended to reduce animal distress and facilitate the successful performance of diagnostic or therapeutic procedures. In the present study, the time required to finish the Doppler evaluation of TBF, attempts of animals to escape, and the frequency of animal movement during scanning were low in the sedated goats compared to the non-sedated ones. In addition, a significant decline in the levels of cortisol was observed in the xylazine-sedated group. Similar findings were reported in dogs (Vaisanen et al. 2002) and goats (Aghamiri et al. 2022) after xylazine sedation. Decreased cortisol levels may be attributed to the depression effect of sedation on the CNS and the adrenocortical stimulation caused by emotional stress (Sanhouri et al. 1992;Oyama 1973;Tranquilli et al. 2007).
Cortisol level is directly related to cardiac functions and blood flow since increased cortisol levels could induce increases in heart rate and cardiac output (Kelly et al. 1998;Whitworth et al. 2005;Morris et al. 2016). Oral administrations of cortisol could induce dose-dependent increases in blood pressure (Kelly et al. 1998). In the present study, xylazine sedation induced significant decreases in the levels of cortisol and heart rates but was not associated with significant changes in TBF parameters. In goats, heart rate, cardiac output, and Doppler hemodynamic parameters of the pulmonary artery, aortic and mitral inflows were significantly reduced after sedation with xylazine . Explanations of these findings may be attributable to the vasodilatory effect of xylazine on the testicular artery as evidenced by significant increases in the CSA of the testicular arteries. The testis performs its physiological functions in a semi-hypoxic environment (Bergh et al. 2001;Barros Adwell et al. 2018). Decreased TBF could alter testicular metabolism and oxygen requirements, resulting in defective energy metabolism, ischemia of testicular tissues, and in turn impairment of spermatogenesis (Hsu et al. 1994). The authors claimed that increases in the CSA of the testicular artery may compensate for the decreased heart rates and cardiac output induced by xylazine sedation, and in turn, may keep the blood perfusion to the testis with no prominent changes. The vasodilatory effect of xylazine on common carotid arteries was also reported in a rat model (Chiba and Tsukada 1990). Another explanation, the testis may degrade the xylazine rapidly, and consequently, no significant effects on TBF were found. Recently, Nomura et al. (2022) reported that Dexmedetomidine (DEX), one of the alpha 2 agonists (the same family as xylazine), is metabolized rapidly and did not induce harmful effects on the testis in mice and alter the testosterone levels, despite the existence of its receptors in the testis.
Estradiol is a potent steroid hormone secreted mainly from the Leydig cells of the testis in goats. Interestingly, a significant reduction in the levels of E2 was reported in the sedated goats compared to the non-sedated ones. Up to date, three receptors of E2 (α; ERα and β; Erβ, and the G protein-coupled Estrogen receptor 1; GPER, aka GPR30) were investigated in the cardiac myocytes and the vascular tissues by which E2 induces various protective effects in the cardiovascular system (Knowlton and Lee 2012;Tran 2020). Estrogen prevents apoptosis and necrosis of cardiac and endothelial cells. Estrogen also attenuates pathologic cardiac hypertrophy. Estrogen may have great benefits in aging as an anti-inflammatory agent (Knowlton and Lee 2012). The underlying mechanisms concerned with the decreased levels of E2 in the sedated goats were not fully identified in the present work, but they may be attributable to the regulation of numerous calcium-dependent activities in cardiovascular tissues (Tran 2020). Estrogen exhibits multiple mechanistic roles (regulation of mitochondrial function, cardiac remodeling, cardiac hypertrophy, calcium homeostasis, and titin isoform switches) that affect various aspects of the diastolic function of the heart (Li and Gupte 2017). E2 modulates the expression of various genes (possibly those related to the cAMP-calcium channel pathway) and contributes to sex differences in cardiac contraction and responses to stress. Also, it can confer protection against cardiac stress by non-genomic acute signaling via its receptors (GPR30) (Machuki et al. 2019). Loss of E2 in menopause women may impact heart diastolic function through changes in mitochondrial metabolic function; induction of cardiac remodeling; enhancement of left ventricular hypertrophy; impairment of nitric oxide pathway/role of GPR30; alteration of cellular calcium, and alteration of titin (Li and Gupte 2017).
Ruminants are more sensitive to the effects of xylazine than most other species; goats are considered to be more sensitive to the effects of xylazine than other ruminants' tension (Swindle et al. 2002). Xylazine administration can induce rumen atony with bloat, and decreased cardiac function, including decreased heart rate, decreased cardiac output, right ventricular contractility, and fluctuation of blood pressure and oxygen tension (Wagner et al. 1991;Swindle et al. 2002;Mandour et al. 2020a). Decreased E2 concentrations in the peripheral venous blood in the sedated goats may be attributed to either the decrease of the cardiac function induced by xylazine or to unknown maneuver attempts of the body to restore the cardiac function through withdrawal of E2 from the peripheral circulation to the cardiac tissue. However, the exact mechanism by which the peripheral plasma E2 concentration temporally decreased after xylazine sedation is unknown and a further study, at least at metabolomic levels, may be needed. E2 has its vasodilatory effect on the testicular blood flow as investigated in previous studies (Rosenfeld et al. 2002;Bollwein et al. 2008;El-Sherbiny et al. 2022c), however, the testicular hemodynamics parameters were not significantly reduced in this study.
The effect of different doses of xylazine sedation on the measured parameters was out of the scope of the current study due to the high sensitivity of goats to the xylazine (Swindle et al. 2002). Semen quality was not assessed in the present study under sedation conditions due to the inability of semen collection during sedation by the conventional artificial vagina. However, the beneficial effect of sedation on the quality of the semen collected by electroejaculation was reported in goat bucks by decreasing the stress and the pain response provoked by electroejaculation (Abril-Sánchez et al. 2018). Based on the obtained results, the use of xylazine may be recommended to induce sedation for a full assessment of testicular volume, echotexture, and hemodynamics using B-mode and color-pulsed Doppler ultrasonography in goats under field conditions.

Conclusion
Taken together, xylazine sedation may be practically recommended for the evaluation of TBF in goats because it did not significantly alter velocities parameters and Doppler indices of blood flow within the testicular arteries. There were no effects of xylazine sedation in TV, testicular parenchyma parameters, and in the most hormone evaluated (P ˃ 0.05); however, estradiol and cortisol were significantly reduced after xylazine administration in bucks.