Evaluation of ‘Section‐Ligation‐Release (SLR)’ Technique Devised for Castration in the Stallion

A novel technique [Section‐Ligation‐Release (SLR)] was evaluated for castration in the horse. Clinical traits, serum testosterone concentrations after challenge with human chorionic gonadotrophin (hCG), and histopathological changes of the testicular tissue were assessed. Five stallions, aged 24–48 months, were castrated using SLR technique under general anaesthesia. Both spermatic cords in each stallion were exposed at the scrotal neck by two 5‐cm long incisions, followed by sharp dissection through the parietal vaginal tunic. Both vascular and non‐vascular structures in the cords were triple clamped, transected and ligated. Both testes were left in situ. Serum testosterone concentrations were measured pre‐operatively and at 2 months after castration following IV administration of 1 × 10⁴ IU of hCG. Both testes from each castrate were collected at 2 months for histopathologic examination. SLR castration was successfully achieved. Moderated scrotal and preputial swelling was the only experienced short‐term complication. Serum testosterone concentrations were significantly lower than basal pre‐operative levels at 2 months after castration, and did not respond to hCG. On histopathology, hyalinization of the seminiferous tubules and loss of testicular interstitial tissue were indicative of complete avascular necrosis. This novel primary closure castration technique of stallion is a simple practical method, with minimal post‐operative complications; and could be safely advocated as an alternative to the traditional castration techniques allowing for second intention healing of scrotal wounds.     

Simultaneous presence of a seminoma and a leiomyoma in the testes of a horse

An 18‐year‐old stallion was presented for castration because of insidious, bilateral scrotal enlargement of one year's duration. The left testis was firm, while the right was soft and lobulated; both were larger than normal. Palpation of the scrotum and its contents did not cause the horse to show signs of discomfort. Ultrasonography of scrotal contents revealed abnormal, heterogeneous tissue with ill defined regions of hyper‐ and hypoechogenity throughout both testes. Several hours after admission the horse developed severe signs of colic. On the basis of anamnesis, clinical findings, and results of ultrasonography and transrectal palpation bilateral testicular neoplasia and incarcerated inguinal hernia were tentatively diagnosed. Because the horse's owner did not consent to surgical treatment, the stallion was subjected to euthanasia. Histological and immunohistochemical examination of the testicular tissue collected post mortem revealed a seminoma in the left testis and a leiomyoma in the right testis. The post mortem examination also revealed incarceration of the small intestine in addition to the testicular tumours. To our knowledge, this is the first report of the simultaneous presence of bilateral, yet different testicular tumour types in a stallion.     

Bilateral leiomyoma in the testes of a horse

A 19‐year‐old Hackney pony was referred to a veterinary teaching hospital for further investigation of left‐sided scrotal enlargement. Both testes were normally positioned within the scrotum and there was no pain on palpation. Ultrasonography revealed multiple masses of soft tissue echogenicity, located adjacent to the testicular parenchyma. They were hyperechoic when compared to the testicular parenchyma and affected both testes. Surgical excision was performed by closed castration. Gross examination revealed firm, white, nodular masses of varying size on the surface of both testes. The cut surface of individual masses had a dense, whorling, fibrous and somewhat shiny appearance. The histopathological diagnosis was bilateral, multicentric, well differentiated leiomyoma of the tunica albuginea. The smooth muscle origin was confirmed by immunohistochemical staining with an anti‐human monoclonal antibody reactive to smooth muscle actin. This is the first report of a bilateral, multicentric, leiomyoma in the testes of a horse confirmed by histopathology and immunohistochemistry. This case highlights that neoplasia should be considered as a differential for bilateral testicular enlargement.     

Mesothelioma of the tunica vaginalis testes in a stallion

Scrotal enlargement is a problem in stallions that often leads to poor semen quality. Although there are many causes for scrotal enlargement, testicular neoplasia is often high on the differential list, especially in an aged stallion. This case report describes a stallion with scrotal enlargement caused by a rare neoplasia located in the tunica vaginalis, and not in the testicular parenchyma. Diagnosis of mesothelioma was made following hemicastration. Prognosis in other species is variable, but this stallion returned to his successful breeding career following treatment and has remained healthy one year following the diagnosis.     

Unilateral testicular mastocytoma in a Peruvian Paso stallion

A 12‐year‐old Peruvian Paso stallion was examined for scrotal swelling and unilateral testicular enlargement of 4–6 weeks duration. Physical examination and ultrasonography of the scrotum revealed an enlarged, nonpainful right testis with a well encapsulated mass at the cranial‐medial aspect containing echodense flocculent material. Unilateral castration was performed and the testis, spermatic cord and vaginal tunic were submitted for histological examination, which revealed a mastocytoma with accompanying evidence of malignancy. Short‐term follow‐up examination did not reveal any evidence of abdominal metastasis and the stallion has since successfully achieved pregnancy in a small number of mares. Although considered rare, mast cell neoplasia should be considered as a differential diagnosis when unilateral testicular enlargement is encountered.     

Ultrasonographic and morphological sequelae to repeated testicular biopsies in stallions in relation to the lateral branching of the testicular artery

The objectives of this study were to investigate the sequelae to repeated testicular biopsies in stallions and to determine if arterial injuries can be prevented. This study was part of a larger project focused on the antispermatogenic effects of an oral contraceptive compound, RTI‐4587‐073(l), which was given to 3 mature Miniature horse stallions, while another 3 received a placebo treatment. Testicular biopsies were taken once before treatment and 3 times after treatment. They were obtained from alternating testes, 2 procedures per testis, 2 samples each time, using a 18 gauge split‐needle core biopsy instrument (penetration depth: 22 mm). Colour Doppler ultrasonography was performed prior to the procedure to detect and thus avoid lateral branches of the testicular artery. Testicular parenchyma was evaluated ultrasonographically just before, and 2–6 h, 3 days and weekly after the biopsies were obtained. Changes in testicular volumes and semen parameters were monitored. All stallions were then castrated and the testes were evaluated for any gross pathology. There was no major scrotal swelling or gross haemorrhage after the procedures. Only mild, focal lesions were found in the testicular parenchyma 3 and 7 days after taking the biopsies. Three lateral branches of the testicular arteries were punctured, but there was no evidence of significant bleeding or other complications associated with these injuries. We conclude that repeated testicular biopsies may be taken from stallions without causing major complications, regardless of a presence or absence of the lateral branches of the testicular artery. Furthermore, we conclude that using colour Doppler ultrasonography to detect the lateral branches of the testicular arteries is unreliable; however, puncturing these vessels during a biopsy procedure does not necessarily result in significant haemorrhage.     

Ultrasonographic and quantitative histologic assessment of sequelae to testicular biopsy in stallions.

A sample of testicular parenchymal tissue, approximately 2 x 7 x 7 mm, was aseptically removed from 1 testis in each of 9 stallions on day 0. Slight to moderate hemorrhage from the tunica albuginea was observed in 8 stallions, but bleeding from the parenchyma was detected in only 2 stallions. Stallions were castrated 27 days later. Normal development of granulation tissue was evident at the biopsy site, but hematomas were not observed. In situ measurement of the widths of the right and left testes, total scrotal width, and evaluation of testicular echogenicity during ultrasonography were variables used to monitor changes in the testicular parenchyma from 14 days before biopsy through 27 days after biopsy. The control testis was consistently larger than the biopsied testis, except for day 3. Ultrasonography revealed signs of a localized change in the parenchyma of the biopsied testis in 4 stallions, but each lesion decreased in size by day 27. Tissues removed during biopsy enabled an excellent appraisal of spermatogenesis at that time. Detailed examinations of seminiferous tubules in the testes were performed to assess for damage to testicular function. At castration, samples were taken from 6 sites in each testis. Quantitative histologic evaluations of testicular tissues revealed low numbers of spherical spermatids and pachytene spermatocytes in biopsied testes, compared with control testes. It was concluded that there was a transitory increase in degeneration of preleptotene spermatocytes and B spermatogonia at the time of biopsy. A mild inflammatory response at the biopsy site in some testes was evidenced by an increased number of leukocytes at the biopsy site and at a dorsal site.(ABSTRACT TRUNCATED AT 250 WORDS)     

Localization of aromatase in Equine Leydig cells

Stallion testes secrete large amounts of estrogens, but the cellular location of the enzyme that converts androgens to estrogens, cytochrome P₄₅₀ aromatase, has not been determined. The goal of the present study was to immunocytochemically localize stallion testicular aromatase using a polyclonal antibody generated against human placental cytochrome P₄₅₀ aromatase. Testes were obtained from 12 stallions from 2 to 23 years of age, during both the breeding and non-breeding seasons. Immunoreactivity was confined to the Leydig cells in all testes examined. No immunostaining was observed in the Sertoli or germ cells. Heterogeneity in the level of immunostaining among individual Leydig cells was observed. The results of this study indicate that in postpubertal, adult, and aged stallions, testicular aromatase is located in Leydig cells.     

Lateral Branches of the Testicular Artery Affect Testicular Shape in Adult Stallions

The objective of this study was to investigate the arterial patterns of the stallion testis in relation to testicular shape. Two hundred and fifty-one stallion testes were evaluated for the presence of the lateral branches of the testicular artery. Seven specimens had their testicular arteries filled with latex milk, fixed in 70% alcohol, and dissected. Two hundred six specimens (82%) had a single testicular artery and no lateral branches; 39 testes (16%) had one lateral branch of the testicular artery; and six testes (2%) had two lateral branches of the testicular artery each. The lateral branches of the testicular artery obtained from the adult stallions, more than 5 years old, were associated with distinct lateral bulging, giving them a pear-like shape, whereas similar vascular pattern in young colts, less than 1 year old, did not cause similar shape change. Five distinct patterns of the branching of the testicular artery were determined. We concluded that the lateral branches of the testicular artery are present in approximately 20% of stallion testes. This anatomic pattern is associated with a lateral bulge that develops slowly over several years and is associated with a change in testicular shape from an ellipsoid in colts to a pear-like shape in adult stallions.     

Acute cortisol responses of lambs to castration using a rubber ring and/or a castration clamp with or without local anaesthetic

Changes in plasma cortisol concentrations during the first 4 hours after castration of 6-week-old lambs by one of four methods were measured. The methods were application of a rubber ring above the testes, application of a ring to shorten the scrotum below the testes, use of a castration clamp plus a ring, and use of a castration clamp alone. The efficacy of local anaesthetic in reducing or abolishing the cortisol responses to castration by all these methods except short scrotum was assessed. Local anaesthetic was injected into the neck of the scrotum, both spermatic cords, the scrotal neck plus spermatic cords, or into both testes. The combined clamp plus ring method was used to test whether or not clamp damage to afferent nerves from the testes would reduce the cortisol response to ring castration. The short scrotum method elicited a significantly lower cortisol response than that caused by ring castration. Injection of local anaesthetic into both spermatic cords marginally reduced the cortisol response to ring castration, but the response was virtually abolished by prior scrotal neck, or scrotal neck plus spermatic cords, or intra-testicular local anaesthetic injections. The clamp plus ring method, where each spermatic cord and the associated scrotal tissue were crushed separately for 1, 5 or 10 seconds with no overlap between the two crush lines, did not elicit lower cortisol responses than the ring-only method. Local anaesthetic injected into the scrotal neck virtually abolished, and spermatic cord injections markedly reduced, the cortisol responses to combined clamp plus ring castration. The IO-second clamp application caused a more protracted cortisol response than did ring-only castration, whereas the cortisol responses to 1-second clamp application and to ring-only castration were similar. Local anaesthetic injected into the scrotal neck or spermatic cords did not affect significantly the cortisol response to the IO-second clamp application. The following conclusions were drawn from this work: the testes as well as the scrotum were sources of noxious sensory input after ring application; the clamp plus ring method used here was ineffective in reducing the pain-induced distress (as indicated by cortisol concentrations) caused by ring-only castration; injection of local anaesthetic into the scrotal neck or into the testes prior to ring application blocked most noxious sensory input from both the scrotum and the testes; and on the basis of the present cortisol responses the 10-second clamp applications method could not be recommended in reference to the ring-only method, but the l-second clamp application method might be equally acceptable for castrating 6-week-old-lambs. Of the methods examined, injections of local anaesthetic into the scrotal neck or both testes were the most effective in reducing the pain-induced distress caused by ring-only castration.     

Recurrent torsion of the spermatic cord and scrotal testis in a stallion

A stallion was twice referred for evaluation of scrotal swelling and signs of pain. The first admission followed a 3-year period of recurrent signs of left-sided scrotal pain and swelling. After the removal of the left testis because of testicular torsion, the stallion was returned to service. The conception rate was 82% for the next breeding season. Two years after initial surgery, the stallion again was evaluated because of acute signs of right-sided scrotal pain and swelling. Right-sided testicular torsion was detected and corrected, and the testis was sutured in place. The stallion's conception rate for the following breeding season was greater than 90%.     

Immunohistochemical expression of dogTERT in canine testicular tumours in relation to PCNA,ki67 and p53 expression.

The objective of the study was to determine the immunohistochemical expression of canine TERT in canine testicular tumours comparing two different antibodies for TERT, and to correlate them with well established markers specific to dividing cells such as PCNA and ki67, and with expression of the p53 tumour suppressor gene. The study included 36 cases of canine testicular tumours, which were categorized as 12 Sertoli Cell Tumours (SCT), 20 seminomas, 3 interstitial cell tumours and 1 mixed germ cell-sex cord stromal tumour (MT). Two antibodies for hTERT were examined; a highly specific TERT antibody, RCK-hTERT, was evaluated for the first time. Immunodetection of RCK-hTERT was observed in 31% of tumours examined (6/20 Seminomas, 4/12 SCT, 1/3 interstitial cell tumour and 0/1 mixed germ cell-sex cord stromal tumour), while the NCL-hTERT in 67% of them (15/20 Seminomas, 6/12 SCT, 3/3 interstitial cell tumour and 0/1 ΜΤ). PCNA immunoreactivity was detected in all cases. Regarding ki67, 3 SCT, 12 seminomas and all interstitial cell tumours showed clear immunoreaction. p53 immunoreactivity was detected in 6 SCT, 15 seminomas and all interstitial cell tumours. The immunohistochemical expression of both TERT antibodies are discussed and compared in order to clarify their potential usefulness in canine testicular malignancies in relation to the expression of well known cell cycle markers. Our results indicate that TERT and PCNA are useful proliferation markers but not helpful to evaluate prognosis. Instead of that ki67 and p53 could be used for predicting aggressiveness in this group of tumours     

The complex blood supply to the equine testis as a cause of failure in laparoscopic castration

REASONS FOR PERFORMING STUDY: Intra-abdominal ligation/ transection of the spermatic cord may result in necrosis of the testis; castration of abdominal cryptorchids via laparoscopy has therefore become common. Notwithstanding some adaptations of the technique, a small percentage of operations fail, prompting research into the anatomical background and clinical relevance of the procedure. HYPOTHESIS: That an alternate blood supply may prevent complete necrosis of the testis after spermatic cord transection. OBJECTIVE: To establish the prevalence of the problem in normal and cryptorchid stallions. METHODS: In a preliminary study, the spermatic cords of 8 normal stallions were ligated and transected at different sites and in various manners. Five weeks later the testes were removed and the vitality of both the testes and epididymes was evaluated. In a prospective clinical trial, intra-abdominal spermatic cord transection was performed in 241 cryptorchid and normal stallions. In cases of surgical failure, the testes were removed and histology performed. RESULTS: Examination of the specimen removed from the 8 animals of the preliminary study revealed that all epididymes were completely or largely spared. All except one testis were completely necrotic. In the patients that underwent surgery all abdominally retained testes (n = 123) were necrotic, while 5 out of 88 inguinally retained and 8 out of 236 normally descended testes had partially survived. The pattern of survival differed between inguinally retained and normally descended testes. The epididymes of these 13 horses were (largely) vital. The (partial) survival of the epididymes and inguinally retained testes was ascribed to an alternate blood supply via anastomosing vessels derived from the cremasteric artery. A tributary from the external pudendal artery was considered responsible for the partial survival of normally descended testes. CONCLUSIONS AND POTENTIAL RELEVANCE: After intra-abdominal transection of the entire spermatic cord, 5.6% of inguinally retained and 3.4% of normally descended testes failed to become completely necrotic, as a result of an alternate blood supply via the cremasteric and/or external pudendal artery. Therefore, laparoscopic castration without orchidectomy cannot be recommended as a trustworthy method for castration of inguinal cryptorchids and normal stallions.     

Clinical observations on changes in concentrations of hormones in plasma of two stallions with thermally-induced testicular degeneration

To investigate effects of thermally-induced testicular degeneration on hormonal and seminal parameters in stallions, the scrotum was insulated for 36 hours in two mature (5-year-old mixed breed and 11-year-old Throughbred) stallions. Semen was collected daily for 10 days (DSO) prior to, and at intervals after, scrotal insulation. When DSO determinations were not being made, semen was collected 3 times weekly. Jugular blood samples were collected at 15-minute intervals for 6 hours from each stallion prior to, and at intervals after, scrotal insulation. A mouse interstitial cell testosterone assay was modified to quantify biologic activity of equine luteinizing hormone (BLH) in plasma samples. Immunoactive luteinizing hormone (ILH) and testosterone (T) concentrations were determined in plasma samples by routine RIA procedures. Percentages of progressively motile and morphologically normal spermatozoa began to decrease by 1 to 2 weeks postinsulation, reached nadir values at 3 to 3-1/2 weeks postinsulation, and returned to preinsulation values by 7 weeks postinsulation. Total number of spermatozoa and total number of progressively motile, morphologically normal spermatozoa in ejaculates at DSO returned to normal by 8 weeks postinsulation in stallion 2 and 12 weeks postinsulation in stallion 1. Concentrations of BLH and ILH increased, and while T concentrations decreased, immediately postinsulation. The increase in ILH concentrations was greater than the increase in BLH concentrations, resulting in a decrease in the BLH:ILH (B:I) ratio. Following the peak in LH secretion immediately postinsulation, LH concentrations gradually decreased while T concentrations increased. The B:I ratio was elevated from 1 to 13 weeks postinsulation compared to immediately postinsulation. In addition to changes in spermatozoal quality in ejaculates, stallion response to scrotal insulation included increased secretion of luteinizing hormone and impaired Leydig cell function (as determined by reduced testosterone concentration in circulating plasma). The proportion of biologically active LH secreted in response to thermal testicular injury increased during the recovery phase.     

ULTRASOUND APPEARANCE OF AN EQUINE TESTICULAR SEMINOMA

A 16-year-old thoroughbred stallion developed sudden swelling of the left testicle. The stallion had previously been regarded as a unilateral cryptorchid. Ultrasound examination of the left testicle revealed a diffusely heterogeneous parenchyma. The testicle was diffusely hypoechoic with ill defined regions of hyperechogenicity giving the appearance of hypoechoic nodules throughout the testicular parenchyma. No normal testicular tissue was identifiable. An echogenic band, representing a pseudocapsule could be seen surrounding the testicle. Histopathologic diagnosis a seminoma.     

Unsuccessful laparoscopic castration in a cryptorchid Frisian stallion

A 2-year-old unilateral inguinal cryptorchid Frisian stallion was castrated by bilateral laparoscopic intra-abdominal spermatic cord transection. Because blood testosterone levels were still high on postoperative day 7, both testicles were removed using an open approach. Pathology revealed the presence of vital Leydig-cells in both testes. Failure of the laparoscopic castration in this horse was attributed to an alternate blood supply to the testes by vessels derived from the cremaster and/or external pudendal artery.     

Unilateral periorchitis with a secondary peritonitis in a Standardbred stallion

A 6‐year‐old Standardbred stallion presented for evaluation of progressive diffuse scrotal swelling of 5 days' duration. Physical examination was within normal limits apart from pitting ventral oedema and severely enlarged fluid filled scrotum. Rectal examination did not reveal any abnormalities in the palpable intestinal tract, spleen, kidneys or internal inguinal rings. Testicular ultrasound examination showed evidence of abnormal right testicular parenchyma that was displaced proximally by a heteroechoic region of possible abscessation. The left testis was surrounded by a large amount of hypoechoic fluid. Abdominocentesis was performed and was indicative of peritonitis. Broad‐spectrum antimicrobials and analgesics were administered preoperatively and a bilateral open orchidectomy with closure of the external inguinal ring in addition to scrotal ablation was performed. Post operative peritoneal lavage was performed once a day for 3 days. There were no complications associated with recovery or within the immediate post operative period. The horse was released to the care of his owners 5 days following surgery and has returned to his previous racing performance level.     

Testicular torsions in veterinary medicine

The purpose of this review is to provide a comprehensive comparison of spermatic cord torsion in domestic animals. Spermatic cord torsion leads to occlusion of testicular blood flow resulting in ischemia and tissue hypoxia. Spermatic cord torsion has been reported in all domestic mammals but dogs and horses are overrepresented. Abdominal pain (colic), anorexia, vomiting, lameness, and stiff gait are the most common clinical signs reported. The condition may be asymptomatic in cases of a low degree of spermatic cord torsion. In dogs, spermatic cord torsion is most commonly reported in undescended testes, which in some cases are neoplastic. However, in horses, spermatic cord torsion occurs more commonly in scrotal testes. Surgical treatment for spermatic cord torsion depends upon the degree and duration of torsion. If the affected testis is located within the scrotum and determined to still be viable, detorsion with orchidopexy can be performed. Orchiopexy of the unaffected scrotal testis is also recommended in stallions. If the affected testis cannot be salvaged, unilateral or bilateral orchidectomy is recommended. In all cases of spermatic cord torsion of an undescended testis, orchidectomy is recommended. Veterinarians should be aware of the clinical signs and treatment options for spermatic cord torsion in domestic mammals.

Graphical abstract

     

Effects of Intratesticular Injection of 70% Glycerin on Stallions

The removal of endogenous germ cells of recipient stallions is a key step to produce donor germ cell-derived sperm using the germ cell transplantation technique. Six Thoroughbred stallions were divided into a treatment (n = 3) and a control group (n = 3), and 70% glycerin (1, 2, 3-trihydroxypropane, 40 mL per testis) or phosphate-buffered saline, respectively, was locally injected into testes. General semen evaluation, libido, and testicular volume were performed weekly from 3 weeks before to 10 weeks after treatment. The number of round germ cells in the ejaculate was counted using a hemocytometer. The hematoxylin and eosin staining was performed on the cross sections of testicular tissue obtained 11th week of treatment. Plasma testosterone levels in blood collected weekly were measured using a colorimetric competitive enzyme immunoassay kit. The sperm number was significantly lower than that of the control group at 5 and 10 weeks after glycerin injection. No differences in the status of spermatogenesis in the cross sections of seminiferous tubules and testicular volume were found between the two groups. The 70% glycerin-treated stallions had reduced total and progressively motile sperm and exhibited a significantly higher population of round germ cells in the ejaculate. Testosterone levels, testicular volumes, and libido of stallions were not significantly different between the groups. In conclusion, although intratesticular injection of 70% glycerin may have caused disassociation of some germ cells in the seminiferous tubules for several weeks, it did not significantly ablate germ cells in the tubules at 11 week in stallions.     

Effects of Hemicastration on Testes and Testosterone Concentration in Stallions

The endocrine system is critical to the maintenance of testicular function. The homeostasis of sex hormone levels is orchestrated by positive and negative feedback systems controlled by the hypothalamic-pituitary-gonadal axis. This study investigated the long-term effects of hemicastration on testicular size and function in stallions. Four Thoroughbred stallions, 4–6 years of age, were included in this study. Several parameters, including testicular weight and volume, plasma testosterone concentrations, VASA-positive germ cell populations and cross-sectional areas of the seminiferous tubules were compared in stallions that underwent two hemicastrations, approximately 11 months apart. The weights and volumes of testes harvested at the second hemicastration were significantly higher than those of testes collected at the first hemicastration. However, VASA-positive germ cell populations and the cross-sectional areas of seminiferous tubules were not significantly different between testes harvested at the first and second hemicastrations. Similarly, plasma testosterone concentrations measured weekly for 3 weeks before the first hemicastration, 3 weeks after the first hemicastration, and 3 weeks before the second hemicastration were not significantly different. Our results suggest that hemicastration results in compensatory enlargement of the remaining testis and compensatory steroidogenesis to maintain normal reproductive function in stallions.