1 CONTACT Carlos Pinto cpinto@lsu.edu © 2023 The Author(s). This is an Open Access article distributed under the terms of the Creative Commons Attribution-NonCommercial 4.0 International License (http:// creativecommons.org/licenses/by-nc/4.0/), permitting all noncommercial use, distribution, and reproduction in any medium, provided the original work is properly cited. Citation line: Clinical Theriogenology 2023, 15, 9437, http://dx.doi.org/10.58292/CT.v15.9437 Case Report Canine Sertoli cell tumor: anti-Müllerian hormone, inhibin B, and estrone sulphate Fiona Herzog,a Daniella Adams,a Alissa St. Blanc,a Jeongha Lee,b Ingeborg Langohr,b Carlos Pinto,a aDepartment of Veterinary Clinical Sciences, bDepartment of Pathobiological Sciences and Louisiana Animal Disease Diagnostic Laboratory, Louisiana State University School of Veterinary Medicine, Baton Rouge, LA, USA Abstract A unilaterally castrated male boxer was referred for chronic generalized alopecia and pruritus. Physical examination revealed sym- metrical alopecia, pendulous prepuce, lichenification of the scrotum, and enlargement of mammary papillae. Penile/preputial cytology revealed superficial epithelial cells. Transabdominal ultrasonographic examination revealed a globoid mass with heterog- enous echogenicity in the left caudal abdomen. The presumptive diagnosis was Sertoli cell tumor (SCT) associated with cryptorchi- dism. Exploratory laparotomy and histology of the removed mass confirmed the diagnosis. Three weeks after surgery, serum anti-Müllerian hormone (AMH) concentrations decreased from 8,435 to 56 ng/ml and inhibin B decreased from 805 to < 6 pg/ml. Two months after surgery dermatoses subsided and there was substantial regression of enlarged nipples. This report highlights the diagnostic value of practical procedures (penile/preputial cytology, transabdominal ultrasonography, and measurement of serum AMH and inhibin B concentrations) to aid in the diagnosis of cryptorchidism and SCT, especially in patients with generalized skin conditions. Keywords: Cryptorchidism, feminization, paraneoplastic syndrome Background Canine Sertoli cell tumor (SCT) is the most common testicu- lar neoplasm associated with feminization syndromes. The prevalence of feminization in cases of SCT has been reported as 241 and 39%,2 with an increased frequency of the syndrome occurring in cryptorchid testes.2 Clinical signs of feminization are consequent to hyperestrogenism associated with a secre- tory tumor. These include bilateral symmetrical alopecia of the trunk and flanks, hyperpigmentation of inguinal skin, gynecomastia, pendulous prepuce, squamous metaplasia of the prostate, and attraction by male dogs. Preputial cytology is a useful diagnostic aid in cases of SCT to determine the effects of estrogens on preputial epithelial cells; a bioassay for hyper- estrogenism particularly, for dogs with feminizing signs. Additional methods of diagnosis include imaging, explor- atory surgery, and histology. Limited studies have evaluated the endocrine characteristics of canine SCT. Serum estradiol concentrations had variable elevation,3–6 whereas inhibin con- centrations increased in SCT dogs compared to controls.3,5 Serum anti-Müllerian hormone (AMH) concentrations were determined in patients with testicular and other tumors.6 These findings suggested that canine SCTs secrete several hormones that have diagnostic potential. This report describes a case of canine SCT with feminization syndrome and evalua- tion of serum AMH, inhibin B, and estrone sulphate concen- trations before and after tumor removal. Case presentation A 6-year unilaterally castrated (at 6 months of age) male boxer was presented with a history of chronic alopecia and pruritus. Approximately 18 months after castration, the patient devel- oped dermatoses and was treated for presumed atopic derma- titis for several years until referral. At presentation, the patient’s dermatologic lesions included diffuse alopecia, moderate to severe lichenification and scal- ing along the sternum, axillary region, and on medial thighs (bilateral). The scrotal skin had lichenification and edema, and the prepuce was moderately pendulous and edematous. Mammary papillae were enlarged, elongated, and mildly edematous (Figures 1 and 2). The owner reported that changes to the prepuce and mammary papillae had developed concur- rent with signs of alopecia. The patient was receiving 6 mailto:cpinto@lsu.edu http://creativecommons.org/licenses/by-nc/4.0/ http://creativecommons.org/licenses/by-nc/4.0/ http://dx.doi.org/10.58292/CT.v15.9437 2 Citation line: Clinical Theriogenology 2023, 15, 9437, http://dx.doi.org/10.58292/CT.v15.9437 monthly injections of lokivetmab (a monoclonal antibody that acts against interleukin 31) for suspected atopic dermati- tis. Preputial cytology revealed superficial epithelial cells. Transabdominal ultrasonography revealed an oval to globoid mass (4.2 × 3.3 cm) with irregular contour (suspected left tes- tis), located ventro-cranially and slightly left to the urinary bladder. The mass appeared moderately cystic and heteroge- nous in echogenicity, with no distinct mediastinum testis (Figure 3). Mild to moderate iliac lymphadenopathy and splenic nodules were observed. Prostate measurements (35 × 32 × 40 mm) were within normal parameters for an intact dog of the patient’s size and age.7,8 Fine needle aspirates of the left medal iliac lymph node and spleen were consistent with reactive lymphoid hyperplasia and splenic nodular hyperplasia with low-grade extramedul- lary hematopoiesis, respectively. Thoracic radiographs had no evidence of pulmonary metastases. Complete blood cell count and serum biochemistry revealed no abnormal findings. Treatment An exploratory laparotomy was performed. The suspected retained left testis was lateral and adjacent to the left aspect of the urinary bladder. The left testis and a section of the sper- matic cord with which it was associated, and the enlarged left medial iliac lymph node were surgically removed. Tissues were submitted for histological evaluation. Pathology The left testis had a multinodular appearance and measured 5.0 × 4.0 × 3.5 cm (Figure 4). The cut surface had a tan, soft, Figure 3. Oblique ultrasonographic image of the irregular mass (33.2 mm between calipers A and 41.8 mm between cal- ipers B) of suspected retained left testis (note moderate cystic and heterogenous echogenicity appearance) Figure 1. Sternum, mammary gland, and prepuce (note dif- fuse alopecia across sternum, enlargement of mammary papillae, and pendulous prepuce) Figure 2. Mammary gland and prepuce (note diffuse ventral alopecia, enlarged mammary papillae, and pendulous prepuce) http://dx.doi.org/10.58292/CT.v15.9437 Citation line: Clinical Theriogenology 2023, 15, 9437, http://dx.doi.org/10.58292/CT.v15.9437 3 multinodular mass with multiple cysts containing brown fluid. Microscopic examination of the abdominal mass con- firmed its testicular origin. Structures identified included sem- iniferous tubules, epididymis, and pampiniform plexus. The testis appeared enlarged and partially replaced by a neoplastic mass consistent with a SCT of diffuse growth pattern (Figure 5a). The neoplasm was partially encapsulated, infiltrative, multi- lobulated, composed of polygonal to elongated cells (Figure 5b) forming variably sized, coalescing lobules separated by a moderate amount of fibrous stroma and palisading along the connective tissue trabeculae. Neoplastic cells had distinct cell borders, eosinophilic to amphophilic, finely granular or clear vacuolated cytoplasm, and round to oval nuclei with finely stippled chromatin and a variably distinct nucleolus. Mild anisocytosis and anisokaryosis were present, with a mitotic count of 15 per 2.37 mm2 (equivalent to 10 FN22/400X fields or 10 high-power fields) (Figure 5d). Frequent neoplastic cells within blood vessels (tumor emboli) were also noted, includ- ing a small cluster of neoplastic cells in the pampiniform plexus (Figure 5c). Seminiferous tubules that remained at the periphery of the neoplasm were small and devoid of germ cells, denoting marked atrophy (Figure 5d) and the epididy- mis was similarly observed that was devoid of sperm. No evidence of metastasis was detected in the left medial iliac lymph node. Endocrinology Serum samples were sent to UC Davis Endocrinology Laboratory for AMH, inhibin B, and estrone sulphate analy- sis by Enzyme-Linked Immunosorbent Assay (ELISA). Serum was collected prior to and 3 weeks after surgery. Serum AMH concentrations decreased from 8,435 to 56 ng/ml after tumor removal (reference interval reported as < 0.15 ng/ml for castrated dogs; Ansh Labs, Webster Texas). Serum inhibin B concentrations similarly decreased from 807 to < 6 pg/ml. Estrone sulphate concentrations were 1.5 ng/ml before sur- gery and 1.3 ng/ml after surgery (reference ranges for estrone sulphate and inhibin B were not reported by the laboratory). Outcome Dermatoses resolved 6–8 weeks after surgery. The enlargement of the mammary papillae was largely resolved by 6 months after surgery. Cranial thoracic mammary papillae were still mildly enlarged; however, the remaining papillae had returned to normal size. The patient’s signs of pruritus were satisfacto- rily controlled with biannual injections of lokivetmab. Consultation with the oncology service for tumor surveillance was recommended 3 months after tumor removal but was declined by the owner. Discussion The patient was presented with a history of chronic alope- cia that poorly responded to long-term treatment for aller- gic dermatitis. An estrogen-secreting SCT was the cause of the patient’s hair loss. Hyperestrogenism due to exogenous or endogenous sources of estrogen is a known cause of non- inflammatory alopecia.9 Clinical signs of alopecia associ- ated with hyperestrogenism are derived from the binding of estrogen-to-estrogen receptor α that is involved in the regu- lation of hair follicle cycle. This binding alters the ana- gen-telogen phase transition of the hair follicle cycle by inducing premature catagen (regression stage) and pro- longing telogen (resting phase).10 This results in a failure of hair growth that can mimic inflammatory and other nonin- flammatory causes of alopecia. Additional signs of femini- zation, including elongation of the mammary papillae and  pendulous prepuce during clinical examination, prompted assessment for potential exogenous or endoge- nous sources of estrogen. This highlighted the importance of a thorough and problem-based approach to the clini- cal investigation of alopecia in male dogs. The persistence of mild pruritus after resolution of alopecia suggested that an unrelated source of inflammatory dermatitis was possible. Superficial epithelial cells comprised the dominant cell type identified on preputial cytology, consistent with hyperestro- genism. Preputial cytology has previously been demonstrated to be a useful investigative tool in cases of SCT, in which the presence of > 20% superficial epithelial cells, as a predictor of elevated serum estradiol concentrations, had a sensitivity and specificity of 80 and 90%, respectively.11 In addition to prepu- tial cytology, abdominal ultrasonography was an important diagnostic modality employed to determine the cause of femi- nization in the current patient. Abdominal ultrasonography permitted identification and localization of the retained testis, facilitating a rapid diagnosis and preparation for surgical removal. Anti-Müllerian hormone AMH is a glycoprotein hormone that belongs to the trans- forming growth factor (TGF) β-family.12 Secretion of AMH from Sertoli cells is most pronounced during fetal Figure 4. Photograph of retained left testis (note multinodu- lar appearance and irregular contour) and pampiniform plexus to its right http://dx.doi.org/10.58292/CT.v15.9437 4 Citation line: Clinical Theriogenology 2023, 15, 9437, http://dx.doi.org/10.58292/CT.v15.9437 development and prior to puberty. In male fetus, AMH sig- nals Mullerian duct regression, preventing formation of uter- ine tubes, uterus, and cranial vagina.13 AMH may have a role in regulating Leydig cell proliferation, function, and testos- terone production.14 During fetal development and prior to puberty, follicle-stimulating hormone (FSH) promoted the production of AMH whereas gonadal testosterone had an inhibitory effect on AMH secretion after puberty onset.15 However, the basal expression of AMH throughout life is independent of gonadotropins.16 AMH has been a useful predictor for the presence of testicular tissue in dogs,17,18 horses19 and calves20 for scrotal and cryptor- chid testes. Limited studies have also investigated its value as a clinical biomarker for canine SCT. Immunohistochemical analysis of 24 SCT expressed AMH.21 In the same study, the Sertoli cells of unaffected fetuses and pups < 45 days also expressed AMH whereas the Sertoli cells of older pups and adult dogs did not. The contrast in AMH expression between normal adult and SCT testes may attest to the diagnostic potential of AMH in canine SCT. Serum AMH concentrations in dogs with SCTs were > 22 ng/ml compared to control dogs that returned to normal concentrations (< 10 ng/ml).6 In this study, concentrations of serum AMH in CSCT patients were significantly elevated compared to dogs in both control and other tumor groups. Serum AMH concentration declined precipitously after sur- gery. A similar trend was observed22 where a patient that was investigated for nonpruritic alopecia had markedly elevated serum AMH concentrations compared to 2 intact control dogs. A SCT affected cryptorchid testis was identified, and 3 months following surgical removal, serum AMH concentra- tions declined in this patient to concentrations similar to 2 castrated control dogs. Serum AMH concentrations after surgery were 56 ng/ml. Serum AMH concentrations reference ranges (Ansh Labs, Webster, Texas) for intact and castrated male dogs are 0.2–73.4 ng/ml and < 0.15 ng/ml, respectively. In this patient, AMH concentrations therefore did not decline to baseline concen- trations 3 weeks after surgery. There are no reports on the half- life of AMH in dogs, although a relatively prolonged half-life of 1.5 days has been described in stallions.19 Persistence of AMH above baseline concentrations 3 weeks after surgical removal of the SCT may reflect a similarly long half-life in Figure 5. Representative photomicrographs of histology of cryptorchid left testis. (a) Sertoli cell tumor compressing the markedly atrophied testicular parenchyma; bar = 1 mm. (b) Polygonal to elongated neoplastic cells palisading along the connective tissue trabeculae. A mitotic figure is in the center (arrow); bar = 50 µm. (c) Small clusters of tumor emboli (arrows) present within a vein in the pampiniform plexus; bar = 100 µm. (d) Atrophic testicular parenchyma with Sertoli cells in shrunken seminiferous tubules devoid of germ cells; bar = 200 µm. http://dx.doi.org/10.58292/CT.v15.9437 Citation line: Clinical Theriogenology 2023, 15, 9437, http://dx.doi.org/10.58292/CT.v15.9437 5 dogs, the marked elevation in serum AMH prior to surgery, or the presence of a secondary tumor. Inhibin B Inhibin is a glycoprotein hormone that contains an α and 1 of 2 possible β subunits designated βA (inhibin A) or βB (inhibin B).23 Inhibin B is the predominant isoform in the adult male of several species including boar,24 stallion,25 rat,26 and human.27 Inhibin exerts a regulatory role on FSH secretion from the anterior pituitary gland. Production of inhibin is stimulated by FSH, whereas inhibin has a conversely inhibi- tory effect on FSH release, completing a negative feedback loop.28 The principal source of inhibin has historically been consid- ered to be Sertoli cells.28 However, inhibin subunits were expressed in Leydig or germ cells and the cellular source of inhibin varied with species and changed during transitions from fetal, neonatal, and adult life.29–33 Inhibin α expression was only detected in Sertoli cells of neonates,34,35 whereas inhibin was expressed in Leydig cells of both neonate and adult testes.35,36 These studies indicated a possible shift of inhibin production from Sertoli to Leydig cell origin from neonatal to adult life in dogs. Reports on inhibin expression in canine SCTs have been inconsistent. Inhibin α was expressed in 13 of 21 canine SCT34 and none of the 5 canine SCTs.36 Serum inhibin B in this case markedly declined from 805 ng/ml prior to surgery to nondetectable concentrations (< 6 pg/ml) at 3 weeks after tumor removal. Concentrations of serum inhibin B have not been reported in dogs. Inhibin detected by radioimmunoassay (RIA) has been reported for normal intact and castrated dogs as 0.51–2.50, and 0.05– 0.11 ng/ml, respectively.37 Antibody utilized in this assay is known to detect many forms of inhibin, including the free α subunit and inhibin α-β dimers (inhibin A and B).38 Therefore, it is not possible to make a direct comparison between inhibin B concentrations determined by ELISA in the present report inhibin concentrations were determined via RIA. Given the rapid decline in inhibin B to noneditable concen- trations after tumor removal, it would seem reasonable to suspect that the neoplastic testis to be the origin of this hormone in the patient prior to surgery. In the absence of reference ranges for normal intact males, it cannot be deter- mined if concentrations of inhibin B in patient’s presurgi- cal serum sample were due to the presence of normal or neoplastic testicular tissue. The hypothesis that a SCT may be a source of peripheral elevations in serum inhibin con- centrations is supported.3,5 An increase in serum inhib- in-like immunoreactivity was (determined by RIA) detected in 95 and 53 dogs with SCT compared to controls. Further studies to investigate the potential of inhibin B as a marker of gonadal status or neoplastic conditions of the testis may be warranted. Estrone sulphate Estrogen is produced in the male gonad by the aromatiza- tion of androgens through the action of cytochrome P450 aromatase.39 In mammalian species testes, aromatase expres- sion has been predominantly localized to Leydig cells. However, species variations in the cellular distribution of this expression across Leydig, Sertoli, germ cells, and sperm exist.39 Cellular expression of aromatase has also been docu- mented in canine SCTs.40 Estrogens in circulation are com- prised of 3 forms: estradiol, estrone, and estriol. Conjugation of estrone by estrone sulfotransferase resulted in the forma- tion of estrone sulphate.41 Estrone sulphate is produced in substantial quantities in stallion42 and boar43 testis and by the feto-placental unit of many domestic species including mare,44 ewe,45 doe,46 and sow.47 Estradiol concentrations have been variably elevated in cases of SCT3–6 and did not always correlate with feminization.3 Dogs with SCT had significantly higher estradiol concentra- tions compared to controls, although estradiol was only above the reference range for some patients.4,5 It has been suggested that clinical signs of feminization with normal estradiol reflect secretion of other forms of estrogen by SCTs.4 In the present case, serum estrone sulphate concentrations were 1.5 and 1.3 ng/ml in pre and postsurgical samples, respectively. Minimal changes in serum estrone sulphate concentrations after tumor removal in this patient may reflect extra-gonadal sources. However, in the absence of established reference ranges for estrone sulphate in male castrated or intact dogs, the interpre- tation of this result is largely speculative. The clinical signifi- cance of this finding remains undetermined. Histological examination of the neoplastic testis and sper- matic cord revealed tumor emboli within testis and pampin- iform plexus blood vessels, implicating a risk of metastatic disease. Metastatic spread to the medial iliac lymph node has been described.48 However, in the present case, histological evaluation of the enlarged left medial iliac lymph node revealed no neoplastic cells. Preoperative thoracic radio- graphs also had no evidence of pulmonary metastasis. Based on limited literature reports, the rate of metastatic disease in SCT appears to be 2–8%.1,49 However, metastatic spread of SCT has manifested up to 4 years after removal of the pri- mary tumor.50 For cases with metastatic disease, the progno- sis should be considered poor.48,51–54 For these reasons, and in light of significant concentrations of serum AMH concentra- tions remaining 3 weeks after  surgical removal of the neo- plastic testis, an appointment for tumor surveillance 3 months after surgery was recommended. Learning points • AMH is a useful endocrine diagnostic marker for identifi- cation of retained testis in canine patients and may assist in identifying SCT • A precipitous decline in inhibin B to undetectable concen- trations was observed after surgical removal of Sertoli cell-affected retained testis • Effects of hyperestrogenism on hair follicle growth can mimic other more common conditions of alope- cia. Additional diagnostic tests (preputial cytology, ultra- sonography, and hormonal assays) may assist in timely and accurate diagnosis of SCT • The spermatic cord along with the affected testis should be submitted for histologic analysis. Identification of tumor emboli in cord vessels may guide prognosis and follow-up tumor surveillance Conflict of interest Authors have none to declare. http://dx.doi.org/10.58292/CT.v15.9437 6 Citation line: Clinical Theriogenology 2023, 15, 9437, http://dx.doi.org/10.58292/CT.v15.9437 References 1. Lipowitze AJ, Schwartz A, Wilson GP, et al: Testicular neoplasms and concomitant clinical changes in the dog. J Am Vet Med Assoc 1973;163:1364–1368. 2. Reif JS: The relationship between cryptorchidism and canine tes- ticular neoplasia. J Am Vet Med Assoc 1969;155:2005–2010. 3. Grootenhuis AJ, VanSluijs FJ, Klaij IA, et al: Inhibin, gonadotro- phins and sex steroids in dogs with Sertoli cell tumours. J Endocrinol 1990;127:235–242. doi: 10.1677/joe.0.1270235 4. Mischke R, Meurer D, Hoppen HO, et al: Blood plasma concentra- tions of oestradiol-17β, testosterone and testosterone/oestradiol ratio in dogs with neoplastic and degenerative testicular disease. Res Vet Sci 2002;73:267–272. doi: 10.1016/S0034-5288(02)00100-5 5. Peters MAJ, de Jong FH, Teerds KJ, et al: Ageing, testicular tumours and the pituitary-testis axis in dogs. J Endocrinol 2000;166:153– 161. doi: 10.1677/joe.0.1660153 6. Ström Holst B, Dreimanis U: Anti-Mullerian hormone: a potentially useful biomarker for the diagnosis of canine Sertoli cell tumours. BMC Vet Res 2015;11:166–173. doi: 10.1186/s12917-015-0487-5 7. Atalan G, Holt PE, Barr JF: Ultrasonographic estimation of pros- tate size in normal dogs and relationship to bodyweight and age. J Small Anim Pract 1999;40:199–122. doi: 10.1111/j.1748- 5827.1999.tb03052.x 8. Ruel Y, Barthez PY, Mailles A, et al: Ultrasonographic evaluation of the prostate in healthy intact dogs. Vet Radiol Ultrasound 1998;39:112–216. doi: 10.1111/j.1740-8261.1998.tb00342.x 9. Mecklenburg L: Canine hyperestrogenism. In: Mecklenburg L, Linek M, Desomond JT: editors. Hair Loss Disorders in Domestric Animals. 1st Edition, Ames; Wiley-Blackwell: 2009. p.93–175. 10. Hu H, Zhang S, Lei X, et al: Estrogen leads to reversible hair cycle retardation through inducing premature catagen and maintaining telogen. PLoS One 2012;7:e40124. doi: 10.1371/journal. pone.0040124 11. Dreimanis U, Vargmar K, Falk T, et al: Evaluation of preputial cytology in diagnosing oestrogen producing testicular tumours in dogs. J Small Anim Pract 2012;53:536–541. doi: 10.1111/ j.1748-5827.2012.01261.x 12. Josso N, di Clemente N: TGF-b family members and gonadal development. Trends Endocinol Metab 1999;10:216–222. doi: 10.1016/S1043-2760(99)00155-1 13. Josso N: AntiMullerian hormone: new perspectives for a sexist mol- ecule. Endocrinol Rev 1986;7:421–433. doi: 10.1210/edrv-7-4-421 14. Racine C, Rey R, Maguelone G, et al: Receptors for anti-Mullerian hormone on Leydig cells are responsible for its effects on ste- roidogenesis and cell differentiation. Proc Nat Acad Sci 1998;95:594–599. doi: 10.1073/pnas.95.2.594 15. Lasala C, Carre-eusebe D, Picard J, et al: Subcellular and molecu- lar mechanisms regulating anti-Müllerian hormone gene expres- sion in mammalian and nonmammalian species. DNA Cell Bio 2004;23:572–585. doi: 10.1089/dna.2004.23.572 16. Josso E, Rey RA, Picard J: Anti-Müllerian hormone: a valuable addition to the toolbox of the pediatric endocrinologist. Int J Endocrinol 2013;2013:674105. doi: 10.1155/2013/674105 17. Axel PN, Themmen D, Kalra B, et al: The use of anti-Müllerian hormone as diagnostic for gonadectomy status in dogs. Theriogenology 2016;86:1467–1474. doi: 10.1016/j.theriogenol- ogy. 2016.05.004 18. Gharagozlou F, Youssefi R, Akbarinejad V, et al: Anti-Müllerian hormone: a potential biomarker for differential diagnosis of cryptorchidism in dogs. Vet Rec 2014;175:460. doi: 10.1136/ vr.102611 19. Claes A, Ball BA, Almeida J, et al: Serum anti-Müllerian hormone concentrations in stallions: developmental changes, seasonal vari- ation, and differences between intact stallions, cryptorchid stal- lions, and geldings. Theriogenology 2013;79:1229–1235. doi: 10.1016/j.theriogenology.2013.03.019 20. Kitahara G, Ali HE, Sato T, et al: Anti-Mullerian hormone (AMH) profiles as a novel biomarker to evaluate the existence of a func- tional cryptorchid testis in Japanese Black calves. J Reprod Dev 2012;58:310–315. doi: 10.1262/jrd.11-072T 21. Banco B, Veronesi MC, Giudice C, et al: Immunohistochemical evaluation of the expression of anti-Mullerian hormone in mature, immature and neoplastic canine Sertoli cells. J Comp Pathol 2012;143:239–247. doi: 10.1016/j.jcpa.2010.04.001 22. Hitoshi A, Hidaka Y, Katamoto H: Evaluation of anti-Mullerian hormone in a dog with a Sertoli cell tumour. Vet Dermatol 2014;25:142–146. doi: 10.1111/vde.12112 23. Ying SY: Inhibins, activins, and follistatins: Gonadal proteins modulating the secretion of follicle-stimulating hormone. Endocr Rev 1988;9:267–293. doi: 10.1210/edrv-9-2-267 24. Jin W, Arai KY, Herath CB, et al: Inhibins in the male Gottingen miniature pig: Leydig cells are the predominant source of inhibin B. J Androl 2001;22:951–960. doi: 10.1002/j.1939-4640.2001. tb03435.x 25. Ball BA, Davolli GM, Esteller-Vico A, et al: Inhibin-A and inhib- in-B in stallions: seasonal changes and changes after down-regulation of the hypothalamic-pituitary-gonadal axis. Theriogenology 2019;123:108–115. doi: 10.1016/j.theriogenol- ogy. 2018.09.036 26. Woodruff TK, Besecke LM, Groome N, et al: Inhibin A and inhibin B are inversely correlated to follicle-stimulating hormone, yet are discordant during the follicular phase of the rat estrous cycle, and inhibin A is expressed in a sexually dimorphic manner. Endocrinol 1996;137:5463–5467. doi: 10.1210/endo.137.12.8940372 27. Anawalt BD, Bebb RA, Matsumoto AM, et al: Serum Inhibin B levels reflect Sertoli cell function in normal men and men with testicular dysfunction. J Clin Endocrinol Metab 1996;81:3341– 3345. doi: 10.1210/jc.81.9.3341 28. Meachem SJ, Nieschlag E, Simoni M: Inhibin B in male reproduc- tion: pathophysiology and clinical relevance. Eur J Endocrinol 2001;145:561–571. doi: 10.1530/eje.0.1450561 29. Andersson A, Müller J, Skakkebaek NE: Different roles of prepu- bertal and postpubertal germ cells and Sertoli cells in the regula- tion of serum inhibin B levels. J Clin Endocrinol Metab 1998;83:4451–4458. doi: 10.1210/jc.83.12.4451 30. Kaneko H, Noguchi J, Kikuchi K, et al: Molecular weight forms of inhibin A and inhibin B in the bovine testis change with age. Biol Reprod 2003;68:1918–1925. doi: 10.1095/biolreprod.102.012856 31. McNeilly AS, Souza CJH, Baird DT, et al: Production of inhibin A not B in rams: changes in plasma inhibin A during testis growth, and expression of inhibin/activin subunit mRNA and protein in http://dx.doi.org/10.58292/CT.v15.9437 https://doi.org/10.1677/joe.0.1270235 https://doi.org/10.1016/S0034-5288(02)00100-5 https://doi.org/10.1677/joe.0.1660153 https://doi.org/10.1186/s12917-015-0487-5 https://doi.org/10.1111/j.1748-5827.1999.tb03052.x https://doi.org/10.1111/j.1748-5827.1999.tb03052.x https://doi.org/10.1111/j.1740-8261.1998.tb00342.x https://doi.org/10.1371/journal.pone.0040124 https://doi.org/10.1371/journal.pone.0040124 https://doi.org/10.1111/​j.1748-5827.2012.01261.x https://doi.org/10.1111/​j.1748-5827.2012.01261.x https://doi.org/10.1016/S1043-2760(99)00155-1 https://doi.org/10.1210/edrv-7-4-421 https://doi.org/10.1073/pnas.95.2.594 https://doi.org/10.1089/dna.2004.23.572 https://doi.org/10.1155/2013/674105 https://doi.org/10.1016/j.theriogenology.​2016.05.004 https://doi.org/10.1016/j.theriogenology.​2016.05.004 https://doi.org/10.1136/vr.102611 https://doi.org/10.1136/vr.102611 https://doi.org/10.1016/j.theriogenology.2013.03.019 https://doi.org/10.1262/jrd.11-072T https://doi.org/10.1016/j.jcpa.2010.04.001 https://doi.org/10.1111/vde.12112 https://doi.org/10.1210/edrv-9-2-267 https://doi.org/10.1002/j.1939-4640.2001.tb03435.x https://doi.org/10.1002/j.1939-4640.2001.tb03435.x https://doi.org/10.1016/j.theriogenology.​2018.09.036 https://doi.org/10.1016/j.theriogenology.​2018.09.036 https://doi.org/10.1210/endo.137.12.8940372 https://doi.org/10.1210/jc.81.9.3341 https://doi.org/10.1530/eje.0.1450561 https://doi.org/10.1210/jc.83.12.4451 https://doi.org/10.1095/biolreprod.102.012856 Citation line: Clinical Theriogenology 2023, 15, 9437, http://dx.doi.org/10.58292/CT.v15.9437 7 adult testis. Reproduction 2002;123:827–835. doi: 10.1530/ rep.0.1230827 32. Ohnuma K, Kaneko H, Noguchi J, et al: Production of inhibin A and inhibin B in boars: changes in testicular and circulating levels of dimeric inhibins and characterization of inhibin forms during testis growth. Domest Anim Endocrinol 2007;33:410–421. doi: 10.1016/j.domaniend.2006.08.004 33. Tanaka Y, Taniyama H, Tsunoda N, et al: The testis as a major source of circulating inhibins in the male equine fetus during the second half of gestation. J Androl 2002;23:229–236. 34. Banco B, Giudice C, Veronesi MC, et al: An immunohistochemical study of normal and neoplastic canine Sertoli cells. J Comp Pathol 2010;143:239–247. doi: 10.1016/j.jcpa.2010.04.001 35. Grieco V, Banco B, Ferrari A, et al: Inhibin-α immunohistochemi- cal expression in mature and immature canine Sertoli and Leydig cells. Reprod Domest Anim 2011;46:920–923. doi: 10.1111/j.1439-0531.2011.01784.x 36. Taniyama H, Hirayama K, Nakada K, et al: Immunohistochemical detection of inhibin-alpha, -betaB, and -betaA chains and 3beta-hydroxysteroid dehydrogenase in canine testicular tumors and normal testes. Vet Pathol 2001;38:661–666. doi: 10.1354/ vp.38-6-661 37. Bromel C, Nelson RW, Feldman EC, et al: Serum inhibin concen- tration in dogs with adrenal gland disease and in healthy dogs. J Vet Intern Med 2013;27:76–82. doi: 10.1111/jvim.12027 38. Robertson DM, Giacometti M, Foulds LM: Isolation of inhibin α-subunit precursor proteins from bovine follicular fluid. Endocrinol 1989;125:2141–2149. doi: 10.1210/endo-125-4-2141 39. Carreau S, Genissel C, Bilinska B, et al: Sources of oestrogen in the testis and reproductive tract. Int J Androl 1999;22:211–223. doi: 10.1046/j.1365-2605.1999.00172.x 40. Peters MAJ, Mol JA, van Wolferen ME, et al: Expression of the insu- lin-like growth factor (IGF) system and steroidogenic enzymes in canine testis tumors. Reprod Biol Endocrinol 2003;1:22. doi: 10.1186/1477-7827-1-22 41. Barbosa AS, Feng Y, Yu C, et al: Estrogen sulfotransferase in the metabolism of estrogenic drugs and in the pathogenesis of dis- eases. Expert Opin Drug Metab Toxicol 2019;5:329–399. doi: 10.1080/17425255.2019.1588884 42. Raeside JI: Seasonal changes in the concentration of estrogen and testosterone in the plasma of the stallion. Anim Reprod Sci 1979;1:205–212. doi: 10.1016/0378-4320(79)90002-2 43. Hoffmann B, Rostalski A, Mutembei HM, et al: Testicular steroid hormone secretion in the boar and expression of testicular and epididymal steroid sulphatase and estrogen sulphotransferase. Exp Clin Endocrinol Diabetes 2010;118:274–280. doi: 10.1055/s-0029-1231082 44. Conley AJ: Review of the reproductive endocrinology of the preg- nant and parturient mare. Theriogenology 2016;86:355–365. doi: 10.1016/j.theriogenology.2016.04.049 45. Tsang CPW: Plasma levels of estrone sulfate, free estrogens and pro- gesterone in the pregnant ewe throughout gestation. Theriogenology 1978;10:97–110. doi: 10.1016/0093-691X(78)90084-5 46. Refsal KR, Marteniuk JV, Williams CSF, et al: Concentrations of estrone sulfate in peripheral serum of pregnant goats: relation- ships with gestation length, fetal number and the occurrence of fetal death. Theriogenology 1991;36:449–461. doi: 10.1016/ 0093-691X(91)90474-R 47. Hattersley JP, Drane HM, Matthews JG, et al: Estimation of oes- trone sulphate in the serum of pregnant sows. J Reprod Fertil 1980;58:7–12. doi: 10.1530/jrf.0.0580007 48. Withers SS, Lawson CM, Burton AG, et al: Management of an invasive and metastatic Sertoli cell tumor with associated myelo- toxicosis in a dog. Can Vet J 2016;57:299–304. 49. Weaver AD: Survey with follow-up of 67 dogs with testicular ser- toli cell tumours. Vet Rec 1983;113:105–106. doi: 10.1136/ vr.113.5.105 50. Gopinath D, Draffan D, Philbey AW, et al: Use of intralesional oestradiol concentration to identify a functional pulmonary metastasis of canine sertoli cell tumour. J Small Anim Pract 2009;50:198–200. doi: 10.1111/j.1748-5827.2008.00671.x 51. Barrand KB, Scudamo CL: Canine hypertrophic osteoarthropathy associated with a malignant Sertoli cell tumour. J Small Anim Prac 2001;42:143–145. doi: 10.1111/j.1748-5827.2001.tb02011.x 52. Dhaliwal RS, Kitchell BE, Knight BL, et al: Treatment of aggressive testicular tumors in four dogs. J Am An Hosp Assoc 1999;35:311– 318. doi: 10.5326/15473317-35-4-311 53. Theilen GH, Madewell BR: Tumors of the genital system. In: Madewell BR, Theilen GH: editors. Veterinary cancer medicine. 2nd edition, Philadelphia; Lea and Febiger: 1987. p. 583–600. 54. Warland J, Constantino-Casas F, Dobson J: Hyperoestrogenism and mammary adenosis associated with a metastatic Sertoli cell tumour in a male Pekingese dog. Vet Quart 2014;31:211–214. doi: 10.1080/01652176.2011.653593 http://dx.doi.org/10.58292/CT.v15.9437 https://doi.org/10.1530/rep.0.1230827 https://doi.org/10.1530/rep.0.1230827 https://doi.org/10.1016/j.domaniend.2006.08.004 https://doi.org/10.1016/j.jcpa.2010.04.001 https://doi.org/10.1111/j.1439-0531.2011.01784.x https://doi.org/10.1354/vp.38-6-661 https://doi.org/10.1354/vp.38-6-661 https://doi.org/10.1111/jvim.12027 https://doi.org/10.1210/endo-125-4-2141 https://doi.org/10.1046/j.1365-2605.1999.00172.x https://doi.org/10.1186/1477-7827-1-22 https://doi.org/10.1080/17425255.2019.1588884 https://doi.org/10.1016/0378-4320(79)90002-2 https://doi.org/10.1055/s-0029-1231082 https://doi.org/10.1016/j.theriogenology.2016.04.049 https://doi.org/10.1016/0093-691X(78)90084-5 https://doi.org/10.1016/​0093-691X(91)90474-R https://doi.org/10.1016/​0093-691X(91)90474-R https://doi.org/10.1530/jrf.0.0580007 https://doi.org/10.1136/vr.113.5.105 https://doi.org/10.1136/vr.113.5.105 https://doi.org/10.1111/j.1748-5827.2008.00671.x https://doi.org/10.1111/j.1748-5827.2001.tb02011.x https://doi.org/10.5326/15473317-35-4-311 https://doi.org/10.1080/01652176.2011.653593