Canine cryptorchidism: An update

Computed Tomography Assessment of Retained Testes in Dogs

Cryptorchidism consists in the failure of one or both testicles to fully descend into the scrotum. The position of the retained testes can be abdominal or inguinal and may occur unilaterally or bilaterally. This retrospective, multi-center study aimed to describe the computed tomography (CT) features of retained testes in dogs. Nineteen CT scans of dogs, with either unilateral or bilateral cryptorchidism, were analyzed with both pre- and post-contrast imaging. The location, size, shape, margins, homogeneous parenchyma, and density calculated were examined with the Hounsfield unit. Statistical analyses were performed to assess the differences between the scrotal (ST) and undescended testes (UT) and to detect any correlation between the features, ages, and size of the dog. CT identified the retained testes and provided enhanced three-dimensional visualization compared to traditional ultrasound. This study revealed that the UT were significantly smaller than ST, with UT measuring around 70% of ST size. Additionally, the UT exhibited increased density in both pre- and post-contrast scans, potentially due to the reduced or absent spermatogenesis or to histological changes occurring in the parenchyma. While CT showed clear advantages, such as three-dimensional spatial resolution and deeper tissue penetration, limitations such as general anesthesia and radiation exposure should also be considered. However, the present study showed that CT could serve as a valuable second step tool in cases where ultrasound fails, particularly in challenging anatomical situations.

Cryptorchidism in dogs and cats presented for elective gonadectomy: A descriptive cohort study of 306 animals treated between 2018 and 2023

The objective of this study was to describe the incidence, breed distribution, clinical findings (anatomic location, number of testicles affected, and side), and surgical management of cryptorchidism in dogs and cats presented for elective gonadectomy. Medical record abstracts from a non-profit, high-volume, high-quality, spay-neuter clinic from 2018 to 2023 were reviewed retrospectively for cases of elective surgical gonadectomy of cryptorchid dogs and cats. During the study period, 5,476 dogs and 11,559 cats were presented to the same facility for elective surgical castration, suggesting a cryptorchid incidence of 3.21 % for dogs and 1.12 % for cats. Cryptorchidism affects various breeds and body conformations. Cryptorchid testes were more commonly observed in the inguinal area than in the abdomen, and were more frequently located unilaterally on the right side in both dogs and cats. The mean number of overall incisions required for surgical management was higher for testes located in the abdomen than for those located in the inguinal region in both dogs and cats. Due to differences in anatomy, cryptorchid prevalence, and surgical techniques, cryptorchidism in dogs and cats should be evaluated separately. Careful, preemptive identification and localization of the retained testicle(s) can be beneficial for efficient excision of cryptorchid testes.

Is anti-müllerian hormone useful for monorchidism diagnosis in the tomcat?

Monorchidism is an uncommon condition in tomcats, defined by the congenital absence of one of the testicles. Due to the lack of information regarding possible biomarkers, most monorchidism cases require laparotomy in order to differentiate it from cryptorchidism. Human data suggest that monorchid patients have lower serum anti-Müllerian hormone (AMH) levels when compared to cryptorchids, premises that has been also scrutinized in veterinary medicine. Here, we describe a case of monorchidism in a tomcat, focusing on the clinical findings and the dynamics of AMH serum levels before and after the removal of the singularly identified testicle. To contribute to the limited knowledge of AMH levels across different reproductive statuses in tomcats, the findings from this monorchid case were compared to values obtained from two cryptorchid tomcats (one unilateral and one bilateral), three intact tomcats, and three castrated tomcats. In addition, clinical, histopathological and ultrasound examinations were conducted in all tomcats. The AMH levels in the monorchid tomcat revealed a consistent decrease after surgery, from 27.3 ± 0.2 ng/ml when the testicle was still present, to 2.3 ± 0.2 ng/ml 1 week later, and further decreasing below the detection limit (<0.15 ng/ml) for the last 2 weeks of the trial, matching the AMH level of the castrated male. AMH serum levels of the bilateral and unilateral cryptorchid tomcat (22.5 ± 0.3 ng/ml; 24.1 ± 0.2 ng/ml) were in agreement with those of the three intact males (19.1 ± 2.2 ng/ml) and the monorchid prior to surgery. AMH testing effectively confirmed the absence of testicular tissue after unilateral orchiectomy in a monorchid tomcat but did not differentiate between monorchidism and cryptorchidism. To our knowledge, this is the first case of monorchidism in tomcats, in which AMH levels before and after surgery have been determined.

LncRNA-MSTRG.19083.1 Targets NTRK2 as a miR-429-y Sponge to Regulate Circadian Rhythm via the cAMP Pathway in Yak Testis and Cryptorchidism

Long noncoding RNAs (LncRNAs) play essential roles in numerous biological processes in mammals, such as reproductive physiology and endocrinology. Cryptorchidism is a common male reproductive disease. Circadian rhythms are actively expressed in the reproductive system. In this study, a total of 191 LncRNAs were obtained from yak testes and cryptorchids. Then, we identified NTRK2's relationship to circadian rhythm and behavioral processes. Meanwhile, the ceRNA (LncRNA-MSTRG.19083.1/miR-429-y/NTRK2) network was constructed, and its influence on circadian rhythm was revealed. The results showed that NTRK2 and LncRNA-MSTRG.19083.1 were significantly upregulated, and miR-429-y was obviously decreased in cryptorchid tissue; NTRK2 protein was mainly distributed in the Leydig cells of the testis. In addition, the upregulation of the expression level of miR-429-y resulted in the significant downregulation of LncRNA and NTRK2 levels, while the mRNA and protein levels of CREB, CLOCK, and BMAL1 were significantly upregulated; the knockdown of miR-429-y resulted in the opposite changes. Our findings suggested that LncRNA-MSTRG.19083.1 competitively binds to miR-429-y to target NTRK2 to regulate circadian rhythm through the cAMP pathway. Taken together, the results of our study provide a comprehensive understanding of how the LncRNA-miRNA-mRNA networks operate when yak cryptorchidism occurs. Knowledge of circadian-rhythm-associated mRNAs and LncRNAs could be useful for better understanding the relationship between circadian rhythm and reproduction.

Exploring Testicular Descent: Recent Findings and Future Prospects in Canine Cryptorchidism

BACKGROUND

Canine cryptorchidism, manifested by an abnormal testicular position, poses significant health risks and reproductive challenges in affected males. Despite a high prevalence, estimated at up to 10% in the canine population, a comprehensive understanding of its pathogenesis remains elusive. Studies in human cryptorchids and knockout mice have identified key factors involved in testicular descent, including INSL3, RXFP2, and AR. To date, only three DNA variants, found in the RXFP2, HMGA2, and KAT6A genes, have been associated with canine cryptorchidism.

SUMMARY

This review briefly summarizes current knowledge on testicular descent and the factors that regulate this process, based on cryptorchidism in humans and mice. It also highlights recent findings related to canine cryptorchidism, focusing on the INSL3, HMGA2, and KAT6A genes. The most significant results are discussed, with an emphasis on the role of the epididymis in testicular descent. This report presents insights that may facilitate further research aiming to broaden our understanding of canine cryptorchidism pathogenesis.

KEY MESSAGES

DNA polymorphism in the KAT6A gene, associated with changes in global H3K9 acetylation, as well as the DNA methylation pattern in the INSL3 gene, suggest that further research should strongly focus on epigenetic modifications. In addition, the development of the epididymo-testicular junction and the link between cryptorchidism prevalence and dog size should be further investigated.

Effects of Cryptorchidism on the Semen Quality of Giant Pandas from the Perspective of Seminal Plasma Proteomics

Giant pandas are an endangered species with low reproductive rates. Cryptorchidism, which can negatively affect reproduction, is also often found in pandas. Seminal plasma plays a crucial role in sperm-environment interactions, and its properties are closely linked to conception potential in both natural and assisted reproduction. The research sought to identify seminal fluid protein content variations between normal and cryptorchid giant pandas. Methods: Using a label-free MS-based method, the semen proteomes of one panda with cryptorchidism and three normal pandas were studied, and the identified proteins were compared and functionally analyzed. Results: Mass spectrometry identified 2059 seminal plasma proteins, with 361 differentially expressed proteins (DEPs). Gene ontology (GO) analysis revealed that these DEPs are mainly involved in the phosphate-containing compound metabolic, hydrolase activity, and kinase activity areas (p ≤ 0.05). The KEGG functional enrichment analysis revealed that the top 20 pathways were notably concentrated in the adipocyte lipolysis and insulin metabolism pathway, with a significance level of p ≤ 0.05. Further analysis through a protein-protein interaction (PPI) network identified nine key proteins that may play crucial roles, including D2GXH8 (hexokinase Fragment), D2HSQ6 (protein tyrosine phosphatase), and G1LHZ6 (Calmodulin 2). Conclusions: We suspect that the high abundance of D2HSQ6 in cryptorchid individuals is associated with metabolic pathways, especially the insulin signal pathway, as a typical proteomic feature related to its pathological features. These findings offer insight into the ex situ breeding conditions of this threatened species.

Cryptorchidism and testicular cancer in the dog: unresolved questions and challenges in translating insights from human studies†

Cryptorchidism, the failure of one or both testes to descend into the scrotum, and testicular cancer show a strong correlation in both dogs and humans. Yet, long-standing medical debates persist about whether the location of undescended testes directly causes testicular cancer in humans or if both conditions stem from a common origin. Although testicular cancer is a prevalent disease in dogs, even less is known about its cause and correlation with testicular descent in this species. This review investigates the relation between these two disorders in dogs, drawing insights from human studies, and examines key biomarkers identified thus far. In addition, it explores potential causal links, including the impact of temperature on maturing testicular cells and a potential shared genetic origin. Notably, this literature review reveals significant differences between men and dogs in reproductive development, histological and molecular features of testicular tumors, and the prevalence of specific tumor types, such as Sertoli cell tumors in cryptorchid dogs and germ cell tumors in humans. These disparities caution against using dogs as models for human testicular cancer research and underscore the limitations when drawing comparisons between species. The paper concludes by suggesting specific research initiatives to enhance our understanding of the complex interplay between cryptorchidism and testicular cancer in dogs.

Exploring the impact of epidemiological and clinical factors on the progression of canine leishmaniosis by statistical and whole genome analyses: from breed predisposition to comorbidities

Canine leishmaniosis (CanL), caused by Leishmania infantum, is a complex disease of growing importance in Europe. Clinical manifestations result from the down-modulation of the host immune response through multiple host-parasite interactions. Although several factors might influence CanL progression, this is the first known study evaluating risk factors for its different clinical stages in a large referral hospital population (n = 35.669) from an endemic area, over a 20 year period. Genome-wide scans for selection signatures were also conducted to explore the genomic component of clinical susceptibility to L. infantum infection. The prevalence of CanL was 3.2% (16.7% stage I; 43.6% stage II; 32.1% stage III; 7.6% stage IV). Dog breed (crossbreed), bodyweight (<10 kg), living conditions (indoors), regular deworming treatment, and being vaccinated against Leishmania significantly decreased the transmission risk and the risk for developing severe clinical forms. Conversely, the detection of comorbidities was associated with advanced clinical forms, particularly chronic kidney disease, neoplasia, cryptorchidism, infectious tracheobronchitis and urate urolithiasis, although those did not impact the clinical outcome. Significant associations between an increased risk of severe clinical stages and findings in the anamnesis (renal or skin-related manifestations) and physical examination (ocular findings) were also detected, highlighting their diagnostic value in referred cases of CanL. Sixteen breeds were found to be significantly more susceptible to developing severe stages of leishmaniosis (e.g. Great Dane, Rottweiler, English Springer Spaniel, Boxer, American Staffordshire Terrier, Golden Retriever), while 20 breeds displayed a clinical resistantance phenotype and, thus, are more likely to mount an efficient immune response against L. infantum (e.g. Pointer, Samoyed, Spanish Mastiff, Spanish Greyhound, English Setter, Siberian Husky). Genomic analyses of these breeds retrieved 12 regions under selection, 63 candidate genes and pinpointed multiple biological pathways such as the IRE1 branch of the unfolded protein response, which could play a critical role in clinical susceptibility to L. infantum infection.

Single-port laparoscopic-assisted abdominal cryptorchidectomy in 14 dogs

OBJECTIVE

To describe a modified laparoscopic-assisted cryptorchidectomy technique in dogs using a single-port endoscope and evaluate clinical outcome in abdominal cryptorchid dogs that underwent the procedure.

STUDY DESIGN

Prospective case series.

ANIMALS

A total of 14 client-owned dogs (19 abdominal cryptorchid testes).

METHODS

Dogs scheduled for laparoscopic cryptorchidectomy between January 2019 and April 2022 were enrolled in the study. The dogs underwent single-port laparoscopic-assisted cryptorchidectomy (SP-LAC) performed by a single surgeon using a 10-mm single-port endoscope placed in the midline immediately cranial to the prepuce. The abdominal testis was endoscopically located and grasped, the cannula was retracted, the capnoperitoneum was reversed to allow exteriorization of the testis, and the spermatic cord was ligated extracorporeally.

RESULTS

Median age was 13 months (range, 7-29 months) and median bodyweight was 23.0 kg (range, 2.2-55.0 kg). Nine of 14 dogs had unilateral abdominal cryptorchidism (7 right-sided and 2 left-sided) and 5/14 dogs had bilateral abdominal cryptorchidism. Median surgical time for unilateral abdominal cryptorchidectomy was 17 min (range, 14-21 min) and for bilateral abdominal cryptorchidectomy 27 min (range, 23-55 min). Ten dogs had additional surgical procedures performed concurrently with SP-LAC. One major intraoperative complication (testicular artery hemorrhage) occurred that required emergency conversion and two minor entry-related complications were observed.

CONCLUSION

The SP-LAC procedure enabled removal of abdominal testes and was associated with a low morbidity.

CLINICAL SIGNIFICANCE

The SP-LAC procedure can be performed by a single surgeon and represents a less invasive alternative to multi-port laparoscopic-assisted or single-port multi-access laparoscopic cryptorchidectomy techniques.

A massive alteration of gene expression in undescended testicles of dogs and the association of KAT6A variants with cryptorchidism

Cryptorchidism is the most common form of disorder of sex development in male dogs, but its hereditary predisposition is poorly elucidated. The gonadal transcriptome of nine unilaterally cryptorchid dogs and seven control dogs was analyzed using RNA-seq. Comparison between the scrotal and inguinal gonads of unilateral cryptorchid dogs revealed 8,028 differentially expressed genes (DEGs) (3,377 up-regulated and 4,651 down-regulated). A similar number of DEGs (7,619) was found by comparing the undescended testicles with the descended testicles of the control dogs. The methylation status of the selected DEGs was also analyzed, with three out of nine studied DEGs showing altered patterns. Bioinformatic analysis of the cDNA sequences revealed 20,366 SNP variants, six of which showed significant differences in allelic counts between cryptorchid and control dogs. Validation studies in larger cohorts of cryptorchid (n = 122) and control (n = 173) dogs showed that the TT genotype (rs850666472, p.Ala1230Val) and the AA genotype in 3'UTR (16:23716202G>A) in KATA6, responsible for acetylation of lysine 9 in histone H3, are associated with cryptorchidism (P = 0.0383). Both the transcript level of KAT6A and H3K9 acetylation were lower in undescended testes, and additionally, the acetylation depended on the genotypes in exon 17 and the 3'UTR. Our study showed that the massive alteration of the transcriptome in undescended testicles is not caused by germinal DNA variants in DEG regulatory sequences but is partly associated with an aberrant DNA methylation and H3K9 acetylation patterns. Moreover, variants of KAT6A can be considered markers associated with the risk of this disorder.

G Protein-Coupled Estrogen Receptor (GPER) and ERs Are Modulated in the Testis-Epididymal Complex in the Normal and Cryptorchid Dog

There is growing evidence by the literature that the unbalance between androgens and estrogens is a relevant condition associated with a common canine reproductive disorder known as cryptorchidism. The role of estrogens in regulating testicular cell function and reproductive events is supposedly due to the wide expression of two nuclear estrogen receptors (ERs), ER-alpha and ER-beta and a trans-membrane G protein-coupled estrogen receptor (GPER) in the testis. In this study, immunohistochemistry, Western blotting and qRT-PCR were used to assess the distribution and expression of GPER in the testis-epididymal complex in the normal and cryptorchid dog. ER-alpha and ER-beta were also evaluated to better characterize the relative abundances of all three receptors. In addition, in these tissues, the expression level of two proteins as SOD1 and Nrf2 normally associated with oxidative stress was investigated to evaluate a possible relationship with ERs. Our data revealed changes in the distribution and expression of the GPER between the normal and cryptorchid dog. In particular, dogs affected by cryptorchidism showed an upregulation of GPER at level of the examined reproductive tract. Also considering the obtained result of a modulation of SOD1 and Nrf2 expression, we could hypothesize the involvement of GPER in the cryptorchid condition. Further studies are, however, necessary to characterize the role of GPER and its specific signaling mechanisms.

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

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

MicroRNA as epigenetic regulators of canine cryptorchidism

Cryptorchidism, the failed descent of one or both testes into the scrotum, is a common developmental disorder in male dogs. Cryptorchidism may affect canine fertility, reducing the quality of the semen, and may promote spermatic cord torsion and onset of neoplasia. MicroRNAs (miRNAs) are epigenetic regulators of gene expression and their dysregulation is associated with disorders of spermatogenesis and testis neoplasia. The present study aimed at investigating the expression of miRNAs in formalin-fixed, paraffin-embedded (FFPE) canine retained testes and testes affected by seminoma, and at integrating miRNAs to their target genes. Forty testicular FFPE specimens from 30 dogs were included - 10 scrotal and 10 contralateral retained from 10 unilateral cryptorchid dogs; 10 tumoral testes affected by seminoma from non-cryptorchid dogs; 10 scrotal normal testes from non-cryptorchid dogs included as the control. The expression level of three miRNAs, namely miR-302c-3p, miR-302a-3p, and miR-371-3p, associated with testicular disorders, were quantified using RT-qPCR. The comparative analysis demonstrated that the level of miR-302a-3p and miR-371a-3p were quantifiable exclusively in control testes. The expression level of miR-302c-3p was higher in the control than in the other groups; its expression decreased in retained testes compared to scrotal testes and testes with seminoma. Gene Ontology analysis pointed out that these miRNAs may be involved in the modulation of estrogen and thyroid hormone signaling pathways. In conclusion, this study demonstrated that miRNAs are dysregulated in canine cryptorchid and seminoma-affected testes compared to control tissues, confirming the pivotal role of miRNAs in cryptorchidism.

[Diagnostic utility of the anti-Mullerian hormone in companion animals]

The anti-Mullerian hormone is a glycoprotein secreted by Sertoli cells in males and granulosa cells in females. The initial identification of this hormone in canine and feline serum was achieved in 2011. Meanwhile, a variety of studies have demonstrated its clinical significance as a tool in the endocrine diagnosis. This review summarizes the current knowledge about anti-Mullerian hormone in small animal reproduction and describes future opportunities for its diagnostic usage.

Update on canine anorchia: A review

Abnormalities of the external genitals are an important issue in dog breeding because of the unfavourable qualities and characteristics of breeds, resulting in consistent economic losses. Despite their significance, little scientific attention has been given to these problems. Although there are several reviews on cryptorchidism in dogs, none have described anorchia. Testicular agenesis is a rare reproductive disorder with a congenital origin. Moreover, no author has described the diagnostic procedure for making a definitive diagnosis of anorchia in dogs. It is important to have a well-structured diagnostic scheme to help practical veterinarians make a confirmatory diagnosis. This review article aims to provide an update on canine anorchia diagnosis based on the poor research studies published in recent years. We have also contributed to the pathogenesis of this disorder using human medicine studies. Finally, the review includes therapeutic hypotheses that can be expanded in future studies.

Musladin-Lueke Syndrome in a Dog: Case Report

The aim of this study is to report the case of a 4-month-old Beagle dog diagnosed with Musladin-Lueke syndrome. The dog appeared to walk on the digits ("tiptoes") with all limbs during ambulation and rigid extension of the carpus, elbow, tarsus, and knee joints during ambulation. Thickening of the fur and auricular cartilage, reduction in radiocarpal, and tibiotarsal joint amplitude, macrocephaly, and lateralized eyes were noticed on physical examination. Echocardiography showed reduced mobility and altered (tortuous) valve morphology. Bilateral abdominal cryptorchidism was confirmed by ultrasonography. Musladin-Lueke syndrome was the presumptive diagnosis, based on the clinical signs presented. The diagnosis was confirmed after DNA testing performed by serial collection of saliva. This is the first paper that describes unprecedented cardiac and reproductive changes of Musladin-Lueke syndrome in which the dog was followed for 2 years, presenting a good quality of life.

Heat stress and hypoxia inhibit the secretion of androgens and induce epithelial-to-mesenchymal transition associated with activated TGF-β/Smad signalling in canine cryptorchidism

Cryptorchidism, as a common congenital disease of canine testes, is mainly caused by factors leading to endocrine abnormalities in testes and infertility in a heat stress and hypoxia microenvironment. Moreover, heat stress and hypoxia, as critical microenvironmental factors, promote epithelial-mesenchymal transition (EMT), which occurs during adult tissue remodelling responses including carcinogenesis and fibrosis and is the main cause of testicular tumours. In this study, we found by haematoxylin-eosin staining that the canine cryptorchid tissue produced a lot of collagen fibres. Also, the quantitative PCR and Western blot results showed that the mRNA and protein levels of the heat stress makers HSP70 and HO-1 and the hypoxia maker HIF-1α are significant higher compared with normal testes. Moreover, we found the expression levels of TGF-βs and its two receptors TGF-βRI and TGF-βRII increased in case of cryptorchidism. From the study in vitro, we found both heat stress and COCl₂ mimic hypoxia inhibited the secretion of testosterone (T) and androstenedione (A4) and promoted the expression of the EMT maker α-SMA and vimentin in Leydig cells, and also that heat stress and COCl₂ stimulated with the TGF-β signalling promoted the expression of TGF-βs and its two type receptors and also the active phosphorylation of Smad2 and Smad3. The use of LY2109761, a receptor inhibitor of TGF-βs/Smad signalling pathway, was associated with heat stress and COCl₂ suppression of androgens' secretion and stimulated EMT in Leydig cells. These findings characterized a novel pathogenesis of cryptorchidism and provided a new idea for therapeutics.

Whole genome sequencing identifies a missense polymorphism in PADI6 associated with testicular/ovotesticular XX disorder of sex development in dogs

Disorders of sex development (DSDs) are congenital malformations defined as discrepancies between sex chromosomes and phenotypical sex. Testicular or ovotesticular XX DSDs are frequently observed in female dogs, while monogenic XY DSDs are less frequent. Here, we applied whole genome sequencing (WGS) to search for causative mutations in XX DSD females in French Bulldogs (FB) and American Staffordshire Terries (AST) and in XY DSD Yorkshire Terries (YT). The WGS results were validated by Sanger sequencing and ddPCR. It was shown that a missense SNP of the PADI6 gene, is significantly associated with the XX DSD (SRY-negative) phenotype in AST (P = 0.0051) and FB (P = 0.0306). On the contrary, we did not find any associated variant with XY DSD in YTs. Our study suggests that the genetic background of the XX DSD may be more complex and breed-specific.

Serum anti-Müllerian hormone concentration as a diagnostic tool to identify testicular tissue in canine disorders of sexual development

Disorders of sexual development (DSD) may have their origin in alterations of the chromosomal, gonadal or phenotypic sex. Affected animals are usually presented because of ambiguous external genitalia, seldom because of reproductive disorders. Anti-Müllerian hormone (AMH) is secreted in the gonads with higher amounts in males than in females and can be used to identify gonadal tissue in sexually normally developed dogs. The aim of this study was to examine the diagnostic potential of serum AMH to identify testicular tissue in 11 dogs with DSD. The diagnostic procedures applied were: determination of the phenotypic sex (n = 11), genital ultrasound (n = 9), determination of the SRY gene (n = 11), karyogram (n = 6), gonadectomy (n = 11), pathohistology of the gonads (n = 10), serum AMH measurement (n = 11). 39 female dogs described in a previous study and 19 male dogs with a normal spermiogram served as controls for the AMH serum concentrations in sexually intact dogs. The 11 dogs with DSD were classified as 7 XY DSD and 4 XX DSD. Presumptive testes were obtained in 10 dogs and 1 dog had an ovotestis combined with a testis. Mean serum AMH values of the dogs with DSD were significantly higher (P < 0.001) than in male and female controls. The upper limit of the AMH test (≥ 23ng/ml) was reached in 6 dogs. High AMH concentrations have been described previously in cryptorchid dogs. 1 dog with a male phenotype and 2 with a female phenotype had AMH values within the range of the male controls, although all of them had cryptorchid testes. A Poodle, in which epididymis were identified but no definitive gonads, had an AMH concentration of the lower limit of the test (≤ 0.01 ng/ml), comparable to previously described castrated dogs. This study indicates that serum AMH levels are a useful diagnostic tool to identify testicular tissue in dogs with DSD and suggests the possible use of AMH to diagnose testicular dysgenesis.

Case Report: Orchiopexy in Two Poodle Dogs and Its Effect on Their Sperm Quality Parameters

Cryptorchidism is a common congenital abnormality encountered in veterinary clinics. The treatment of choice for this condition is a surgical procedure named orchiectomy or orchidectomy, where the retained testicle is removed. Surgical placement and fixation of the cryptorchid testicle into the scrotum, referred to as orchiopexy, is used in humans. However, due to the hereditary nature of cryptorchidism in dogs, this treatment option has not been proposed in veterinary clinics. Two adult Poodle dogs were referred to our research facility for a sperm parameter evaluation check. The two dogs were unilateral cryptorchid dogs treated with orchiopexy before the age of 6 months. Their sperm kinematics and morphology were within normal ranges, and their libido and testicles sizes were normal. Treatment of unilateral cryptorchidism by orchiopexy in dogs before the age of 6 months successfully restored spermatogenic function and sperm quality-related parameters. However, due to the nature of this condition, orchiectomy remains the treatment of choice.

Copy number variation of the SRY gene showed an association with disorders of sex development in Yorkshire Terrier dogs

The molecular background of disorders of sex development (DSD) in dogs is poorly understood. Several copies of the SRY genes have been reported in the dog genome. We used droplet digital PCR with the aim of determining variability in SRY copy number and its association with DSD in dogs. Altogether 19 DSD male dogs (XY DSD) of 10 breeds and 87 control dogs of eight breeds were analyzed. Moreover, we performed a comparative analysis of SRY copy number in other canids: wolves (3), red foxes (16), and Chinese raccoon dogs (10). We found that the modal number of SRY copies in dogs, wolves, red foxes, and Chinese raccoon dogs was 3, 3, 1, and 3 respectively. Variability of copy number was only observed in Yorkshire Terriers (two or three copies) and red foxes (one or two copies). An analysis of six DSD Yorkshire Terriers and 38 control males of this breed showed that 50% of the DSD dogs had two copies, while the incidence of this variant was significantly lower in the control dogs (10.5%). Searching for the copy number of the coding and 5'-flanking fragments revealed full concordance with the copy number. These fragments were also sequenced in DSD (19) and control (24) dogs, and no DNA variants were found. We conclude that, in the dog, two or three functional copies of the SRY gene are present, and a smaller number of copies showed an association with the risk of DSD phenotype in Yorkshire Terriers.

Immunohistochemical insights into a hidden pathology: Canine cryptorchidism

Cryptorchidism is a common disorder in the canine population with some aspects still unclear. Although the bilateral condition is known to lead to fertility problems and predisposition to testicular cancer, the neoplastic risk for scrotal testis in unilateral cryptorchid dog is controversial. Therefore, the therapeutic approach to the canine unilateral cryptorchid is arbitrary so far. This study aimed to investigate precancerous testicular lesions, such as immaturity and atrophy, and compare them in scrotal and undescended testes using an in-depth diagnostic analysis based on immunophenotypic patterns. With this purpose, 26 adult male dogs of different ages and breeds, affected by unilateral or bilateral cryptorchidism were enrolled. After surgical removal, testes were examined immunohistochemically to assess their positivity for specific markers of the canine foetal/neonatal period, that is vimentin (VIM), cytokeratin (CK), desmin (DES), inhibin-α (INH), and anti-Müllerian hormone (AMH) in Sertoli cells, and placental alkaline phosphatase (PLAP) in germ cells. Except for the ubiquitous VIM, all the markers were more expressed in neoplastic gonads compared to healthy ones (P < 0.05). Similarly, testes detected with Sertoli cell-only tubules as well as with Sertoli cells hyperplasia showed higher expression than gonads without such alterations for CK, DES, AMH and PLAP, and for CK and DES, respectively (P < 0.05). The same trend was observed in undescended respect to scrotal testes even though their positivity was significant only for DES, INH and AMH (P < 0.05). Immunohistochemical positivity found in scrotal testes of unilateral cryptorchid dogs, even in absence of detectable anatomical abnormalities, was suggestive of precancerous lesions. Despite the limited sample size, this study could help to clarify the predisposition to neoplastic development in normally descended testes. These markers expression in adult life could allow identifying the early stages of the testicular carcinogenesis process besides suggesting a precautionary bilateral surgical approach in unilateral cryptorchid dogs.

Case of Anorchia in a Mixed-Breed Dog

Anorchia is a rare and often poorly understood disorder of sexual development. In the present case report, we used a multidisciplinary approach to diagnose a case of anorchia in a 30-month old dog. The diagnostic process began with gathering the dog medical history followed by a clinical visit with the patient, which included a general wellness examination as well as an examination of the genital system. As suggested in the relevant literature, the dog underwent an ultrasound and then computed tomography (CT) of the genital system, which confirmed the diagnosis of testicular agenesis. Genetic testing confirmed the male XY karyotype. Hormone testing also supported the diagnosis: testosterone and anti-Müllerian hormone levels were below their reference ranges, and luteinizing hormone (LH) was above 1 ng/mL. Following the diagnostic procedures suggested in the relevant literature, the present study confirms anorchia in the dog and describes a case of testicular agenesis in the canine species.

Bowel incarceration within the vaginal tunic in a three-and-half-year-old bilaterally cryptorchid Lhasa Apso

BACKGROUND

Cryptorchidism in dogs is of clinical concern due to its association with development of Sertoli cell tumours, seminomas and spermatic cord torsion. A patent inguinal ring has been found as a risk factor for peritoneal content migration and inguinal hernias. This study reports a case of bowel migration through a patent inguinal ring in a bilaterally cryptorchid dog and incarceration within the vaginal tunic of the left testicle.

CASE PRESENTATION

A three-and-a-half-year-old bilaterally cryptorchid Lhasa Apso with a history of anorexia, vomiting, stranguria and inability to defecate was diagnosed with bowel incarceration in the vaginal tunic of a retained left testicle. Surgery performed under epidural anaesthesia with acepromazine/butorphanol premedication revealed a loop of the colon entrapped in the vaginal tunic of the retained left testicle. The incarcerated bowel was thoroughly examined for viability and repositioned into the abdominal cavity. The inguinal ring was repaired and bilateral cryptorchidectomy performed.

CONCLUSION

Cryptorchidectomy in dogs is often considered when there is concern for neoplasm or torsion of retained testes. However, this report suggests that cryptorchidectomy should be considered also to preclude the possibility of bowel obstructive emergencies.

A five-year cohort study on testicular tumors from a population-based canine cancer registry in central Italy (Umbria)

Canine testicular tumors account for about 90 % of tumors affecting the male genitalia. Seminomas (SEM), Sertoli cell tumors (SCT), and interstitial cell tumors (ICT) are the most common histological diagnoses, but their incidence shows high variability among studies. Our aim is to report the results on the analysis of testicular tumors recorded by the population-based Umbria Canine Cancer Registry (CCR) for a 5-year time period and to assess the value of tumor major diameter, measured during trimming, in discriminating neoplastic from non-neoplastic lesions. The study was conducted on 388 testicular tumors (on 1969 total male tumors) diagnosed in 355 dogs from 2014 to 2018. The median incidence was 35 cases/100,000 dogs, with a proportion equal to 19,7 % of all tumors. The incidence on neutered male dogs was 352/100,000. Most tumors were ICTs (50 %), with fewer SEMs and SCTs (29 % and 17 %, respectively). Only 3 % of tumors were mixed germ cell-sex cord-stromal tumors (MGC-SCST). Ten percent of cases had multiple tumors in the same testicle, with SEM-ICT being prevalent (69.2 %). Tumors in cryptorchid testes were 5.9 % of the total, mostly SCT (60.9 %). Mean age at diagnosis was 10.7 ± 2.7, with similar values for different tumor types. Significant incidence ratios (IRR) were found in Golden retriever (IRR 7.18, CI95 % 4.72-10.92) and in English cocker spaniel (IRR 2.30, CI95 % 1.28-4.13) when compared with mixed breed dogs. A value of 0.3 cm (major diameter) of lesions at the moment of trimming was helpful in discriminating a final tumor histological diagnosis from a non-tumor lesion. Since the number of tumors included in this evaluation was limited, further studies to confirm the diagnostic value of this measure are recommended. Our results provided information on the incidence of canine testicular tumors in Umbria region that can be compared with future results and incidence from other geographical areas if provided with reliable data on the total population, can offer solid information on the incidence and proportion of different tumor types in specific territories, contributing also to the supervision of its inhabitants' health. Moreover, pathological data such as the major diameter of tumors can be obtained and contribute to diagnostic routine and standardization.

Screening for structural variants of four candidate genes in dogs with disorders of sex development revealed the first case of a large deletion in NR5A1

Disorders of sex development (DSD) are important causes of infertility and sterility, and are risk factors for gonadal carcinogenesis. Many DSDs are caused by genetic factors, mainly sex chromosome abnormalities or mutations of genes involved in sexual development, as well as structural variants (SVs) - large deletions, duplications, and insertions, if these overlap genes involved in sex development. The aim of this study was to determine if there were SVs in four candidate genes - NR0B1 (DAX1), NR5A1, RSPO1, and SOX3 - using droplet digital PCR (ddPCR). There was study of two cohorts of dogs with DSD, including 55 animals with XX DSD and 15 with XY DSD. In addition, 40 control females and 10 control males were included in the study. Among cases, for which there were evaluations, a large deletion consisting of four exons of the NR5A1 gene was identified in a Yorkshire Terrier with a rudimentary penis, hypospadias, bilateral cryptorchidism, and spermatogenesis inactive testes. This is the first mutation in the NR5A1 gene leading to XY DSD phenotype to be reported in domestic animals. There were no SVs in the genes evaluated in the present study in the cohort of dogs with XX DSD. The results from this study provide evidence that the large structural variants of these genes are rarely associated with the DSD phenotype in dogs.

Analysis of transcript and methylation levels of INSL3 and RXFP2 in undescended and descended dog testes suggested promising biomarkers associated with cryptorchidism

Cryptorchidism is the most common disorder of sex development (DSD) in dogs. This malformation is associated with reduced fertility and with a higher risk of gonadal cancer. Testicular descent is a complex process, and the functions of many environmental and genetic factors are crucial for the proper migration of fetal gonads into the scrotum. Among these, the hormone INSL3 (insulin-like peptide 3) and its receptor RXFP2 (relaxin family peptide receptor 2) play crucial roles in the transabdominal migration of the testes. The genetic background of canine cryptorchidism is poorly elucidated. The aim of this study was to compare the transcript and methylation levels of INSL3 and RXFP2 genes in undescended and descended testes of isolated unilateral cryptorchids, and in gonads of control male dogs with scrotal testes. Next, we searched for polymorphic variants in the 5'-regulatory regions of both genes associated with predispositions to cryptorchidism. The INSL3 transcript level was significantly higher in the undescended testes than in the descended testes of both the affected and control dogs. On the other hand, the mRNA level of RXFP2 was significantly lower in the retained gonads of cryptorchids than in the scrotal testes. The methylation level of a single CpG site located 15 bp upstream of the translation start codon in INSL3 was significantly higher in the testes of the control dogs than in both gonads of cryptorchids. The methylation level of 14 CpG sites in the coding region of INSL3 was significantly higher in undescended testes than in the scrotal testes, which may be associated with the higher mRNA levels of INSL3 observed in these samples. The methylation pattern of two CpG sites in the 5'-flanking region of RXFP2 was similar in both descended and undescended testes. We detected three and seven single nucleotide polymorphisms (SNPs) in the 5'-regulatory regions of INSL3 and RXFP2, respectively. Among these, the frequency of A > C substitution (ss7093349755) located 495 bp upstream of the transcription start site of RXFP2 differed significantly between cryptorchids and control dogs. Our study showed two possible genetic biomarkers associated with canine cryptorchidism: a hypomethylation of a single CpG site in the 5'-flanking region of INSL3, and the ss7093349755 SNP in the 5'-flanking region of RXFP2.

Laparoscopic gonadectomy in dogs with ovotesticular disorder of sexual development

Disorders of sexual development (DSD) in dogs involve most commonly an XX sex reversal syndrome, treated conventionally by gonadohysterectomy. The objective of the present case series is to describe the surgical treatment and long-term follow-up of dogs undergoing laparoscopic gonadectomy without hysterectomy for treatment of ovotesticular DSD. Six female dogs clinically diagnosed with DSD were retrospectively included in the study when laparoscopic gonadectomy was performed and histology confirmed the presence of abnormal gonads. The dogs were evaluated by ultrasound after 6 months, and owners were contacted by phone for the long-term reevaluation. Laparoscopic gonadectomy was performed using 2- or 3-portal midline techniques with 3- and/or 5-mm instruments. Additional procedures were performed in 5 dogs, including os clitoris removal in 4 dogs and vulvoplasty in 1 dog. Histological analysis of the gonads reported 11 ovotestes and 1 testis. No major or minor complications occurred perioperatively. Ultrasonographic reevaluation was performed in 5/6 dogs and the remaining abdominal genital system was considered normal. Median long-term follow-up was 617 days (range, 265-1597) with none of the dogs having any symptom related to DSD. Therefore, laparoscopic gonadectomy is a valid alternative for dogs with ovotesticular DSD and is less invasive than conventional open techniques. Removal of the gonads avoids future development of hormone-related diseases of the remaining genital tract.

Altered expression of CYP17A1 and CYP19A1 in undescended testes of dogs with unilateral cryptorchidism

Cryptorchidism is the most common disorder of sex development in dogs and testosterone plays a crucial role in the inguinal phase of the testes descending into the scrotum. The molecular background of impaired testosterone synthesis in the testes of cryptorchid dogs is poorly elucidated. In this study, we analyzed the expression of four genes involved in testicular steroidogenesis (CYP17A1, CYP19A1, HSD3B2 and HSD17B3) in undescended and contralateral scrotal testes from inguinal unilateral cryptorchid dogs (n = 13) and from the scrotal gonads of normal males (n = 15). We found that transcript level of CYP17A1 was significantly increased in inguinal gonads, while the level of CYP19A1 was decreased. For these two genes, we analyzed the methylation level of single CpG sites in the promoter region localized within putative target sites for testicular transcription factors (NUR77, CREB, CAR and HSF2). A correlation between decreased methylation in the promoter of CYP17A1 and its increased transcript level in undescended gonads was observed, but the change in protein level was not significant. We also resequenced the 5'-flanking region of both genes and two known polymorphic sites, SNP in CYP17A1 and an indel in CYP19A1, were found. However, the distribution of the variants in affected (n = 80) and control (n = 75) dogs was not associated with cryptorchidism. We tentatively conclude that the altered expression of CYP17A1 and CYP19A1 in undescended testes could be caused by their exposure to increased temperature in the body. Furthermore, we showed that the identified polymorphisms cannot be considered markers associated with a predisposition to cryptorchidism.

Polymorphisms of MAMLD1, SRD5A2, and AR Candidate Genes in Seven Dogs (78,XY; SRY-Positive) Affected by Hypospadias or Cryptorchidism

Knowledge of the molecular background of disorders of sex development (DSD) in dogs with normal sets of XY chromosomes (XY DSD) is very scarce. However, extensive studies have been carried out in humans, showing that polymorphisms and mutations of numerous genes, including SRY, MAMLD1, SRD5A2, and AR, are associated with or responsible for XY DSD. In this study, we analyzed the entire coding sequence of these genes in 7 dogs (78,XY) with ambiguous external genitalia (hypospadias, cryptorchidism, bifid scrotum, or rudimentary penis). The most common disorder was hypospadias (6 cases), followed by cryptorchidism (4 cases). The co-occurrence of both abnormalities was observed in 3 dogs. Polymorphisms were found in MAMLD1 (3 SNPs), SRD5A2 (5 SNPs), and AR (2 STRs and 1 SNP), while SRY was monomorphic. However, the distribution of the polymorphic variants in the DSD dogs and 11 control XY dogs did not differ significantly. Our study suggests that an association between the polymorphisms of the studied candidate genes and hypospadias or cryptorchidism is unlikely in dogs. We thus support the recent suggestion that hypospadias is not rare in this species, and moreover, we show that co-occurrence of hypospadias and cryptorchidism can be quite frequent.