Bilateral Ovotestes in a 78, XX SRY-Negative Beagle Dog

[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.

Laparoscopic gonadectomy in a dog with 78,XX/78,XY chimerism and underdeveloped reproductive organs

CASE DESCRIPTION

A 1-year-old externally sexually intact female Great Dane was referred for further evaluation of abnormal and underdeveloped internal reproductive organs.

CLINICAL FINDINGS

Physical examination findings included a cranioventrally displaced vulva and a grade 2/6 left apical systolic heart murmur. No uterus or ovaries were identified during abdominal ultrasonography. Computed tomography with retrograde vaginourethrography revealed an underdeveloped uterus and possible left intra-abdominal gonad. Karyotyping revealed mixed sex chromosomes (70% XY and 30% XX). Analysis of a serum sample yielded positive results for anti-Müllerian hormone; other findings included mid range estradiol concentration (48.2 pg/mL [within reference intervals for sexually intact and neutered males and females]), low progesterone concentration (< 0.2 ng/mL [within reference intervals for anestrous females]), and low testosterone concentration (< 20 ng/dL [similar to the expected concentration in neutered males]). Overall, the results of the sex hormone analyses were consistent with findings for either a sexually intact female or a neutered male dog. The dog's cardiac structure and function were echocardiographically normal.

TREATMENT AND OUTCOME

The dog was anesthetized and underwent laparoscopic gonadectomy. The gonads, although abnormal and underdeveloped, were readily identified intraoperatively and successfully removed. On the basis of histologic findings, the removed gonads were confirmed to be rudimentary testicles. The dog recovered from anesthesia and surgery without complications.

CLINICAL RELEVANCE

Laparoscopic surgery was effective for visualization of abnormal and hypoplastic reproductive organs when abdominal ultrasonography and CT were of limited diagnostic usefulness, and laparoscopic surgery allowed straightforward gonadectomy in a 78,XX/78,XY chimeric dog.

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.

Sex Reversal in Non-Human Placental Mammals

Gonads are very peculiar organs given their bipotential competence. Indeed, early differentiating genital ridges evolve into either of 2 very distinct organs: the testis or the ovary. Accumulating evidence now demonstrates that both genetic pathways must repress the other in order for the organs to differentiate properly, meaning that if this repression is disrupted or attenuated, the other pathway may completely or partially be expressed, leading to disorders of sex development. Among these disorders are the cases of XY male-to-female and XX female-to-male sex reversals as well as true hermaphrodites, in which there is a discrepancy between the chromosomal and gonadal sex. Here, we review known cases of XY and XX sex reversals described in mammals, focusing mostly on domestic animals where sex reversal pathologies occur and on wild species in which deviations from the usual XX/XY system have been documented.