Dog with mixed sex chromosomes and underdeveloped reproductive organs

Abstract

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-M&#xfc;llerian 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.