{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,4,2]],"date-time":"2026-04-02T01:02:12Z","timestamp":1775091732645,"version":"3.50.1"},"reference-count":24,"publisher":"American Veterinary Medical Association (AVMA)","issue":"6","content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["javma"],"published-print":{"date-parts":[[2011,3,15]]},"abstract":"<jats:title>Abstract<\/jats:title>\n<jats:p><jats:bold>Case Description<\/jats:bold>\u20142 Standardbred racehorses that had been winning races while competing as mares underwent postrace drug testing and had serum testosterone concentrations above the acceptable limit for female racehorses.<\/jats:p>\n<jats:p><jats:bold>Clinical Findings<\/jats:bold>\u2014Initial physical examinations by the referring veterinarian revealed ambiguous external genitalia and suspected intra-abdominally located testes leading to a preliminary diagnosis of male pseudohermaphroditism. Horses were referred for further evaluation of sex. Physical examination of the external genitalia confirmed the findings of the referring veterinarian. Transrectal palpation and ultrasonography revealed gonads with an ultrasonographic appearance of testes. On cytogenetic analysis, both horses were determined to have a 64,XY karyotype and 8 intact Y chromosome markers and 5 <jats:italic>SRY<\/jats:italic> gene markers, which were indicative of a genetic male and confirmed an intersex condition. Additionally, both horses had some male-type behavior and endocrinologic findings consistent with those of sexually intact males.<\/jats:p>\n<jats:p><jats:bold>Treatment and Outcome<\/jats:bold>\u2014Taken together, these findings confirmed that both horses were male pseudohermaphrodites. Both horses returned to racing competition as males.<\/jats:p>\n<jats:p><jats:bold>Clinical Relevance<\/jats:bold>\u2014As of October 1, 2008, the Pennsylvania Horse and Harness Racing Commissions implemented a postrace drug testing policy that included analysis of blood samples for anabolic and androgenic steroids and set maximum allowable concentrations of testosterone for racing geldings and females. Within 8 months of initiation of this drug testing policy, the 2 horses of this report were identified as having an intersex condition. This raises the possibility that intersex conditions may be more common in racing Standardbreds than was previously suspected.<\/jats:p>","DOI":"10.2460\/javma.238.6.751","type":"journal-article","created":{"date-parts":[[2011,3,15]],"date-time":"2011-03-15T07:02:30Z","timestamp":1300172550000},"page":"751-754","source":"Crossref","is-referenced-by-count":10,"title":["Physical, behavioral, endocrinologic, and cytogenetic evaluation of two Standardbred racehorses competing as mares with an intersex condition and high postrace serum testosterone concentrations"],"prefix":"10.2460","volume":"238","author":[{"given":"Marc G.","family":"Knobbe","sequence":"first","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Cindy","family":"Maenhoudt","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Regina M.","family":"Turner","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Sue M.","family":"McDonnell","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1272","reference":[{"key":"ref1"},{"key":"ref2","series-title":"J Endocrinol Invest","first-page":"609","article-title":"Concentration of serum testosterone in XY sex reversed horses","volume":"11","author":"Kent","year":"1988"},{"key":"ref3","series-title":"Hum Genet","first-page":"321","article-title":"XY Sex reversal syndrome in the mare: clinical and behavioral studies, H-Y phenotype","volume":"79","author":"Kent","year":"1988"},{"key":"ref4","series-title":"Equine Vet Educ","first-page":"299","article-title":"Laparoscopic gonadectomy in two half-sister horses with male pseudohermaphroditism of the testicular feminisation type","volume":"15","author":"Bartmann","year":"2003"},{"key":"ref5","series-title":"Dtsch Tierarztl Wochenschr","first-page":"50","article-title":"Intersexuality in horses","volume":"114","author":"Kuiper","year":"2007"},{"key":"ref6","series-title":"Physiol Rev","first-page":"1","article-title":"Sex determination and gonadal development in mammals","volume":"87","author":"Wilhelm","year":"2007"},{"key":"ref7","series-title":"Proc Natl Acad Sci U S A","first-page":"9321","article-title":"A detailed physical map of the horse Y chromosome","volume":"101","author":"Raudsepp","year":"2004"},{"key":"ref8","series-title":"Theriogenology","first-page":"1597","article-title":"A sporadic case of the sex-reversed mare (64,XY; SRY-negative): molecular and cytogenetic studies of the Y chromosome","volume":"59","author":"Bugno","year":"2003"},{"key":"ref9","series-title":"Equine Vet J","first-page":"336","article-title":"Deletion of the Sry region on the Y chromosome detected in a case of equine gonadal hypoplasia (XY female) with abnormal hormonal profiles","volume":"31","author":"Abe","year":"1999"},{"key":"ref10","series-title":"An update of chromosomal abnormalities in mares","first-page":"149","author":"Bowling","year":"1987"},{"key":"ref11","series-title":"Equine Vet J","first-page":"78","article-title":"SRY-negative, XX inter-sex horses: the need for pedigree studies to examine the mode of inheritance of the condition","volume":"32","author":"Buoen","year":"2000"},{"key":"ref12","series-title":"Equine Vet Sci","first-page":"220","article-title":"Three full sister mares with stallion-like behavior and a high blood testosterone concentration","volume":"13","author":"Cammaert","year":"1993"},{"key":"ref13","series-title":"Equine Vet Educ","first-page":"295","article-title":"Laparoscopic-assisted castration of a monorchid male pseudohermaphrodite pony","volume":"21","author":"Smith","year":"2009"},{"key":"ref14","series-title":"Equine Vet J","first-page":"211","article-title":"Diploid-triploid chimaerism (64,XX\/96,XXY) in an intersex foal","volume":"22","author":"Power","year":"1990"},{"key":"ref15","series-title":"Cornell Vet","first-page":"123","article-title":"Two equine true hermaphrodites with 64,XX\/64,XY and 63,XO\/64,XY chimerism","volume":"71","author":"Dunn","year":"1981"},{"key":"ref16","series-title":"Equine Vet J","first-page":"156","article-title":"An equine cryptorchid with testicular and ovarian tissues","volume":"8","author":"McIlwraith","year":"1976"},{"key":"ref17","series-title":"Cytogenet Genome Res","first-page":"123","article-title":"A case of an intersex horse with 63,X\/64,XX\/65,XX,del(Y)(q?) karyotype","volume":"120","author":"Bugno","year":"2008"},{"key":"ref18","series-title":"Hum Reprod Update","first-page":"314","article-title":"Disorders linked to insufficient androgen action in male children","volume":"7","author":"Sultan","year":"2001"},{"key":"ref19","series-title":"Clin Endocrinol (Oxf","first-page":"173","article-title":"46,XY disorders of sex development (DSD)","volume":"70","author":"Mendonca","year":"2009"},{"key":"ref20","series-title":"J Am Vet Med Assoc","first-page":"1689","article-title":"Testicular feminization syndrome in a mare","volume":"200","author":"Crabbe","year":"1992"},{"key":"ref21","series-title":"Can Vet J","first-page":"501","article-title":"Androgen insensitivity syndrome in a Thoroughbred mare (64,XY\u2014Testicular feminization)","volume":"45","author":"Howden","year":"2004"},{"key":"ref22","series-title":"Mol Reprod Dev","first-page":"266","article-title":"Sry-negative XX sex reversal in purebred dogs","volume":"53","author":"Meyers-Wallen","year":"1999"},{"key":"ref23","series-title":"Dev Dyn","first-page":"39","article-title":"Ontogenesis of female-to-male sex-reversal in XX polled goats","volume":"224","author":"Pailhoux","year":"2002"},{"key":"ref24","series-title":"Anim Reprod Sci","first-page":"117","article-title":"Familial occurrence of pig intersexes (38,XX; 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