Sry-negative XX sex reversal in a family of Norwegian Elkhounds

Two related female Norwegian Elkhounds were evaluated at 6 and 8 months of age for enlarged clitori. Both had a 78 XX karyotype. Histology of their in ternal reproductive tracts demonstrated 1 to be an XX true hermaphrodite wi th bilateral ovotestes and the other to be an XX male with bilateral asperm atogenic testes. Polymerase chain reaction-based tests of genomic DNA showe d that both dogs lacked Sry, the testis-determining gene. Pedigree analysis was consistent with an autosomal recessive mode of inheritance, as has bee n reported in the American Cocker Spaniel and the German Shorthaired Pointe r. This is the Ist reported case of familial Sry-negative XX sex reversal i n the Norwegian Elkhound. A summary of 34 previously unreported cases of do gs with masculinized external genitalia and a normal 78 XX karyotype seen f rom 1980 to 1997 is given.