[Intersexuality in dogs: causes and genetics].

Failures in the establishment of chromosomal, gonadal and phenotypic sex can cause intersexuality in dogs. Thus, diagnosis of chimaerism, mosaicism, sex reversal syndrome, and male or female pseudohermaphroditism in intersex individuals has to be based on the inspection of the chromosomes, gonads and the phenotypic appearance of the reproductive organs. In a study over two years, seven dogs of different breeds suspected to be intersexes were cytogenetically investigated. A sry-negative XX-sex reversal syndrome was diagnosed in a Jack Russel Terrier. In a mixbred dog a persistent Mullerian duct syndrome (PMDS) was found and a Border Terrier Dog showed an XX/XY chromosomal chimaerism. In further four dogs of different breeds, a female constitution of sex chromosomes was seen. As a sign of intersexuality each of these dog showed an enlarged clitoris. A differentiation between XX-sex reversal syndrome and female pseudohermaphroditism was not possible because there was no information on the internal genital tract and gonads available.