Disorders of sexual development in the dog and cat.

Normal sexual differentiation occurs in three sequential steps--establishment of chromosomal (genetic) sex, development of gonadal sex, and development of phenotypic sex. Errors in the establishment of chromosomal, gonadal, or phenotypic sex cause abnormal sexual differentiation. Affected individuals are identified with a wide variety of patterns from ambiguous genitalia, to apparently normal genitalia with sterility or infertility. When a patient is suspected of having a disorder of sexual development, analysis of the chromosomal constitution and complete gross and histopathologic description of the gonads, internal and external genitalia are required to correctly categorize the type of disorder.