Disorders of sexual development in dogs and cats.

Determination of a mammal’s sex begins at conception with the establishment of genotype and continues from there as the expression of specific genes directs the bipotential gonad to develop. The gonad further directs the sexual differentiation of the individual. Deviations from either of these pathways at any stage results in disorders of sexual development. Definitive diagnosis minimally requires a karyotype, histopathologic evaluation of the gonads, and gross description of the genital anatomy, with more complete diagnostic answers achieved through other diagnostic tests. This article covers normal and abnormal development of the reproductive organs with emphasis on diagnosis and treatment.