Inherited Diseases of the Reproductive Tract in Dogs and Cats

Introduction

Many veterinarians encounter an abnormality of sexual development during the course of routine practice, particularly during surgery for neutering dogs and cats. Theriogenologists are also likely to encounter these through their evaluations of infertile dogs and cats, and we are motivated to reach a definitive diagnosis. In addition to helping the owner and breeder, this careful "phenotyping" is also needed to further research, with the goal of determining the genetic basis of these disorders. Such research has led to the development of practical genetic tests for other inherited disorders and is proving successful in reducing production of affected cats and dogs. To simplify the diagnostic plan, we can categorize affected animals according to the first step in sexual development that is identified as abnormal. These were identified as either errors in chromosomal sex, gonadal sex, or phenotypic sex. In that scheme phenotypic sex includes the internal and external genitalia, but excludes the gonad. This is still a practical plan, but requires incorporation of the new nomenclature for disorders of sexual development that was first developed for human patients is now used for animals. In addition to incorporating molecular diagnosis, the new nomenclature replaces older terms that are outdated and/or confusing. For example, the general term intersex has been replaced with disorder of sexual development (DSD), and the terms hermaphrodite and pseudohermaphrodite have been eliminated. Disorders of sexual development are now divided into three main categories: sex chromosome DSD, XX DSD, and XY DSD. The examples below illustrate how the diagnostic plan and the new nomenclature can be integrated to reach a definitive diagnosis. Previous terminology is included for reference purposes. Other canine and feline examples are also reviewed. [...]