Disorder - Sex reversal

Organ Systems Involved
Urogenital

Alternative Names
XX true hermaphrodites; XX males; XY females; Disorders of gonadal sex

Presenting Signs

Chromosomes are the tiny strands of DNA within cells that determine inherited features. There are two sex chromosomes in mammals; these are called X and Y. The combination of these two determines the sex of an animal. XX results in a female while XY result in a male.

Sex reversal is an inherited disease whereby the chromosomes do not match the animal’s genitals. This can occur in three different ways: XX males, XX true hermaphrodites and XY females. XX males have testicles of normal structure but they produce no sperm cells and thus these animals cannot reproduce. They also have an abnormal prepuce (the sheath covering the penis) and a small penis, which is usually curved. Interestingly, internally these animals often have female organs sometimes including a normal uterus. XX males can go unnoticed as their testes can remain undescended in their abdomen (cryptorchidism). This can have serious consequences such as cancer. XX True hermaphrodites have both testicles and ovaries, called ovotestes. Many hermaphrodites appear as females with a degree of masculinisation and have a normal to abnormal vulva, a normal to enlarged clitoris, a uterus and oviducts. The components of male testes, that is the epididymis and vas deferens, are also present. Like XX males, XX true hermaphrodites are also unable to reproduce, except in very rare cases.

XY females usually have normal female external genitals, however internally, they often have minimal mammary tissue (where milk is produced) and a very small uterus. XY females are also unable to reproduce. These animals will likely demonstrate masculine behaviour and attempt to mate with other female animals.

Cats at Risk

Kittens born to cats that have sex reversed kittens

Treatment

Surgical: ovariohysterectomy and castration are usually recommended

PubMed References
Sex reversal

Contributor
Josie Gollan