Cryptorchid Colt, Missing Equipment?

Q: My mare foaled recently and the colt's testicles and umbilicus are set way back between the hind legs, more than normal. The veterinarian checked him and said he can't feel the penis. He has not seen anything like this before. Any ideas where I could find information about this condition?

via e-mail

A: Thanks for the question. Without having examined this foal firsthand, I can provide a couple of reasons for what you describe.

First, a situation in which the testicles are "way back" might be the failure of the testicles to move into the scrotum. In the normal fetal colt the testicles descend from the abdomen into the scrotum typically by the last month of pregnancy. If one or both testicles are not in the scrotum at birth, the resulting condition is called "cryptorchidism," and the foal might be referred to as a "crypt." In the instance that the testicle(s) is(are) high in the inguinal skin or the inguinal canal (the canal connecting the abdomen to the scrotum) the colt is described as an "inguinal crypt," or a "high flanker." This is different than an abdominal cryptorchid case, in which the testicles are higher in the abdomen.

Compared to other species, the umbilical cord remnant in the horse might sometimes appear to be set further back along the abdomen when, in fact, it is normal. However, developmental abnormalities of the umbilical cord and umbilical region can occur. Conditions to check for include umbilical hernias, infections of the umbilical cord, and patent urachus (the opening in the fetal structure connecting the urinary bladder to the umbilical cord).

Most neonatal colts will extend their penises from the sheath (prepuce) during the first day after birth. However, some colts may not extend the penis for a couple of days or longer. The neonatal penis can sometimes be difficult to palpate within the sheath. But again, there are developmental abnormalities that should be considered when evaluating any possible abnormal location of the penis.

Certain intersex conditions (commonly referred to as pseudohermaphrodites and hermaphrodites) are characterized by an abnormally located and abnormally appearing penile structure. An intersex foal can easily be mistaken as a filly due to the appearance and location of the penile structure when, in fact, the foal may be a genetic male (having the XY sex chromosome combination; for more information see "XY Sex Reversal in Horses") with abdominal (cryptorchid) testicles. An intersex condition would be high on the list of reasons for the combination of an abnormally located penis and cryptorchidism. Another possible developmental condition is hypospadias, in which the location of the urethra in relation to the penis is abnormal.

About the Author

Marc Knobbe, DVM, MPH, Dipl. ACT

Marc Knobbe, DVM, MPH, Dipl. ACT, is a veterinarian based in Philadelphia, Pa.

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