Hypospadias in Animals

Hypospadias is a rare birth defect of the urethra in males, resulting in the urethral opening having an abnormal placement along the urethral groove that runs from the tip along the underside of the shaft to the junction of the penis and scrotum or perineum. There are no connections to the defect being genetic. The condition can be characterized as mild (first degree), moderate (second degree) or severe (third degree) depending on the placement of the urethral opening. In 50-75% of cases, the defect is determined to be first degree, with the opening on the glans penis. The condition is said to be in second degree (20% of cases) when the opening is on the shaft and in third degree when the opening is on the perineum. The more severe the degree the condition is, the more likely it is to be associated with chordee (a downward curvature of the penis usually seen at erection) or cryptorchidism (undescended testes). It is common to not see any symptoms of the defect, but some animals may exhibit urine scald dermatitis or a pooling of urine in the prepuce if the penis is underdeveloped. Urinary incontinence not stemming from neurological problems is frequent in animals that have hypospadias.

Hypospadias is caused by the inhibition of androgen action in the embryo. This can happen in a few ways. Endocrine disruptors, such as phthalates, DDT (Dichloro-Diphenyl-Trichloroethane) and PCB (Polycholorinated biphenyal) are used in the human world as additives to plastic, pesticides and paints. These interact with the steroid receptors while the fetal male is still in the embryo. An example is prenatal testosterone, which stimulates migration of skin fibroblasts which fully enclose the urethral groove in fetal males. Failure of this to happen, due to the testosterone being inhibited, results in the urethral opening occurring in an abnormal place along the length of the penis. The endocrine disruptors can cause testicular dysgenesis syndrome (TDS), which decreases the function of the Leydig cells. By decreasing their function, androgens are insufficient and can result in hypospadias (although, it can also cause cryptorchidism). The more severe TDS is, the more probable hypospadias can occur. Exogenous estrogens such as diethylstilbestrol, ethinyl estradiol, and bisphenol A can have the same effect on the fetal male if the fetus is exposed to them between day 30 and day 44 of pregnancy. The basic premise is that testosterone is not secreted in correct quantities.

Treatment of the condition is based on the severity. In mild (first degree) hypospadias, it is considered primarily a cosmetic defect. There are no effects on the function of the penis beyond difficulty with the urinary stream. In moderate (second degree) hypospadias, surgery is highly suggested and is done within the first year of life. The surgery done is a two-layer closure, which decreases the possibility of a fistula occurring. If the condition is left uncorrected, it can result in messy urination (no control over urinary stream), impaired delivery of semen into the vagina (which may result in fertility problems), and interference with erections. Severe (third degree) hypospadias, if left untreated, can have the same results as the moderate condition. Usually an animal with a severe condition has a karyotype evaluation done to determine any intersex conditions before surgery is performed. The karyotype can also differentiate between hypospadias and true hermaphroditism. This surgery may have to be done multiple times, and can have effects of scarring, curvature, formation of urethral fistulas, diverticula, or strictures. Fistulas are unwanted openings through the skin along the course of the urethra, usually resulting in abnormal stream or urinary leakage. Diverticula is an "out pocketing" of the lining of the urethra which can interfere with urinary flow or result in post-urination leakage. Strictures are narrowings in the urethra so severe that it obstructs the flow of urine.

Urethrostomy and excision of the external genitalia can also be done, which creates a permanent opening in the urethra. This is the most common way of treating the condition, as there are no adverse effects known. In dogs, the opening is usually made at the level of the scrotum. The male animal will squat to urinate, much like female dogs do. In cats, the opening is made just below the anus. Complications of the surgery include recurrent bladder infections, stricture of the urethrostomy site if the urethra was badly damaged, or bleeding of bright red blood which is very common due to the high level of blood supply in the urethra. The male animal will become infertile, if not already, as he has to be neutered at the time of the surgery. The owners may choose to not have any surgery done to correct the problem in cases of mild or even moderate severity. If the dog has urine scald dermatitis, the owners can treat it with frequent cleaning and topical ointment. Urine pooling in the prepuce can be treated by flushing the prepuce daily. This is something to be taken under extreme consideration due to the commitment on a daily basis.

In essence, hypospadias can be defined as an incomplete masculinization of the male animal due to the inhibition of testosterone during the fetal stage, often by means of the steroid receptors blocked. Although some owners may choose to have their animal live with this defect when it does not negatively affect their daily life, most of the time surgery is the best option. By making an urethral opening in a place where the animal may urinate freely and without any possible occurrence of urine scalding, this gives more freedom for the animal itself. Even though the animal will become infertile, this might be wise seeing as, although there have been no proven connection that hypospadias is genetic, breeding an animal with the condition might have adverse effects on the population at a later date.