Physical Trauma

Stallions that must perform natural service will be at risk of trauma caused by the mare or from events associated with breeding. Poor footing in the breeding area may lead to musculoskeletal injuries that can limit the stallion’s mounting ability or result in psychological trauma or both. When a mare kicks a stallion during breeding, there may be damage to his external genitalia, resulting in swelling, edema, abrasions, or lacerations. Blunt trauma to the penis and sheath may cause enough swelling to prevent retraction of the penis into the sheath (paraphimosis). With the penis swinging free outside the sheath, normal blood circulation to the glans is inhibited, leading to further swelling and edema. In addition, abrasion of the penis will occur as the stallion moves about. Abrasions can rapidly progress to ulceration, and without aggressive therapy the stallion’s penis may require amputation because of irreversible damage.

The initial treatment consideration in the case of trauma should be stall confinement to prevent further damage. Second, the penis should be replaced into the stallion’s sheath. With minimal swelling, the penis may be easy to replace. When edema is extensive, the swelling should be reduced before replacement within the sheath is attempted. Application of a compression bandage beginning at the glans penis may decrease swelling sufficiently for replacement. With the penis inside the sheath, nonabsorbable sutures should be placed across the sheath opening. Retaining the penis in the sheath will allow return of normal blood circulation, reduce edema, and prevent further damage. The stallion can urinate without extending the penis. Urine scalding of the internal sheath may result, but its effect may be lessened with daily application of emollients.

If penile swelling cannot be reduced or the penis prolapses after the sheath has been sutured, then a sling should be fashioned to support the penis.² A sling can be fashioned from a bag used for laundering delicate fabrics. These bags are made from soft cotton material and provide support without damage to the penile tissues. The bag should be cut into a rectangle of the proper length and width to accommodate the penis. The penis is suspended in the soft cloth bag close to the ventral abdomen. The bag is held in place with 3-inch gauze straps attached to the corners and tied over the stallion’s croup. Several thicknesses of cotton beneath the gauze straps are necessary to prevent skin injury.

An alternative technique has been described using a plastic bottle that has been modified to be used as a preputial “splint.” A 1-liter saline bottle has the bottom cut out and the sharp edges padded with tape to prevent abrasions. The bottle is lubricated with petrolatum jelly and the opened bottom is inserted over the end of the penis, once it is reduced to a size that will fit inside the bottle. The neck of the bottle is used to anchor stint supports of long 2- or 3-inch gauze. Four stints are made, two pair to go laterally over the flank to the croup, and two to go caudally on either side of the prepuce and testicles and up between the legs skirting the tail-head to meet the lateral stints over the back, and are tied. The bottle top is left open for urine to be passed through. The splint is reset daily following hydrotherapy as needed and the penis monitored closely for any sign of abrasion caused by the retention device.

With the penis either supported as described or placed within the sheath, cold hydrotherapy should be provided for 20- to 30-minute intervals, two to four times daily. Such therapy may enhance local blood circulation, which decreases swelling and edema. Hydrotherapy should be continued as long as swelling and edema persist. Systemic administration of diuretics, glucocorticoids, and nonsteroidal anti-inflammatory drugs may be considered for reduction of edema but will not supplant the need for hydrotherapy and penile support. With full-thickness abrasion of the penile skin, systemic antibiotics are indicated to reduce bacterial contamination because secondary infections delay healing and promote swelling and edema.

Priapism is defined as penile erection in the absence of sexual stimulation that does not recede within a short period of time. The corpus cavernosum penis (CCP) is engorged with blood that soon develops fibrin and undergoes spontaneous clotting. The etiology is unclear but has been associated with the administration of phenothiazine tranquilizers, general anesthesia, neuromuscular dysfunction, equine herpesvirus infection, cachexia, dourine, and idiopathic. Early medical management consists of diuretics, nonsteroidal anti-inflammatory agents, manual massage, cold hydrotherapy, and suspension and support of the penis. General anesthesia and massage of the penis to decrease venous engorgement, application of a compressive elastic bandage, and lavage of the CCP using 10 to 12 gauge ingress and egress cannulas along with heparinized saline have all been described as useful when medical management is unrewarding or the value of the stallion warrants more aggressive therapy. When lavage is performed it is recommended to continue until arterial blood is flushed from the egress cannula. Several attempts to lavage or irrigate the CCP may be required for resolution. More aggressive surgical intervention may be considered by creation of a shunt between the CCP and the corpus spongiosum penis (CSP). Failure to aggressively manage and resolve this condition will lead to loss of the stallion as a breeding animal and may necessitate castration and phallopexy (Bolz technique).³

Trauma to the scrotum and testes may occur along with injuries of the penis and sheath. Scrotal and testicular injuries or edema require aggressive therapy to reduce the likelihood of permanent damage to the stallion’s fertility due to compromise of the thermoregulatory mechanism. With swelling, edema, or inflammation of the testes and scrotum, abnormal spermatozoa will be produced until normal heat exchange can be restored.

When the scrotum or testes are injured, ultrasonographic examination of the involved organs is beneficial to help determine the extent of damage. Testicular injuries could permit exposure of spermatozoa to the systemic circulation and result in antisperm antibody production. Antisperm antibodies can cause subfertility or sterility.

Stallions that experience genital injuries may develop psychological or behavioral abnormalities, scarring within the reproductive system, and immunologic changes as described. Such residual damage may not become apparent until the stallion is reintroduced to the breeding shed routine. Management should be cautioned about the likelihood of psychological or behavioral problems, or both, that may occur in injured stallions and should be encouraged to slowly and gradually introduce the stallion back into his former routine.

Hemospermia

Hemospermia causes infertility that may vary with the quantity of red blood cells in the ejaculate. The mechanism by which blood causes infertility has not been determined. Hemospermia may result from either external or internal lesions in the stallion’s reproductive organs. External lesions include those from traumatic injury such as lacerations, hematomas, abrasions, ulcerations, and dermatologic conditions. Lacerations and abrasions may occur during breeding, as when the mare’s tail hairs cut the glans or urethral process during coitus. Hematomas may rupture externally or into the urethra causing spontaneous bleeding or hemorrhage during urination or ejaculation. Ulcerations may arise from infectious disease lesions either externally or internally.

Internal urethral ulcerations lead to contamination of the ejaculate with blood because of rapid expansion and contraction of the tissues during urethral pulsations. The ulcers may be located anywhere from the urethral process to the pelvic urethra near the ejaculatory ducts. Spontaneous hemospermia can occur in stallions that are bred heavily, as a sequela to bacterial urethritis, from scar tissue that results from a stallion ring, or from infection of the accessory sex glands.

Diagnosis of hemospermia may begin by observation of accumulated dried or fresh blood on the stallion’s rear legs, sheath, or ventral abdomen. Fresh blood may be noted on the stallion’s penis following coitus or may be visible grossly in the collection container after semen collection. If fresh blood appears on the stallion’s penis following coitus, the source of hemorrhage could be from the mare’s genitalia (vaginal or hymen rupture, or trauma of a varicocele within the vestibule) or from the stallion. To determine the origin of blood, the mare must first be ruled out as a source, then the stallion’s penis and sheath should be examined with a small-diameter flexible endoscope, with care taken to prevent iatrogenic urethral trauma. The examiner should be cognizant that ulcers may occur anywhere along the urethra. The most frequent location for urethral ulcers may be in its pelvic portion as the urethra bends distally over the ischial arch, or near the ejaculatory ducts at the cranial termination of the urethra.

Treatment for hemospermia consists of sexual rest, local medications placed in the pelvic urethra via a perineal urethrostomy, systemic antimicrobial administration, acidification of the urine, or surgery (perineal urethrostomy). Laser surgery may be useful for cautery of the ulcer(s).