Does your breeding stallion have a tinge of blood in his semen after a routine collection for artificial insemination? Or do you notice physical lesions on his genitalia during pre- or post-breeding washing? These are tell-tale signs of hemospermia—literally, blood in the semen—a condition that is not only detrimental to fertility, but can also negatively impact stallion welfare and industry economics.

Lisa Pearson, DVM, MS, Dipl. ACT, theriogenologist at Washington State University's College of Veterinary Medicine, reviewed the common causes and treatment options for stallions with this condition at the 2013 American Association of Equine Practitioners convention, held Dec. 7-11 in Nashville, Tenn.

Veterinarians typically diagnose hemospermia at the height of breeding season, when live cover or collection schedules are at their busiest.

"One of the mainstays of treatment for all cases is sexual rest, which has severe economic consequences on the stallion's reproductive performance," Pearson said.

Causes of this condition, however, vary, and Pearson discussed several of them during her presentation.

Squamous Cell Carcinoma

One of the most serious and potentially life-threatening causes of hemospermia is squamous cell carcinoma (SCC). These cancerous tumors can develop on a horse's penis and bleed due to irritation or ulceration during erection.

"SCC is commonly identified in horses with unpigmented genitalia but can occur in any breed or color," Pearson explained. "Appaloosa and American Paint horses are significantly more affected than other breeds."

SCC can develop on a horse's penis and bleed due to irritation or ulceration during erection.

Photo: Courtesy Drs. Lisa Pearson and Ahmed Tibary

She said most penile SCC is associated with equine papillomavirus-2, and that the lesions are varied, slow-growing, locally invasive, and metastasize (invade and spread to other parts of the body) late in the course of disease.

"Small lesions may be treated with chemotherapy (using intralesional cisplatin, topical 5-fluorouracil, or oral cyclooxygenase [type of enzyme] inhibitors), cryotherapy (cold therapy), or laser excision," Pearson said. "Large lesions may require surgical resection or a phallectomy (partial or complete surgical removal of the penis)."

Study results have shown varying levels of success using all these techniques; unfortunately, SCC has a high recurrence rate (up to 44%) regardless of the treatment method, Pearson said.

Urethral Rent

Urethral rents (tears to this conduit for urine and semen) can occur in stallions of any age or breed—although Quarter Horses are for some reason overrepresented, Pearson said. Hemospermia occurs when a rent hemorrhages during erection.

Urethral rents (tears to this conduit for urine and semen) can occur in stallions of any age or breed—although Quarter Horses are for some reason overrepresented.

Photo: Courtesy Drs. Lisa Pearson and Ahmed Tibary

"Treatment for urethral rent begins with sexual rest," Pearson said. "In some stallions, adequate sexual rest results in complete resolution of hemospermia and rent healing."

Other treatment options include subischial urethrostomy (a surgical procedure that creates an opening in the urethra) and laser coagulation (a type of laser surgery to seal or destroy blood vessels), but Pearson noted these have only been tried in a few animals.

Penile Habronemiasis

Penile habronemiasis, also known as summer sores, is uncommon in the United States due to widespread anthelmintic (dewormer) use that kills the causative Habronema spp. larvae flies deposit in open wounds. Thus, veterinarians should suspect horses with this condition to also have a large stomach worm population, Pearson said.

"Hemospermia results from collection from affected horses, with hemorrhage originating from inflamed or ulcerated areas of the glans penis," she explained.

Treatment includes avermectin anthelmintic administration followed by corticosteroids to reduce immune reaction. Pearson said proper parasite control programs, manure management, and fly control can help prevent penile habronemiasis from developing.

Equine Herpesvirus-3

"Infection with equine herpesvirus-3 (EHV-3) can lead to pustules and ulceration of the penile surface, which can result in hemospermia on erection and service of an artificial vagina or mare," Pearson said.

As with other causes of hemospermia, EHV-3 cases require sexual rest—not only to help the stallion's painful lesions heal, but also because the infection is highly contagious.

Seminal Vesiculitis

Seminal vesiculitis (inflammation of the seminal vesicles) is an important and probably underreported hemospermia-causing condition, Pearson said.

"Treatment options include systemic antibiotics and anti-inflammatories as well as endoscopic-assisted lavage (flushing) of the seminal vesicles."

Studies on recovery from and prognosis of this disease, however, are limited. "In some cases, resolution is possible," Pearson said. "In others, the reproductive management of the stallion is altered to reduce risk of transmission of pathogenic bacteria to mares and improve pregnancy rates."

Penile Injuries

Hemospermia can also be associated with several penile injuries, including damage to the urethral process from the mare's tail hairs during live-cover breeding as well as lacerations, swellings, or hematomas resulting from kicks.

"Sexual rest is indicated until the lesion is healed because hemorrhage may recur with subsequent mating or artificial vagina use," Pearson said.

Take-Home Message

"Practitioners who work with breeding stallions should educate stallion owners on the importance of routine breeding soundness examinations at the beginning of each breeding season and routine collection and semen cryopreservation of healthy stallions," Pearson concluded. "These practices will help to identify any pathology early, which can result in higher treatment success and survival rates, especially for SCC, and allow for frozen semen to be available for breeding if the horse requires sexual rest, thus preventing the loss of a foal crop."

She also emphasized the importance of referring affected horses to specialty centers if veterinarians are unable to treat them on the farm.

Disclaimer: Seek the advice of a qualified veterinarian before proceeding with any diagnosis, treatment, or therapy.

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