Defects in the urethral mucosa can cause hematuria and hemospermia in male horses.1,2 Such defects were first described as ulcerations in the proximal portion of the urethra in 4 horses with acute onset of hematuria.2 Since then, urethral rents have been identified as the source of hemorrhage.1 Typically, those rents are located on the convex surface of the urethra at the level of the ischial arch, are linear, extend into the corpus spongiosum, and can be observed during a urethroscopic examination.1 Clinical signs associated with urethral rents include the presence of blood in the urine of geldings or semen of stallions, and diagnosis is confirmed by visual observation of a mucosal rent in the proximal aspect of the urethra during urethroscopy. However, a urethral rent should be suspected as the cause of hematuria or hemospermia in male horses when examination has eliminated all other possible sites of hemorrhage even when a rent is not observed during urethroscopy.
In geldings, hematuria associated with a urethral rent generally becomes macroscopically evident during the terminal portion of urination, whereas in stallions, hemospermia associated with a urethral rent may be evident microscopically or macroscopically depending on the amount of blood in the ejaculate.1 Other causes of hematuria in male horses include the presence of calculi within any portion of the urinary tract,3–11 neoplasia of a kidney or bladder,12–14 pyelonephritis,15,16 ureteritis,5 cystitis,3 idiopathic hematuria,17 verminous nephritis,18 congenital or acquired vascular anomalies,19–21 cantharidin toxicosis,22 chronic or excessive NSAID administration,23 or exercise.23 Other reported causes of hemospermia in stallions include urethritis,24 seminal vesiculitis,25,26 and habronemiasis, trauma, or neoplasia of the urethral process or glans penis.1,27
Although the pathogenesis of urethral rents is unknown, the fact that they frequently develop at the ischial arch where the urethra narrows has led to speculation that the decrease in urethral diameter results in an increase in the hydrodynamic force to which that portion of the urethra is exposed during urination or ejaculation.28 Also, the lamina propria of the urethra may be thinner at the ischial arch than elsewhere. Because rents in the urethral mucosa communicate with the corpus spongiosum, a pressure increase in the corpus spongiosum, such as occurs during urination or ejaculation, results in hemorrhage into the urethral lumen. In geldings, the mean ± SE pressure in the corpus spongiosum during urination increases 2.4-fold from 11.3 ± 3.4 mm Hg to 27.5 ± 12.1 mm Hg, whereas that in stallions increases only 1.3-fold from 12.1 ± 2.8 mm Hg to 15.3 ± 3.3 mm Hg.28 This discrepancy in the magnitude of the pressure increase in the corpus spongiosum during urination between geldings and stallions is a function of the fact that the corpus spongiosum of geldings is less voluminous and not as well developed as that of stallions.28 In stallions, contraction of the bulbospongiosus muscle during ejaculation and coitus increases the mean ± SE pressure in the corpus spongiosum from 17 ± 1.4 mm Hg to 762 ± 106.8 mm Hg.29 The reason geldings with urethral rents frequently have overt hematuria, whereas stallions with urethral rents typically have only hemospermia, is likely associated with differences in the magnitude of the pressure increase within the corpus spongiosum during urination and ejaculation, coupled with the sudden decrease in intraluminal urethral pressure at the end of urination.28
Treatment of horses with urethral rents is aimed at decreasing pressure within the corpus spongiosum to minimize or prevent hemorrhage through the rent so that it can heal.1 Although sexual rest for stallions with urethral rents may alleviate hemospermia associated with an increase in corpus spongiosum pressure during ejaculation, they may still have overt hematuria during urination. Surgical options for the treatment of urethral rents include PU and CS. Both procedures can be performed in sedated horses restrained in a standing position following desensitization of the perineal region by administration of a caudal epidural or local anesthesia, and can also decrease the pressure within the corpus spongiosum during urination by the creation of a longitudinal defect in its caudal aspect that is left to heal by second intention. The 2 procedures are similar except that the CS incision extends into the corpus spongiosum only, whereas the PU incision extends into the urethral lumen. Following both procedures, hemorrhage caused by a pressure increase in the corpus spongiosum during urination is diverted from the urethral rent to the incision. Healing of the PU or CS is generally complete by 3 weeks after surgery,28 which is typically sufficient time for the urethral rent to likewise heal.
In a study30 of 18 stallions that were infertile because of hemospermia (of which only 1 stallion had a urethral rent), normal fertility was restored in 11 of 15 stallions that underwent PU and postoperative administration of nitrofurazone and hydrocortisone suppositories in the pelvic urethra. In a study1 of 8 male horses with urethral rents, PU resulted in long-term resolution of hematuria in all 6 geldings and long-term resolution of hemospermia in 1 of 2 stallions. A stallion with a urethral rent and recurrent hemospermia was successfully treated with a PU and application of a buccal mucosal graft to the urethral rent.31 In a study32 involving 2 geldings and 5 stallions with urethral rents, transendoscopic use of a neodymium:yttrium-aluminum-garnet or diode laser to fuse the edges of the rent was performed alone or in combination with a CS procedure. Hematuria or hemospermia was successfully resolved in 1 gelding and 4 stallions, respectively, that underwent laser treatment in combination with CS and in 1 gelding and 1 stallion, respectively, that underwent laser treatment only.32 The 4 stallions in which hemospermia was successfully treated with laser treatment and CS eventually returned to breeding, although 1 was later gelded for reasons unrelated to fertility or reproductive function.32 Hemospermia recurred in the stallion that underwent laser treatment only, and that horse was subsequently gelded.32
To our knowledge, the signalment, clinical features, and outcome for horses with urethral rents that underwent PU versus those for horses with urethral rents than underwent CS have not been described. Therefore, the objective for the study reported here was to describe the signalment, clinical features, and outcome for male horses with urethral rents that underwent PU or CS.
Materials and Methods
Case selection
The electronic medical record database for the Veterinary Teaching Hospital at Texas A&M University was searched to identify horses that were examined because of hematuria or hemospermia between 1989 and 2013. Geldings or stallions with hematuria or hemospermia that had a urethral defect identified during urethroscopic examination and subsequently underwent either PU or CS were included in the study.
Medical records review
For each gelding or stallion enrolled in the study, information extracted from the medical record included signalment, clinical signs of urinary or reproductive tract disease, urethroscopic findings, type of surgery performed, and response to surgery. Additionally, a summary of each stallion's breeding record was obtained from the appropriate breed association. The long-term outcome for each horse was determined on the basis of results of a standardized questionnaire that was administered to the owner, trainer, or referring veterinarian via telephone by one of the investigators (KGG or CEA) or a research assistant. A successful outcome for geldings was defined as resolution of hematuria, and a successful outcome for stallions was defined as resolution of hemospermia.
Procedures
All study horses underwent a urethroscopic examination to determine the source of hemorrhage. Semen was collected into an artificial vagina from each stallion immediately before urethroscopic examination to facilitate identification of a urethral rent. Each horse was sedated and restrained in a standing position in stocks. To prepare the horse for urethroscopic examination, the distal aspect of the penis was washed. The urethroscopic examination was performed with a flexible videoendoscope (diameter, 8.6 mm; length, 1 m), the insertion tube of which was sterilized prior to each use by immersion in 0.55% ortho-phthalaldehyde solutiona for 20 minutes and then rinsed with sterile isotonic saline (0.9% NaCl) solution.
Each horse underwent PU or CS in accordance with the preference of the attending clinician. Regardless of the procedure performed, horses were restrained in a standing position in stocks and sedated with xylazine hydrochloride (0.2 to 0.5 mg/kg [0.09 to 0.23 mg/lb], IV) or detomidine hydrochloride (0.01 to 0.02 mg/kg [0.0045 to 0.0091 mg/lb], IV) alone or in combination with butorphanol tartrate (0.01 mg/kg, IV). The perineal region was desensitized by the instillation of xylazine (0.15 to 0.2 mg/kg [0.068 to 0.091 mg/lb]) mixed with a 2% mepivacaine or lidocaine solution in a quantity sufficient to achieve a volume of 5 to 7 mL into the epidural space between the first and second coccygeal vertebrae. For some horses, the skin at the proposed incision site on the perineal raphe was desensitized by the SC instillation of a 2% mepivacaine or lidocaine solution in addition to, or in lieu of, epidural anesthesia. A urinary catheter was inserted into the urethra and passed in a retrograde manner until the tip was at the ischial arch. A 5- to 7-cm skin incision was made on the perineal raphe beginning 4 cm ventral to the anus. The incision was continued through the SC tissues, between the paired retractor penile muscles, through the bulbospongiosus muscle, and through the tunica albuginea surrounding the corpus spongiosum. For horses in which a PU was performed, the incision was continued through the corpus spongiosum and urethral mucosa into the urethral lumen. All incisions were allowed to heal by second intention.
All horses were administered tetanus toxoid, flunixin meglumine (1.1 mg/kg [0.5 mg/lb], IV), and 1 or more broad-spectrum antimicrobials, usually sulfamethoxazole-trimethoprim (30 mg/kg [13.6 mg/lb], PO, q 12 h) or procaine penicillin G (22,000 U/kg [10,000 U/lb], IM, q 12 h) and gentamicin (6.6 mg/kg [3 mg/lb], IV, q 24 h) before and after surgery. All stallions were sexually rested for at least 6 weeks.
Data analysis
Descriptive statistics were generated for the study population.
Results
Thirty-three horses (19 geldings and 14 stallions) met the inclusion criteria and were enrolled in the study, which represented 0.08% of all geldings and stallions admitted to the hospital during the study period. The study population had a mean age of 10 years (median, 10 years; range, 3 to 18 years). Breeds represented included American Quarter Horse (n = 26), American Paint Horse (3), Appaloosa (2), and Thoroughbred (2). The breed distribution for the study population reflected that for horses examined at the hospital. Nineteen geldings and 1 stallion were examined because of overt hematuria, and the mean duration of hematuria prior to examination was 56 days (median, 26 days; range, 4 to 180 days). Thirteen stallions were examined because of overt hemospermia, and the mean duration of hemospermia prior to examination was 193 days (median, 45 days; range 3 to 730 days).
Urethroscopic results indicated that all 20 horses with hematuria and 10 of 13 stallions with hemospermia had 1 urethral rent. Of the remaining 3 stallions with hemospermia, 2 each had 2 urethral rents and 1 had evidence of focal submucosal hemorrhage without a visible rent in the urethral mucosa (Figure 1). The urethral defect was present on the convex surface of the urethra near the level of the ischial arch in all 33 horses (Figure 2).
Urethroscopic image of the proximal portion of the urethra near the ischial arch in a 17-year-old Quarter Horse stallion that was examined because of hemospermia. Notice the focal area of submucosal hemorrhage (arrow) without overt evidence of a rent in the urethral mucosa. The stallion underwent CS for treatment of a urethral rent because no other source of hemorrhage could be identified as the cause of hemospermia and the focal area of hemorrhage indicated that the tunica albuginea surrounding the urethra was torn.
Citation: Journal of the American Veterinary Medical Association 249, 12; 10.2460/javma.249.12.1421
Representative urethroscopic image of a urethral rent (arrow) in a 12-year-old Quarter Horse gelding that was examined because of hematuria and subsequently underwent PU to divert hemorrhage from the rent and allow it to heal.
Citation: Journal of the American Veterinary Medical Association 249, 12; 10.2460/javma.249.12.1421
Of the 20 horses with hematuria, 13 underwent a PU and 7 underwent a CS. Of the 13 stallions with hemospermia, 7 underwent a PU and 6 underwent a CS. One stallion with hematuria that was initially treated with a CS had a relapse 2 years later and underwent a PU.
Information regarding the duration of postoperative antimicrobial administration was available for 32 of 33 horses. The mean duration of postoperative antimicrobial administration was 4 days (median, 3 days; range, 0 to 15 days). Stallions were sexually rested for a mean of 80 days (median, 60 days; range, 49 to 150 days) after surgery.
Long-term follow-up information was available for 17 of 20 horses with hematuria, of which 13 were treated with a PU and 4 were treated with a CS. The mean duration of follow-up for those horses was 1,570 days (median, 757 days; range, 40 to 6,813 days). All horses underwent only 1 surgical procedure for correction of hematuria. The long-term outcome was classified as successful for all 17 horses, although 1 gelding had a brief 2-day episode of hematuria 26 months after undergoing a PU that was not further investigated and resolved spontaneously.
Long-term follow-up information was available for 12 of the 13 stallions with hemospermia, of which 6 were treated with a PU and 6 were treated with a CS. Long-term follow-up information was not available for the remaining stallion because hemospermia recurred 6 weeks after it underwent a PU, and the owners elected to have it gelded at that time. The mean duration of follow-up for the other 12 stallions was 1,101 days (median, 768 days; range, 150 to 2,825 days). Ten stallions were treated by PU or CS alone, whereas the other 2 required primary closure of the urethral rent subsequent to the PU or CS. Long-term resolution of hemospermia was achieved in 7 (4 treated with a PU and 3 treated with a CS) stallions following the initial surgical procedure, and none of those 7 stallions developed postoperative complications.
Hemospermia recurred in 5 (2 treated with a PU and 3 treated with a CS) of the 12 stallions for which long-term follow-up information was available, including the 2 that underwent primary closure of the urethral rent subsequent to the PU or CS. One of those stallions had 2 urethral rents identified during the initial urethroscopic examination and underwent a CS. The hemospermia persisted even after the stallion had 8 weeks of sexual rest, and a second urethroscopic examination revealed that one of the urethral rents had not healed. A PU was performed, and primary closure of the rent was achieved by direct suturing through the PU with urethroscopic guidance (Figures 3 and 4). The urethral rent went on to heal without complication. The other stallion that underwent primary closure of the urethral rent initially had a PU performed, but hemospermia persisted for 4 months after surgery and a second urethroscopic examination revealed that the urethral rent was still present. Primary closure of the urethral rent was achieved by dissection through the perineal body and placement of a needle at the level of the urethral rent with urethroscopic guidance. A subischial PU was performed at the level of the rent. Briefly, a Foley catheter was passed through the PU into the urinary bladder. The proximal portion of the urethral rent was sutured with size-0 polyglactin 910 in a simple interrupted pattern, with the Foley catheter in place to ensure the patency of the urethra. The corpus spongiosum and perineal body were closed with size-0 polyglactin 910 in a simple interrupted pattern, and a Penrose drain was placed at the surgery site prior to skin closure. That stallion subsequently developed an incisional infection and ascending orchitis, and the infected testis was excised. At the time of follow-up (median duration after primary closure of the urethral rent, 711 days), hemospermia had not recurred in either stallion.
Urethroscopic image of a 7-year-old Thoroughbred stallion that was obtained during primary closure of a urethral rent by direct suturing through a PU incision. Notice the needle passing through the urethral mucosa (arrow). This stallion had 2 urethral rents identified during the initial urethroscopic examination and underwent a CS. Hemospermia persisted following the CS and 8 months of sexual rest, and a second urethroscopic examination revealed that one of the rents had failed to heal. The rent healed without complication following primary closure, and the hemospermia resolved and had not recurred at the time of follow-up (150 days after primary closure of the urethral rent).
Citation: Journal of the American Veterinary Medical Association 249, 12; 10.2460/javma.249.12.1421
Urethroscopic image of the stallion of Figure 3 that was obtained during primary closure of a urethral rent by direct suturing through a PU incision. Notice that the previously placed needle has been removed, and the suture can be seen passing through the urethral lumen (arrow). See Figure 3 for remainder of key.
Citation: Journal of the American Veterinary Medical Association 249, 12; 10.2460/javma.249.12.1421
Of the remaining 3 stallions in which hemospermia recurred, 1 developed 5 additional urethral rents and underwent 3 PU procedures over a 34-month period before long-term resolution of hemospermia was achieved. The stallion that had submucosal hemorrhage but no urethral rent visible during the initial urethroscopic examination and underwent CS had a recurrence of hemospermia 1 year after the surgery. When a second urethroscopic examination was performed, no evidence of urethral hemorrhage was identified, and the stallion did not undergo any other surgical procedures. The remaining stallion that developed recurrent hemospermia initially underwent a CS, which resulted in resolution of the condition for 1 breeding season. Hemospermia recurred during the second breeding season after the initial CS, and a PU was performed. The stallion was euthanized 2 days later because of a ruptured cecum.
Discussion
In the present study, the signalment, clinical findings, and outcome were described for 33 male horses with urethral rents that were examined because of hematuria or hemospermia. Urethral rents that extend into the corpus spongiosum can cause overt hematuria, which is most evident at the end of urination, and hemospermia in male horses. Although stallions with urethral rents are generally examined because of hemospermia, some may develop overt hematuria, as evidenced by 1 stallion of the present study. The presence of blood in the ejaculate has deleterious effects on the integrity of the cellular membrane and motility of sperm, which decreases fertility even though seminal quality may be unaffected otherwise.33,34
The mean duration from onset of clinical signs to examination was shorter for horses with hematuria (of which all but 1 were geldings) than for stallions with hemospermia. That finding was most likely associated with the fact that the horses with hematuria had overt clinical signs, whereas the stallions with hemospermia did not. Hemospermia is most frequently observed during the breeding season and is often detectable only by microscopic examination of a semen sample (most likely because of concerns about fertility). For some of the stallions in the present study, the delay between rent occurrence and treatment likely contributed to the difficulty in rent resolution.
For 1 stallion of the present study, urethroscopic examination revealed the presence of submucosal hemorrhage without a visible defect in the urethral mucosa, perhaps because the rent was too small to be observed. That stallion was treated for a urethral rent because no other source of hemorrhage could be identified as the cause of hemospermia, and the focal area of submucosal hemorrhage indicated that the tunica albuginea surrounding the urethra was torn.
Results of the present study were in agreement with those of another study1 in that PU or CS consistently provided long-term resolution of hematuria in male horses with urethral rents, but those surgical procedures alone did not always result in long-term resolution of hemospermia in stallions with urethral rents. Although 10 of 12 stallions with hemospermia in the present study were successfully treated with PU or CS alone, 3 of those 10 required multiple PU or CS procedures to achieve long-term resolution of hemospermia. In the remaining 2 stallions, long-term resolution of hemospermia was achieved only after primary closure of the urethral rent subsequent to the initial PU or CS.
In the present study, treatment of stallions with urethral rents and hemospermia appeared to be more difficult than treatment of geldings with urethral rents and hematuria. This was most likely a reflection of multiple factors, one of which is the frequency of spontaneous erection in stallions. In a study35 of 25 stallions, the mean incidence of spontaneous erection within a 24-hour period was 17.9 erections (range, 7 to 30 erections). Several stallions of the present study developed spontaneous erections frequently during the postoperative period. In fact, 1 stallion developed a spontaneous erection as frequently as once per hour, which caused hemorrhage through the PU and resulted in severe anemia.
The present study had several limitations that included a fairly small study population, an uneven distribution of horses between treatment modalities (20 horses underwent PU and 13 underwent CS), and the loss of some horses to follow-up. The small study population was a function of the low incidence of hematuria and hemospermia secondary to urethral rents in male horses during the observation period. However, the study population of the present study (n = 33 horses) was much larger than that of other reports1,30–32 in which the study population ranged from 1 to 8 horses. Horses were treated with either PU or CS at the discretion of the attending clinician, and because of the retrospective nature of the study, we had no control over how many horses underwent each procedure or how many were lost to long-term follow-up (4/33 [12%]).
Although male horses with hematuria or hemospermia that undergo PU for the treatment of urethral rents develop postoperative complications such as severe hemorrhage, cystitis, urethral fistula, and urethral stricture infrequently,36 those complications can be avoided by performing a CS. On the basis of our clinical experience, CS is as successful as PU for the treatment of male horses with hematuria subsequent to a urethral rent, and long-term resolution of hematuria in such horses is frequently achieved after only 1 procedure. However, stallions with hemospermia subsequent to a urethral rent may require more than 1 PU or CS procedure or primary closure of the rent to achieve resolution of the condition.
Acknowledgments
Supported by the Paula and Michael Gaughan Endowment and the Legends Premier Stallion Season Auction.
ABBREVIATIONS
| CS | Corpus spongiotomy |
| PU | Perineal urethrotomy |
Footnotes
CIDEX OPA, Advanced Sterilization Products, Irvine, Calif.
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