Eleven horses (6 geldings and 5 stallions) were evaluated at the Veterinary Medical Teaching Hospital of Texas A&M University for conditions requiring phallectomy from January 2007 through April 2009. Ten were American Quarter Horses, and 1 was a Thoroughbred. Ages ranged from 2 to 28 years (mean, 18.5 years; median, 20 years), and body weight ranged from 266 to 512 kg (585.2 to 1,126.4 lb). Four horses had body condition scores of 2/9, 1 horse had a score of 3/9, 3 horses had a score of 5/9, 2 horses had a score of 6/9, and 1 horse had a score of 7/9.1
Seven horses were brought to the hospital for treatment of chronic paraphimosis resulting from marked physical debilitation (2 geldings and 4 stallions) or trauma to the penis from a breeding accident (1 stallion). A gelding was admitted to the hospital for treatment of priapism that developed subsequent to administration of acepromazine, and 3 geldings were admitted for squamous cell carcinoma of the glans penis, urethral process, free portion of the penis, or a combination of these conditions. The stallion with paraphimosis secondary to a breeding accident also had bilateral non-septic orchitis.
None of the 7 horses with paraphimosis was able to retract the penis. Chronicity of the paraphimosis in 6 horses ranged from 2 weeks to 2 months and was unknown in the seventh horse. Horses with paraphimosis had been treated by hydrotherapy, application of an emollient salve, application of a tourniquet, and support of the penis against the ventral aspect of the abdomen by use of a sling. The horse with priapism secondary to acepromazine administration had developed the condition 2 days prior to referral and was treated once by intracavernosal administration of phenylephrine and irrigation of the cavernosal tissues. The 3 horses with squamous cell carcinoma of the penis had had the condition for 2 years and had been treated by repeated application of a cryogen or chemotherapeutic agent to the lesions.
The 5 stallions were teased to an ovariectomized mare at the hospital to ensure that each was incapable of achieving an erection. Whereas none of the stallions could achieve an erection, 2 did exhibit signs of a good libido. Penile disease of all 11 horses was considered intractable. Two debilitated horses were anesthetized at the hospital in an attempt to perform a traditional method of phallectomy, but the horses failed to maintain an adequate blood pressure and anesthesia was discontinued and surgery was not performed.
To avoid subjecting the horses in poor physical condition to general anesthesia (n = 6 horses) or because of financial restrictions imposed by the owner (5), the decision was made to perform a phallectomy, with each horse standing. The modified Vinsot technique of partial phallectomy was chosen because of its simplicity, compared with that for other techniques of partial phallectomy2
To prepare horses for the procedure, each received flunixin meglumine (1.1 mg/kg [0.5 mg/lb], IV), procaine penicillin G (22,000 U/kg [10,000 U/lb], IM), and tetanus toxoid (1 mL, SC) within 1 hour before surgery. Each horse was restrained in a set of stocks during the procedure. The tail was wrapped and reflected to the side of the horse with elastic gauze. The perineum and penis (and the scrotum, in stallions) were aseptically scrubbed with povidone-iodine soap and water. A subischial urethrostomy was performed when penile disease was evident just distal to the prepuce. A distal urethrostomy was performed between the preputial ring and preputial orifice when the penile disease was confined to the glans or free portion of the penis.
All horses were restrained with a twitch during the administration of local anesthetic. Two horses required sedation with xylazine HCl (0.5 to 1.0 mg/kg [0.23 to 0.45 mg/lb], IV). For horses that received a subischial perineal urethrostomy, the skin was desensitized by instilling 5 mL of 2% mepivacaine HCl SC on the perineal raphe approximately 2 to 3 cm ventral to the anus. The external portion of the penis was then desensitized with a subcutaneous ring block by use of 20 mL of 2% mepivacaine HCl, administered proximal to the site of partial phallectomy. Horses that received a distal urethrostomy received only a penile ring block. A stallion cathetera was inserted through the distal urethral orifice into the bladder to facilitate recognition of the urethra during the urethrostomy. When the horse was a stallion that required concurrent castration, 10 mL of 2% mepivacaine HCl was instilled SC in the ventral aspect of the scrotum on each side of the scrotal raphe and into each spermatic cord. Stallions were castrated following penile amputation by means of a half-closed technique.3
To perform a subischial urethrostomy, a 4-cm-long cutaneous incision was created on the perineal raphe, 2 to 3 cm from the ventral aspect of the anus. The incision was extended between the paired retractor penis muscles and through the bulbospongiosus muscle, the corpus spongiosum penis, and urethral mucosa overlying the stallion catheter. A permanent urethral stoma was created by suturing the urethral mucosa to the edge of the skin incision with simple interrupted sutures of 2-0 polyglyconate.b The more distal urethrostomy incision (approx 3 cm) was created in a similar fashion between the preputial ring and preputial orifice on the ventral aspect of the penis, approximately 1 cm proximal to the proposed site of penile amputation.
After creating the urethrostomy, the stallion catheter was removed and a tourniquet was applied several centimeters proximal to the proposed site of amputation by use of a bander castration toolc and specialized latex tubing.d The tourniquet consisted of tubing configured in a dual-loop pattern with a central metal clamp. One loop was attached to the bander instrument with the metal clamp positioned seam-side up. The remaining loop was then placed over the penis several centimeters proximal to the site of penile transaction (Figure 1). When a distal urethrostomy was performed, the band was placed 1 cm distal to the urethrostomy incision. The ratchet mechanism was tightened until the penile tissue underlying the latex tubing was maximally compressed. The metal clamp was then crimped to maintain tension on the loop, and the caudal loop was transected with a band cutter provided by the manufacturer of the bander device. The penis was simply transected 2 cm distal to the band, and no tissue closure was performed. No surgical complications were noticed in any horse. The 7 horses with paraphimosis and 2 of the horses with squamous cell carcinoma received a subischial, perineal urethrostomy because of the extent of penile damage extending close to the level of the preputial orifice. In the remaining 2 horses, a distal urethrostomy was performed between the preputial ring and preputial orifice.
Photograph showing placement of a tourniquet prior to partial phallectomy by use of a modified Vinsot technique in a 17-year-old Quarter Horse gelding.
Citation: Journal of the American Veterinary Medical Association 237, 1; 10.2460/javma.237.1.82
Photograph showing placement of a tourniquet prior to partial phallectomy by use of a modified Vinsot technique in a 17-year-old Quarter Horse gelding.
Citation: Journal of the American Veterinary Medical Association 237, 1; 10.2460/javma.237.1.82
Photograph showing placement of a tourniquet prior to partial phallectomy by use of a modified Vinsot technique in a 17-year-old Quarter Horse gelding.
Citation: Journal of the American Veterinary Medical Association 237, 1; 10.2460/javma.237.1.82
The tubing was left in situ to produce necrosis of penile tissue distally. The site of amputation was left to heal by second intention after the tubing and necrotic segment of penis distal to it sloughed (Figure 2). None of the horses developed hemorrhage at the site of amputation, stranguria, or dysuria after surgery. Two horses had mild hemorrhage from the perineal urethrostomy at the end of each urination for 1 day after surgery. None of the horses had hemorrhage associated with the site of penile amputation. All horses appeared comfortable; rectal temperature, pulse rate, and respiration rate were all within reference limits during hospitalization.
Photograph of ischemic necrosis 7 days after band placement in a 2-year-old Quarter Horse stallion that underwent partial phallectomy by use of a modified Vinsot technique.
Citation: Journal of the American Veterinary Medical Association 237, 1; 10.2460/javma.237.1.82
Photograph of ischemic necrosis 7 days after band placement in a 2-year-old Quarter Horse stallion that underwent partial phallectomy by use of a modified Vinsot technique.
Citation: Journal of the American Veterinary Medical Association 237, 1; 10.2460/javma.237.1.82
Photograph of ischemic necrosis 7 days after band placement in a 2-year-old Quarter Horse stallion that underwent partial phallectomy by use of a modified Vinsot technique.
Citation: Journal of the American Veterinary Medical Association 237, 1; 10.2460/javma.237.1.82
Antimicrobials and anti-inflammatories were not administered postoperatively. Eight horses remained in the hospital for 24 to 48 hours before being discharged. In 3 horses, the procedure was performed on an outpatient basis. Hospitalized horses underwent a complete physical examination every 12 hours, in addition to monitoring for hemorrhage from the surgical sites and signs of discomfort, stranguria, dysuria, and hematuria. Following discharge from the hospital, owners were instructed to monitor the penile stump for the presence of the tubing, discharge at the site of amputation, the presence of blood in the urine, and healing of the surgical sites. Owners were also instructed to confine the horses to a small paddock for 30 days. Horses that were gelded were isolated from mares for 30 days. Owners of horses that were physically debilitated received instructions regarding nutrition, anthelmintic treatment, and dental care.
Follow-up data were available for all 11 horses via telephone contact with the owners. Owners were specifically asked about when the tourniquet fell off, the cosmesis of the amputation site, and whether their horse developed stranguria, hematuria, urine scalding, or a fistula at the amputation site. Of these 11 horses, 1 was euthanatized 2 weeks after surgery for an unrelated problem (ie, a fractured limb). Follow-up data from the other 10 horses were obtained 27 to 752 days (median, 454 days) after surgery. The owners reported that all horses were comfortable at home following surgery, including those horses that underwent partial phallectomy on an outpatient basis. The owners reported that the tubing used as a penile tourniquet and the tissue distal to it detached between 3 and 4 weeks after surgery. The horses developed minimal purulent drainage from the site of penile amputation during this time. Owners reported that the reconstructed end of the penis had a good cosmetic appearance after it healed. All horses maintained patency of the urethrostomy site and had no evidence of leakage of urine from the site of amputation. Two of the 5 stallions that were castrated at the same time the penis was amputated developed scrotal swelling 3 days after surgery that necessitated manual opening of the scrotal incisions to allow for ventral drainage. The horse with priapism that received a distal urethrostomy developed mild urine scalding of the hind limbs that gradually diminished as the horse learned to posture to urinate. The stallion that received a perineal urethrostomy because of paraphimosis secondary to breeding trauma developed moderate scalding of the tail attributable to a reluctance to lift its tail during urination. Scalding in that horse had not diminished in the postoperative period.
Discussion
Indications for partial phallectomy in horses include chronic paraphimosis (either primary or secondary to priapism; debilitation; drug-induced paralysis; traumatic injury, such as from a breeding accident; or systemic disease), neoplasia that is too extensive to allow local treatment or does not respond to treatment, and stenosis of the distal aspect of the urethra.4–7 Partial phallectomy is generally regarded as a salvage procedure in stallions and is commonly performed with the horse anesthetized to facilitate surgery.2 Techniques of partial phallectomy include those of Vinsot,8 Williams,9 and Scott,10 which are used to amputate various lengths of the free portion of the penis. Horses with more extensive lesions involving the internal preputial lamina require a phallectomy with en bloc resection with or without penile retroversion.11,12
Partial phallectomy and regional anesthesia of the penis in standing horses has been reported11,13 and can be useful for horses that are a poor candidate for general anesthesia or for horses with owners that have imposed financial restrictions that do not allow for the expense of general anesthesia. Regardless of technique used, the technical challenges of partial phallectomy involve compressing the corporeal tissue immediately proximal to the penile transection site and creating a new urethral orifice. Complications of partial phallectomy include hemorrhage from corporeal tissue with potential disruption of the compression sutures, edema resulting in acute urinary obstruction, and urethral stricture.14,15 Intermittent hemorrhage at the end of urination is expected postoperatively and may persist for up to 5 weeks before it resolves spontaneously.14 The outcome of horses that have undergone partial phallectomy while anesthetized is good,14,15 but to our knowledge, only 1 report11 exists of partial phallectomy performed with the horse standing.
The modification of the Vinsot technique of partial phallectomy we made differed from the originally described technique8 in the material used as a penile tourniquet, the shape and location of the site of urethrostomy, its use in standing horses, and the concurrent castration of stallions. In the original description of the technique, large, nonabsorbable suture material was used for a penile tourniquet. Umbilical tape (3/8 inch) has also been historically used to compress the corporeal tissue. In this report, the bander castration device with a latex loop was used to maintain continuous and maximal pressure on the underlying penile tissues, thereby preventing hemorrhage from the corporeal tissue. When used with appropriate local anesthesia, the tourniquet did not appear to cause discomfort to any of the horses in this report, either at the time of surgery or in the postoperative period. The horses did not have any increase in heart or respiratory rates postoperatively. None of the secured tubing dislodged prematurely.
With the modified Vinsot technique of partial phallectomy, the urethrostomy can be performed in the subischial area or between the preputial ring and preputial orifice, depending on the extent of penile damage. Eight of the horses in our study had disease that was evident up to the level of the preputial orifice. By placing the urethrostomy in the subischial location, we were able to amputate a greater portion of the penis than would be possible with the techniques of Williams, Scott, or Vinsot. In addition, the first author found that the subischial urethrostomy was easier to perform than the distal urethrostomy and potentially safer because veterinarians do not need to work beneath a horse's abdomen. An additional benefit to the subischial urethrostomy site may include a decrease in the risk of urethral obstruction due to the presence of postoperative edema resulting from placement of the tubing in proximity to the urethrostomy site.
In the Vinsot method, a triangular urethrostomy is created on the ventral aspect of the penis by removing a portion of the skin, subcutaneous tissue, bulbospongiosus muscle, and corpus spongiosum penis. It is proposed that removal of this tissue would create a larger stoma that would be less likely to form a stricture. In our modified method, a linear incision was made through these same tissues without resection. None of the horses in the present report developed stricture of the urethrostomy site, and the horses had markedly less hemorrhage associated with urination in the postoperative period, compared with horses that have undergone traditional methods of phallectomy. In addition, the poor body condition of horses that had paraphimosis secondary to extreme physical debilitation simplified the creation of a subischial, perineal urethrostomy (ie, the urethral mucosa was easily sutured to the skin to create a permanent stoma because of the degree of muscle atrophy). Creating a linear urethrostomy, either in the subischial region or on the free portion of the penis, did not result in a urethral stricture in any horse.
The development of a standing method of penile amputation is useful in horses that are not good candidates for general anesthesia or for whom financial restrictions preclude general anesthesia. Five of the horses in this study were severely debilitated. Horses with such poor body condition typically do not tolerate the stress of general anesthesia well. In fact, 2 of the debilitated horses in this study were actually anesthetized in an attempt to perform a traditional method of phallectomy but were unable to maintain adequate blood pressure and recovered from anesthesia prior to performing surgery. This procedure was developed as an alternative method of phallectomy for use in standing horses because of these 2 cases.
Horses that have undergone partial phallectomy in which previously described methods were used often have moderate to marked hemorrhage from the penile amputation site during urination. Other studies have revealed that 83% of horses have postoperative hemorrhage,14 and in rare instances, these horses may require a second surgery to control bleeding.15 Hemorrhage is believed to originate from the corporeal bodies, particularly the corpus spongiosum, despite the placement of compression sutures. The horses that underwent this modified procedure had no hemorrhage from the amputation site. Only 1 horse in our study, the stallion that incurred paraphimosis due to breeding trauma, had postoperative hematuria. The site of hemorrhage in that horse was the perineal urethrostomy rather than the site of amputation, and the bleeding occurred only in the first 12 hours postoperatively and was minimal. The lack of hemorrhage with this modified surgical technique is a considerable improvement over techniques reported previously.
Two horses in the study had urine scalding postoperatively. The horse with priapism that received a distal urethrostomy learned to posture during urination in a manner that nearly eliminated urine scalding. However, the stallion that received a subischial urethrostomy never learned to lift its tail during urination and continued to scald the hair on its tail. Urine scalding of the skin of the perineum did not occur. None of the horses had leakage of urine from the penile amputation site.
Traditionally, it has been recommended that sexually intact horses be castrated 3 to 4 weeks prior to phallectomy.2 Theoretically, the time delay between the castration and phallectomy would allow for a reduction in circulating testosterone and therefore stallionlike behavior. This would reduce the risk of a horse achieving an erection and disrupting the compression sutures in the cavernosal tissue. In the present study, all 5 stallions were castrated immediately following phallectomy. It should be considered that these stallions had chronic paraphimosis and were physically unable to achieve an erection when teased to a spayed mare. Two of the stallions developed edema of the prepuce and scrotum that required manual opening of the castration incisions to establish ventral drainage. Although this can be a common postcastration complication, we were initially reluctant to aggressively exercise horses because of concern regarding potential disruption of the penile tourniquet. Having gained further experience with the procedure, we are confident that routine exercise of horses after castration will not affect tubing placement.
Follow-up data on the horses in this study were obtained via telephone calls to the owners. One horse was returned to our hospital for a follow-up examination 30 days postoperatively. This horse had paraphimosis due to debilitation and had received a perineal urethrostomy and partial phallectomy during its first hospital admission. At reexamination, it was observed that the penile amputation site had formed an adhesion to the internal lamina of the external preputial fold. Endoscopy of the urethra was performed, and the amputation site appeared completely healed. There was little accumulation of urine within the urethra distal to the urethrostomy site. It appeared that, during the process of healing, adhesions formed between the penile amputation site and sheath, resulting in phimosis. In this horse, the phimosis was of no important consequence. This may not have been the situation had a distal urethrostomy been performed.
The modified Vinsot method negated the need for sophisticated or costly surgical equipment. The bander device was purchased from the manufacturer for approximately $250. The other instrumentation consisted of a urinary catheter and common surgical instruments. In our hospital, the cost of the modified procedure is approximately one-tenth that of a traditional phallectomy performed with a horse anesthetized. The development of this technique has provided options for owners who could not have afforded surgery involving general anesthesia.
The bander device has been used extensively to castrate immature and mature bulls and is reported to be humane and well tolerated when used with local anesthesia.16 The owners of the horses in this case series had experience with the bander for use in the emasculation of calves and bulls; however, other horse owners without such experience may require assurance that its use in this method of phallectomy is humane and effective. Owners should be made aware that the tubing and portion of the penis distal to it will slough, and complications may include mild bleeding from the perineal urethrostomy site and urine scalding. Potential for premature detachment of the tubing and subsequent hemorrhage from corporeal tissues remains a concern, but this complication did not develop in the horses in this report.
Stallion catheter, Jorgensen Laboratories, Loveland, Colo.
2-0 polyglyconate, Ethicon, Somerville, NJ.
Callicrate Bander, No-Bull Enterprises, St Francis, Kan.
ES-10, No-Bull Enterprises, St Francis, Kan.
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