Chapter 61 - Penis and prepuce II surgery Flashcards
What is a common cause of genital squamous cell carcinoma in horses?
Lack of pigmentation, particularly in older geldings or stallions.
What is hypospadias?
A congenital defect where the urethral meatus is abnormally located.
What conditions may accompany hypospadias in horses?
Chordee, incomplete prepuce, and meatal stenosis.
How is hypospadias in horses usually managed if it causes discomfort?
By amputation of the malformed penile portion.
What type of intersex condition is common in horses?
Male pseudohermaphroditism.
How can a pseudohermaphrodite horse’s appearance be altered?
By amputation or repositioning of the genitalia.
What is the most frequent neoplasm of the horse’s external genitalia?
Squamous cell carcinoma.
What factors might predispose certain horse breeds to genital carcinoma?
Nonpigmented genitalia and chronic irritation from smegma.
What virus is associated with genital squamous cell carcinoma in horses?
Equus caballus papillomavirus type 2 (EcPVpv2).
What are common symptoms of advanced squamous cell carcinoma in horses?
Ulceration, necrosis, and possibly a malodorous discharge.
What type of laser is used to excise squamous cell carcinoma on the external genitalia?
Carbon dioxide laser.
What is a potential benefit of using a laser for excision over traditional methods?
It reduces postoperative swelling and has a thermal killing effect on marginal tumor cells.
What surgical procedures may be necessary for horses with extensive neoplastic lesions on the genitalia?
Preputial reefing or partial phallectomy.
What is the last-resort surgical procedure for extreme cases of neoplastic lesions?
Prescrotal urethrostomy with en bloc resection.
What material is typically used in cryotherapy for squamous cell carcinoma?
Liquid nitrogen or CO₂.
What is the ideal freezing and thawing cycle in cryotherapy for the best results?
A double, fast freeze–slow thaw cycle.
Which topical drug is used for small genital lesions in horses?
5% 5-fluorouracil.
How often is 5-fluorouracil applied to lesions?
Every 14 days.
What intratumoral chemotherapy drug is used in combination with surgery for squamous cell carcinoma?
Cisplatin.
Why is debulking a tumor before chemotherapy beneficial?
It lowers the tumor burden, making remaining cells more responsive to cisplatin.
What side effect is avoided by administering cisplatin directly into the tumor bed during surgery?
There is no detrimental effect on wound healing.
What treatment technique uses electrical pulses to improve drug delivery to neoplastic cells?
Electrochemotherapy.
What effect does electroporation have on cisplatin efficacy?
It can increase cytotoxicity up to 70 times in vitro.
What percentage of blood flow reduction occurs in tumors post-electroporation, aiding drug retention?
60–70%.
What is the maximum tolerated dose of doxorubicin for horses?
75 mg/m².
What medication is used alongside doxorubicin to minimize hypersensitivity reactions?
Antihistamines and nonsteroidal anti-inflammatory drugs.
At what temperature is the tumor heated during radiofrequency-induced hyperthermia?
50°C for 30 seconds.
What type of tumors in horses is hyperthermia commonly used for?
Sarcoids and ocular neoplasia.
What percentage of horses survived 18 months post-surgical therapy for genital carcinoma?
64.5%.
How does invasion of the cavernous tissue by carcinoma affect prognosis?
It indicates a poor prognosis due to higher metastatic potential.
What should be performed to detect abdominal metastases in cases of corporeal invasion?
Laparoscopic examination.
What is the main cause of cutaneous habronemiasis?
Larval infection by Habronema worms.
Where do these larvae typically cause lesions?
Prepuce and urethral process.
Which season sees higher incidence of habronemiasis?
Spring and summer.
What two immune reactions are associated with habronemiasis?
Granulomatous reaction and hypersensitivity.
What are common treatments for habronemiasis lesions?
Ivermectin and corticosteroids like prednisolone. Orally at 200 μg/kg, Prednisolone, administered orally at 1.5 mg/kg SID for 10 to 14 days, or diethylcarbamazine, administered orally at 1.5 mg/kg BID for 7 to 14 days
What condition causes blood in the ejaculate of stallions?
Hemospermia.
What commonly causes hemospermia related to the urethra?
Urethral rents.
What is a potential diagnostic tool for urethral rents?
Endoscopy.
What is a non-surgical treatment recommended for hemospermia?
Sexual abstinence.
What is the surgical method used to decrease pressure in the urethral lumen?
Perineal urethrotomy.
What alternative surgical procedure can be performed to treat hemospermia without exposing the urethral lumen?
Corpus spongiotomy.
What is a potential cause of hemospermia that might be detected in semen microscopically?
Septic seminal vesiculitis.
What technique may confirm bacterial seminal vesiculitis?
Transrectal ultrasonographic examination.
How might hemospermia related to bacterial urethritis be treated locally?
Topical application of antimicrobial drugs.
What surgical approach might restore preputial function affected by habronemiasis?
Elliptical resection of fibrotic areas.
What other diagnostic tx beside endoscopy is used for diagnosis of urethral rents?
Urethrography - the penis is radiographed after injecting 180 mL of barium suspension into the urethra. The barium is allowed to drain, 180 mL of air is injected to provide double contrast, and the penis is again radiographed.
In severe cases of habronemiasis affecting urination, what procedure is performed?
Amputation of the urethral process.
Figure 61-14. Hypospadias of the stallion in Figure 61-13 was accompanied by chordee, or an abnormal ventral curvature of the penis. Chordee caused this stallion to develop urine-induced dermatitis and discomfort during urination
Figure 61-13. Hypospadias of a stallion. The urethral meatus is located subcoronally and the internal lamina of the prepuce is complete. The stallion also had chordee
Figure 61-15. Perineal hypospadias in a 6-month-old colt. The colt is anesthetized and in dorsal recumbency
What COX inhibitor has been tried for metastatic squamous cell carcinoma?
Piroxicam.
What enzyme is associated with promoting metastasis in squamous cell carcinoma?
Cyclooxygenase-2 (COX-2).
What is a newly available generic chemotherapy drug for equine neoplasia?
Doxorubicin.
What anatomical structures can be sources of hematuria?
Kidney, ureter, bladder, urethra, or reproductive organs.
List three common causes of hematuria.
Renal calculi, vesicular neoplasia, pyelonephritis.
What is terminal hematuria, and what does it indicate?
Hematuria occurring at the end of urination; suggests a lesion at the proximal urethra or trigone of the bladder.
In which group is a urethral rent observed more frequently, stallions or geldings?
Geldings.
What anatomical feature might predispose horses to urethral rents at the ischial arch?
The sharp bend and narrow diameter of the urethral lumen at the ischial arch.
What anatomical feature might predispose horses to urethral rents at the ischial arch?
The sharp bend and narrow diameter of the urethral lumen at the ischial arch
Explain the effect of hydrodynamic forces on urethral rents at the ischial arch.
Increased hydrodynamic forces at the ischial arch can cause urethral damage due to high pressure on the thin lamina propria
What role does the corpus spongiosum (CSP) play in urethral hemorrhage?
CSP pressure may lead to bleeding through a urethral rent, especially as it remains high when urethral pressure drops.
Why is terminal hematuria less common in stallions than geldings?
CSP pressure in geldings is almost double that in stallions due to differences in cavernosal space volume.
Describe a characteristic finding on endoscopic examination of a urethral rent.
A 5-10 mm linear defect on the convex urethral surface near the ischial arch without inflammation.
What surgical technique is often used to treat urethral rents causing hematuria?
Perineal urethrotomy.
How does perineal urethrotomy treat hematuria?
By reducing vascular pressure in the CSP, preventing blood leakage through the rent.
What is corpus spongiotomy, and how does it compare to urethrotomy?
Incision into CSP without urethral penetration; as effective as urethrotomy in resolving hematuria
Horses affected with hemospermia caused by septic seminal vesiculitis should receive
antimicrobial therapy that is effective against the causative organism.
Figure 61-18. Massive granuloma on the internal preputial lamina caused by cutaneous habronemiasis. This mass was removed by segmental posthetomy.
Figure 61-32. Urethrotomy. A vertical incision has been created on the perineal raphe ventral to the anus. This incision extends through the skin and the paired retractor penis muscles, exposing the bulbospongiosus muscle. A vertical incision through this muscle and the underlying corpus spongiosum penis and urethral mucosa exposes the urethral lumen.
Figure 61-22. (A) Bolz technique of phallopexy. A 10-cm incision is made on the perineal raphe just caudal to the scrotum. (B) The penis is bluntly separated from surrounding fascia, taking care to avoid damaging the surrounding large pudendal vessels. (C) The penis is retracted until the attachment of the internal preputial lamina onto the free body of the penis is visible at the cranial extent of the incision. The penis is fixed in this position with two heavy nonabsorbable percutaneous sutures. The sutures, one each side of the penis, are inserted through the attachment of the internal preputial lamina. (D) The sutures are tightened until the glans penis is flush with the preputial orifice and are tied over rolls of gauze or large buttons to prevent the suture from cutting through the skin. The subcutaneous tissue and skin are closed separately.
Figure 61-23. This urethral process was amputated to eliminate hemospermia caused by carcinoma of the urethral mucosa. The urethral process was stretched with tissue forceps, and two small-gauge needles were placed through the urethral process and the catheter at right angles to each other, proximal to the diseased portion of the urethral process, to anchor the urethral process to the catheter.
Figure 61-24. Vinsot technique of phallectomy. A triangular section of tissue is removed from the ventrum of the penis proximal to the proposed site of transection, taking care not to enter the urethral lumen. The exposed urethra is incised on its midline from the base to the apex of the triangle, and the incised edges of the urethra and the triangle’s epithelial border are apposed with absorbable sutures in a simple-interrupted pattern. A nonabsorbable ligature is placed around the penis distal to the apex of the triangle, and the penis is severed distal to the ligature.
Figure 61-25. A bander castration device (Callicrate Bander) with a latex loop (ES-10) can be applied to the penis slightly proximal to the site of transection to prevent hemorrhage from the penile stump after partial phallectomy
Fig 1: Illustration of the main stages of the surgical procedure: (a) Creation of a perineal urethrostomy.
Fig 1: Illustration of the main stages of the surgical procedure: (b) Application of a Callicrate
Loop using the Callicrate Bander, approximately 2–3 cm proximal to the intended site of partial phallectomy
Fig 1: Illustration of the main stages of the surgical procedure: (c) Transection of the
penis and prepuce distal to the Callicrate Loop
Figure 61-26. When performing a partial phallectomy using the Vinsot technique, the surgeon can leave the transected end of the penis unsutured to heal by secondary intention. To prevent hemorrhage from the corporeal bodies, a tightly fixed nonabsorbable ligature is placed around the penis 2 to 3 cm distal to the newly created stoma, before the penis is transversely severed 1 to 2 cm distal to the ligature. The ligature used to compress the stump of the penis of this horse was a latex loop applied with a bander castration device, both of which are shown in Figure 61-25.
Figure 61-27. Rather than removing a triangle of tissue overlying the urethra, as is done when using the Vinsot technique of partial phallectomy, a permanent urethral stoma can be created more simply by making a 3- to 4-cm longitudinal incision into the catheterized urethral lumen. The margin of the urethra is sutured to the margin of the incision in the integument. These sutures should incorporate the corpus spongiosum penis. This stoma is being created proximal to the site of amputation and distal to the preputial orifice. A Babcock forceps grasps the urethral catheter.
Figure 61-28. (A) Williams technique of phallectomy. A triangle is removed from the ventrum of the penis. The triangle’s apex is directed proximad. The urethra is split on its midline from the base to the apex of the triangle, and the edges of the urethra and the triangle’s epithelial edges are apposed with simple-interrupted absorbable sutures. (B) Before closing the stump, the transected edge of the corpus spongiosum penis at the base of the triangle can be compressed with a simple-continuous absorbable suture line through the urethral mucosa and tunica albuginea. (C) The stump is closed with interrupted sutures that pass through the urethra, the tunica albuginea of the urethral groove, and the tunica albuginea of the dorsum of the corpus cavernosum penis and the penile or preputial epithelium. The sutures should be preplaced at equidistant intervals for an even closure. (D) The sutures are tightened and tied, compressing the cavernous spaces, and the integument is apposed to the urethral mucosa.
Figure 61-29. Scott technique of phallectomy. (A) A circumferential transverse incision through the epithelium of the body of the penis or prepuce is made at the intended site of transection. Dissection is continued through the corpus cavernosum penis (CCP) to the urethral groove. The corpus spongiosum penis (CSP) is circumferentially incised to the urethra, and a 4- to 5-cm segment of urethra is dissected free from the amputated section of penis. (B) The stump of the CCP is closed by apposing the outer perimeter of its tunica albuginea to the tunica albuginea of the urethral groove with interrupted absorbable sutures preplaced at equidistant intervals. (C) The sinusoidal spaces of the CSP are closed by suturing the tunica albuginea surrounding the CSP to the submucosa of the urethra with interrupted or continuous absorbable sutures. (D) The urethral stump is stretched and folded back over the end of the penis, where it is sutured to the penile or preputial epithelium and underlying tunica albuginea.
Figure 61-30. En bloc resection of the penis. (A) Four centimeters of urethra is left beyond the penile stump. (B) The position of the penile stump when retroverted is demonstrated. (From Markel MD, Wheat JD, Jones K. Genital neoplasms treated by en bloc resection and penile retroversion in horses: 10 cases 1977–1986. J
