19. Equine Penile Surgery

What is evaluated on clinical exam that might suggest that penile surgery is needed?

- Observe urination

- Visual examination

- Sedation

- Pudendal nerve block

-Palpation

- Endoscopy

- Ultrasonography

What are the sedation agents that should be avoided in stallions?

avoid phenothiazine derivative

tranquilizers in stallions

What are some disorders that can cause penile issues?

- Injuries

- Paraphimosis

- Phimosis

- Priapism

- Intersex

- Habronemiasis

- Neoplasia

What is the most common reason that penile surgery in horses is needed?

Injuries

What are the clinical signs of injury to the penis?

- Generalized swelling/cellulitis

- Hematoma formation

If there is "fracture of the penis", what does this mean?

Rupture of corporeal body (CCP)

What can rupture of the corporeal body lead to?

Lead to shunts and inability to achieve erection

What is caused by trauma, castration, debilitation or exhaustion, paralysis of retractor penis mm., phenothiazine derivative tranquilizers and leads to edema formation that prevents RETRACTION?

Paraphimosis

T/F Paraphimosis can cause the tissue to become excoriated, leading to balanoposthitis

True

What is the treatment for Paraphimosis?

- Control edema

- Hydrotherapy

- Emollient application and frequent massage

- Prevent further trauma

- Return to prepuce if possible or support against abdomen

- NSAIDs

- Surgical intervention

What are the THREE surgical interventions that are used to treat Paraphimosis?

- Segmental posthetomy

- Bolz phallopexy

- Phallectomy

What is the inability to protrude the penis and it is acquired stricture of preputial orifice or cicatrizing lesions of the preputial ring?

Phimosis

What is the treatment for Phimosis? (2)

- Wedge resection of preputial lamina or preputial ring

- Segmental posthetomy (reefing)

What is the persistent erection when penis fails to detumesce and it is usually related to administration of phenothiazine-derivative tranquilizers, especially to

stallions?

Priapism

What is the treatment for Priapism?

medical therapy, phenylephrine injection into CCP, saline irrigation of CCP, surgical shunt creation between CCP and CSP

What is it called when there is an anomaly of external genitalia development?

Intersex

Most of the intersex horses are typically what?

male pseudohermaphrodite

What structures do male pseudohermaphrodite have? (3)

-Rudimentary penis and prepuce which resembles an enlarged clitoris and vulva

- Genitalia positioned between ishchial arch and ventral abdomen

- Displays masculine behavior

In male pseudohermaphrodite, where are the testis usually retained?

Testis abdominally or inguinally retained

What is the treatment for an intersex horse?

castrate 4-6 weeks before

reconstructive surgery

What is caused by the cutaneous migration and encystment of Habronema (eq. stomach worm)?

Habronemiasis ("summer sore" or granular dermatitis)

What does Habronemiasis ("summer sore") look like clinically?

- Granulomatous reaction w/small yellow granules

- Local hypersensitivity reaction

- Pruritic

Where are the common predilection spots on the horse for summer sores?

Urethral process and preputial ring

What is a DDX for Habronemiasis?

SCC

What is the treatment for Habronemiasis?

- Larvicide [Ivermectin (0.3 mg/kg PO), organophosphates topically, orally, intravenously]

- Corticosteroids

- Surgical resection of preputial lesions, amputation of urethral process

T/F The penis is a common site for neoplasia especially in older horses that are non-pigmented

True

What are the common neoplasia of the penis?

Squamous papillomas, squamous cell

carcinomas, sarcoids, melanomas

What neoplasia is found on the glans or internal preputial lamina most commonly ?

SCC

What are the treatments for neoplasia of the penis?(4)

Surgical

Cryotherapy

Chemotherapy

Hyperthermia

What are the surgical options for removal of neoplasia?

- Segmental posthetomy (reefing)

- Partial phallectomy

- En bloc resection

What is the prognosis of neoplasia of the penis?

Good with early detection and treatment

Poor following spread to regional lymph nodes

What surgical procedure is good for superficial lesions and can salvage penis?

Segmental posthetomy

How is a Segmental posthetomy preformed?

- Catheter and tourniquet placed

- Circumferential incisions created

- Cuff of integument dissected avoiding large superficial vessels

- Meticulous hemostasis essential

- Closed in two layers with 2-0 absorbable suture

What is the THREE indicatiosn for using Vinsot technique?

- Paraphimosis (7)

- SCC (3)

- Priapism (1)

T/F Linear urethrostomy used and well tolerated by the horses

True

How do you anesthezise the pudendal nerve?

Insert 1.5" needle on right & left sides of penis

- Where penis curves around ischium

- Angle needle medially

-Aim for point on ischium slightly lateral to midline

-Deposit 5 mL at each site

What is Indicated for treatment of urolithiasis, soft tissue obstructions such as

neoplasia or strictures, trauma?

Perineal urethrotomy

What does the Perineal urethrotomy do?

Diverts urine flow in cases of distal urethral obstruction

T/F Perineal urethrotomy is used in male horses that cannot pass small stones

True

How is a Perineal urethrotomy done?

- Performed with the horse standing, sedated with epidural anesthesia

- Urinary catheter placed

- 6-8 cm midline incision created 4-6 cm ventral to anus

- Subcutaneous tissue, retractor penis muscles, bulbospongiosus muscle, corpus spongiosum penis divided

- Urethra identified and incised longitudinally

How long does it take a temporary urethrotomy to heal?

14-21 days

How do you preform a permanent urethrostomy?

muscles of the ventral penis are sutured to control hemorrhage, urethral mucosa sutured to skin with 2-0 or 3-0

T/F Avoid excess tension between the mucosa and skin closure on a urethrostomy

True