Ch 112 - Penis and Prepuce

Question 1

Which part of the penis contains the urethra?

Answer 1

Corpus spongiosum

Question 2

Which part of the penis is most responsible for expansion during erection?

Answer 2

Bulbus glandis

Question 3

What is another name for the os penis?

Answer 3

Baculum

Question 4

List the extrinsic muscles of the penis

Answer 4

• Retractor penis
• Ischiocavernosus
• Bulbospongiosus
• Ischiourethralis

Question 5

What is the physiologic cause of erection?

Answer 5

• Parasympathetic stimulation causes profound increase of bloodflow through internal pudendal artery
• Engorgement of cavernous bodies due to expansion of arteries and contraction of veins
• Dorsal penile vein is compressed against ischial arch due to contraction os ischiocavernosus and bulbospongiosus muscles

Question 6

What occurs to the prepuce at puberty?

Answer 6

• Seperation of the prepuce from the penis and break down of the ventral frenulum under androgenis influence

Question 7

What is hypospadia?
What breed is overrepresented?
What are the various types?

Answer 7

• Failure of fusion of the urogenital folds and incomplete formation of the penile urethra
• Boston Terriers
• Glandular, penile, scrotal, perineal, analD

Question 8

What is the treatment for hypospadia?

Answer 8

Excision of preputial and penile remnants, bilater orchiectomy and enlargement/maintenance of the uerthral orifice in the scrotal or perineal region (urethrostomy)

Question 9

What is the most common consequence of an os penis deformity?
How is it treated?

Answer 9

Deformities usually form as an abnormal pronounced curvature and subsequently may not be able to retract the penis

Tx:
- Stranigtening may be possible with Fx
- Partial penile amputation

Question 10

List the Tx options for an os penis Fx

Answer 10

• Conservative
• U-cath
• Finger plate
• Partial penile amputation
• Scrotal urethrostomy if urethral obstruction

Question 11

What breeds are overrepresented for persistent penile frenulum?

Answer 11

• Cocker Spaniels
• Min Poodles
• Pekingese
• Mixed breeds

Question 12

List the most common types of penile tumours

Answer 12

• TVT
• Papilloma
• SCC
• mastocytoma
• HSA
• OSA of os penis

Question 13

List the Tx options for penile tumours

Answer 13

• Partial penile amputation
• Ablation of external genitalia and scrotal urethrosctomy
• More extensive amputation and perineal urethrostomy

TVT may respond to radiation, IV or intratumoral chemo and surgery

Question 14

What has been described with subtotal penile amputation to minimise skin irriation?

Answer 14

• Anastomosis of urethra to preputial mucosa

Question 15

List the surgical options for paraphimosis

Answer 15

• Temporary ot permanent surgical enlargement of the preputial orifice
• Phallopexy +/- preputial advancement
• Partial penile amputation

Prognosis is guarded as recurrence is common, especially with congenital causes. May require partial penile amputation

Question 16

What is phimosis?
What are potential causes?

Answer 16

Phimosis is the inability to protrude the penis.
Causes:
- Congenital - usually accompanied by distended prepuce and inability to urinate normally. Urine retention results in balanoposthitis
- Acquired - scarring from trauma, surgery, neoplasia

Question 17

What is the surgical treatment for phimosis?

Answer 17

Surgical enlargement of the preputial orifice
- V-shaped incision on the dorsal (dogs) or ventral (cats) surface of the prepuce
- Full thickness wedge resected and mucosa sutured to skin
- May need to be repeated when animal is fully grown

Question 18

List the most common preputial masses

Answer 18

• MCT
• SCC

Removal may require reconstruction with oral mucosa and skin flap in staged procedure, or partial penile amputation and urethrostomy

Question 19

What is the main surgical Tx of preputial hypoplasia?

Answer 19

• Preputial advancement

Prognosis guarded, often unsuccessful if more than 1.5cm of penis is exposed…
- May require phallopexy or partial penile amputation