Ch 112 Penis and prepuce Flashcards
Anatomy
Penis
- 3 divisions: the root, body, and distal portion
- The root is attached to the ischial tuberosity by the left and right crura. Each crus is composed of the proximal part of the corpus cavernosum and the ischiocavernosus muscle covering it
- corpora cavernosum and spongiosum constitute the main substance of the penile body.
- The distal portion, or glans, divided into the bulbus glandis, and the pars longa glandi
- corpora of the penis contain enlarged venous spaces
- os penis, or baculum, begins caudal to the bulbus glandis and extends almost to the tip of the glans.
Which part of the penis contains the urethra?
Corpus spongiosum
Which part of the penis is most responsible for expansion during erection?
Bulbus glandis
List the extrinsic muscles of the penis
Retractor penis
Ischiocavernosus
Bulbospongiosus
Ischiourethralis
The primary blood supply to the penis is from three branches of the artery of the penis, the continuation of the internal pudendal artery
What occurs to the prepuce at puberty?
Seperation of the prepuce from the penis and break down of the ventral frenulum under androgenis influence
What is hypospadia?
What breed is overrepresented?
What are the various types?
- Failure of fusion of the urogenital folds and incomplete formation of the penile urethra
- Boston Terriers
- Glandular, penile, scrotal, perineal, anal
What is the treatment for hypospadia?
- Preputial augmentation using a mucosal flap technique
severe cases
- Excision of preputial and penile remnants, bilater orchiectomy and enlargement/maintenance of the uerthral orifice in the scrotal or perineal region (urethrostomy)
What is the most common consequence of an os penis deformity?
How is it treated?
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
List the Tx options for an os penis Fx
Conservative
U-cath
Finger plate
Partial penile amputation
Scrotal urethrostomy if urethral obstruction
What breeds are overrepresented for persistent penile frenulum?
Cocker Spaniels
Min Poodles
Pekingese
Mixed breeds
frenulum normally ruptures by puberty under androgenic influences
List the most common types of penile tumours
transmissible venereal tumor
Papilloma
SCC
mastocytoma
HSA
OSA of os penis
List the Tx options for penile tumours
- Partial penile amputation
- Ablation of external genitalia and scrotal urethrosctomy
- More extensive amputation and perineal urethrostomy
Few long-term complications were observed after wound healing in 18 dogs undergoing penile amputation and scrotal urethrostomy
What has been described with subtotal penile amputation to minimise skin irriation?
Anastomosis of urethra to preputial mucosa
List the surgical options for paraphimosis
penis protrudes from the preputial sheath and cannot be replaced
- Temporary or 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
Lubricants, hyperosmolar solutions, and local cold to reduce the size
What is phimosis?
What are potential causes?
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
What is the surgical treatment for phimosis?
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
List the most common preputial masses.
How do you surgically treat these?
- MCT
- SCC
Removal may require reconstruction with oral mucosa and skin flap (caudal epigastric) in staged procedure, or partial penile amputation and urethrostomy
What is the main surgical Tx of preputial hypoplasia?
Preputial advancement
Prognosis guarded, often unsuccessful if more than 1.5cm of penis is exposed…
- May require phallopexy or partial penile amputation
penile amputation complication
- Urethral stricture may occur after partial penile amputation if healing is complicated
Primary preputial reconstruction following surgical
excision of cutaneous mast cell tumours without
penile amputation in eight dogs
R Hammerton, M Goodfellow 2024
NZVJ
Preputial advancement was
performed in 3/8 dogs to achieve adequate penile coverage. Histopathology confirmed all
CMCT were Kiupel low grade, Patnaik grade II with complete margins in 6/8 dogs
Two dogs encountered
minor complications (infection and a minor dehiscence) and one dog had a major
complication (infection with major dehiscence).
Preputial cutaneous mast cell tumours (CMCT) have
similar biological behaviour to those in other locations
of the body
historically involved wide excision
with 30-mm lateral surgical margins, penile amputation
and urinary diversion procedures such as scrotal
urethrostomy
Staged techniques have been described for preputial reconstruction
More recently, singlestaged,
preputial reconstruction techniques have
been described that have not required penile amputation
and urethrostomy: a combined caudal-superficialepigastric
axial pattern flap and full-thickness buccal
mucosa graft (Massari et al. 2018
partial penile amputation following prepucectomy
and primary preputial reconstruction
The indications, complications and outcomes of dogs undergoing partial penile amputation: 10 cases (2014-2021)
K. Ritson 2023
Indications for surgery were treatment of preputial MCT (n=5), penile SCC (n=1), idiopathic paraphimosis (n=3) and chronic urethritis (n=1)
Two of the three dogs treated for paraphimosis had major postoperative complications requiring further resection of the tip of the penis at 2 weeks and 24 months. Four dogs had minor complications
- scar tissue formation at the surgical site resulting in urethral stricture
- haemorrhage, with dysuria 4 days after surgery requiring further hospitalisation and urinary catheter placement for 5 days
good to excellent in nine of nine dogs
facilitate the maintenance of micturition via the penis.
urethrostomy following total penile amputation have been associated with postoperative haemorrhage, wound dehiscence (Burrow et al. 2014), urine scald of the inguinal region, recurrent urinary tract infections (Newton & Smeak 1996), skin irritation, and odour, requiring regular management
urethral stricture, haemorrhage from the urethrostomy site and voiding of urine into the prepuce are potential complications of PPA
Cranial translation of the elevated prepuce in dogs before and after two modifications: A cadaveric study
Yiapanis 2021
modification to preputial advancement to improve cranial translation, cadaveric
- elevation of prepuce from ventral body wall, release of skin caudal to prepuce and release
of attachments of lamina interna to penis
→ improved cranial translation 15mm, 25mm and 37mm with each step
- large range in resulting translation
Combined caudal-superficial-epigastric axial pattern flap and full-thickness buccal mucosa graft for single-stage preputial reconstruction in six dogs
F. Massari 2018
Outcome was assessed by routine clinical examinations for 6 months postoperatively, and through telephone follow-up thereafter.
R esults: Six dogs were included. The caudal superficial epigastric axial pattern flap healed without complications in all dogs, while the full-thickness oral mucosal/submucosal graft failed in one dog.
Three (50%) dogs developed paraphimosis at 30, 80 and 90 days, respectively, and required further surgery. Long-term results were good in all dogs.
Endoscopic evaluation of the preputial mucosa shows complete
mucosal covering of the axial pattern flap 16 weeks postoperatively
The high complication rate encountered
in this case series raises the question whether a single stage reconstruction
of the prepuce may actually be superior to previously
reported techniques.
However, our clinical experience
with this small series of dogs suggests that lack of mucosal
lining may result in a more pronounced scar contraction and
consequent paraphimosis. To prevent this complication, it may
be advisable to create a larger preputial orifice (30 to 40% more
than a normal preputial opening),
