Chapter 67 - Urethra Flashcards
What is the length range of the male horse’s urethra
male horse’s urethra is approximately 75 to 90 cm long
how does the intrapelvic portion widen in diameter?
The intrapelvic portion widens in an elliptical pattern to a diameter of 5 cm (2 in) across and 2 to 3 cm (1–1.5 in) from dorsal to ventral.
What structure is found a few centimeters caudal to the male horse’s urethral orifice, and what is its significance?
The** colliculus seminalis i**s found a few cms caudal to the urethral orifice. It is the site of the paired ejaculatory ducts, which are the common openings of the ductus deferens and ducts of the seminal vesicles.
Where are the openings of the prostatic ducts located in the male horse’s urethra? and how are they arranged?
The openings of the prostatic ducts are arranged as two groups of small papillae on either side of the colliculus seminalis.
Where do the bulbourethral glands open in the male horse’s urethra, and how are they positioned in relation to the colliculus seminalis?
The bulbourethral glands open in paired dorsal rows of 6 to 8 ducts each, positioned 2 to 3 cm farther caudad from the colliculus seminalis.
What is the terminal structure of the male horse’s urethra, and what protrudes under the tip of the glans penis?
The urethra terminates at the** glans penis**, where a urethral process protrudes 1 to 2 cm under the tip of the glans.
What is the composition of the penis in terms of vascular, erectile bodies, and what is the role of the CCP and CSP?
The penis comprises two vascular, erectile bodies:
- a larger corpus cavernosum penis (CCP)
- smaller corpus spongiosum penis (CSP).
The CCP forms most of the dorsal aspect, while the CSP forms a vascular tube surrounding the urethra along the ventral aspect.
What is the role of the bulbospongiosus muscle?
bulbospongiosus muscle is a continuation of the urethralis muscle It surrounds the** CSP around the urethra and extends from the ischial arch to the glans penis.
It acts to empty the CSP of blood **after ejaculation or urination.
What muscle covers the intrapelvic urethra in the male horse, and what is its significance in ejaculation?
The urethralis muscle covers the intrapelvic urethra and bulbourethral glands. Its forcible contraction plays an important role in ejaculation.
What is the function of the urethral process in the male horse’s penis
urethral process protrudes under the tip of the glans penis
Above urethral process there is the urethral sinus, a bilobed, recessed area where the “bean” of smegma accumulates.
What is the length of the female horse’s urethra, and where is its external opening located?
The female horse’s urethra is about 5 cm (2 in) long, and its external opening lies at the anterior end of the vestibule.
What are the disorders of the urethra that require surgery?
Congenital:
1) rectourethral fistula
2) rectovaginal fistula
Acquired
1) urolithiasis
2) soft tissue obstructions
3) hematomas
4) lacerations
A positive contrast urethrogram in a 3-day-old burro thatpresented with atresia ani and intermittent passage of fecal material fromthe urethra. A catheter was passed via the urethra and contrast agentwas injected, resulting in accumulation of a large amount of contrastagent in the rectum and a lesser amount in the intrapelvic portion of theurethra. A small amount of contrast agent can be seen in the urethrorectalfistula (arrow).
What signs may support the presence of rectourethral or rectovaginal fistulas in affected foals?
Passage of fecal material from the vulva or penis is a sign supporting the presence of rectourethral or rectovaginal fistulas in affected foals.
What diagnostic procedures are used to confirm rectovaginal fistulas in fillies and rectourethral fistulas in colts?
Digital palpation of the dorsal vestibule and vagina may detect rectovaginal fistulas in fillies. In colts, a definitive diagnosis usually requires contrast radiographic procedures like a **barium enema **or a retrograde urethrogram.
Is there evidence of hereditary factors associated with rectourethral and rectovaginal fistulas in horses?
Yes
What are the clinical signs of obstructive urethrolithiasis in male horses?
Obstructive urethrolithiasis in male horses can present with bladder distention, frequent posturing to urinate, renal colic, and a persistently dropped penis that may drip urine.
How can obstruction be confirmed in horses with obstructive urethrolithiasis?
Detection of a markedly **distended urethra **below the anus
**+ large, turgid bladder **on rectal palpation can confirm obstruction in horses with obstructive urethrolithiasis.
Emergency condition!!
What complications may arise in horses with obstructive urethrolithiasis that has persisted for more than 1 to 2 days?
Bladder leakage or **rupture **may occur, leading to abdominal distention from uroabdomen in horses with obstructive urethrolithiasis persisting for more than 1 to 2 days.
How is obstructive urethrolithiasis typically treated to prevent bladder rupture?
perineal urethrotomy (PU) into the distended urethra to prevent bladder rupture.
What is the composition of urethroliths in horses, and what are their characteristic features?
Urethroliths are 1rily composed of calcium carbonate crystals - spiculated - allowing them to become embedded in the surrounding urethral mucosa.
What are the alternative methods if a urethrolith cannot be dislodged by hydropulsion or gentle prodding?
snaring the stone using a device passed through the biopsy channel of an endoscope, or endoscopically guided electrohydraulic or laser lithotripsy.
What novel approach involves shock wave therapy for urethrolith fragmentation in equids?
Radial extracorporeal shock wave therapy (RSWT), using a device commonly used for therapy of musculoskeletal problems, was reported to successfully fragment obstructive urethroliths in three equids.
How is second-intention healing of PU incisions related to urethrolith removal in horses?
results in dilation of the urethra** above the ischial arch, and urethral strictures** are more likely a consequence of damage and associated inflammation.
What complications may arise if an indwelling urethral catheter is used for an extended period after urethrolith removal?
increase the risk of ascending urinary tract infection.
A cross section of the equine penis at the level of theischial arch showing two separate vascular structures: A, Corpus cavernosumpenis; B, urethral lumen; C, corpus spongiosum penis; D, bulbospongiosismuscle.
Figure 67-4. Gross pathology photographs of the urinary tract from a 17-year-old Arabian gelding that suffered four bouts of obstructive urethrolithiasis over a 10-year period. The right kidney and ureter
were enlarged (A) and the kidney parenchyma had been replaced by an abscess containing multiple nephroliths (B).
Figure 67-3. Endoscopic images of the urethra revealing distention at the level of the ischial arch
(A) and a urethral stricture at the site of a previous obstructing urethrolith (B). Both images were recorded approximately 1 year following the initial examination.
Figure 67-5. Photographs of the front view (A) and hind view (B) of the prepuce and ventral abdomen of a horse with marked tissue inflammation and necrosis several days following urethral disruption and accumulation of urine in tissues of the perineum, prepuce, and ventral abdomen
Figure 67-6. A cross section of the equine penis at the level of the ischial arch showing two separate vascular structures: A, Corpus cavernosum penis; B, urethral lumen; C, corpus spongiosum penis; D, bulbospongiosis muscle.
Figure 67-7. Four endoscopic images showing the variable appearance of urethral rents (arrows) causing hematuria at the end of urination in geldings or hemospermia in stallions. A consistent finding is that urethral rents are located along the concave (or caudal) aspect of the urethra at the level of the ischial arch.
Figure 67-8. The urethral incision is performed immediately dorsal to the ischium to decrease the likelihood of postoperative urine scalding in a horse with a perineal urethrotomy. Preoperative placement of a stallion urinary catheter facilitates intraoperative identification and exposure of the urethra.
Figure 67-9. Perineal urethrotomy for temporary urinary diversion will heal by secondary intention with minimal complications.
Figure 67-10. (A) Perineal urethrostomy for chronic urinary diversion after partial phallectomy by EN BLOC resection in a gelding with severe preputial and penile squamous cell carcinoma. (B) Accurate apposition of mucosal and cutaneous layers is essential to minimize postoperative complications.
Asymmetry of the perineum in two geldings with proximal urethral rents causing hematuriaimmediately after urination. (A) Note widening of the perineum
