Equine Urinary Tract Sx

Question 1

General Considerations

Answer 1

Presenting complaints: low-grade abdominal pain, weight loss, stranguria, dysuria, hematuria, oliguria, incontinence
Observation of micturition is particularly important
Evaluate for systemic abnormalities: toxemia, electrolyte or acid-base derangements
- Especially important for cases of uroperitoneum
Rectal exam: pelvic urethra, bladder, left kidney
Useful imaging modalities: ultrasound, endoscopy

Question 2

More General Considerations

Answer 2

You may be working in a (deep) hole!
- Long surgical instruments should be available
- Consider laparoscopy as an alternative
Choose suture material appropriate to tissue type
- Never use non-absorbable suture in the urinary tract (ideally, don’t expose suture to urine at all)
The kidney is important in pharmacology!
- Renal effects of antimicrobials (e.g. aminoglycosides), anti-inflammatories (e.g. NSAlDs)
- Sensitive to hypoperfusion resulting from hypotension — concern under general
anesthesia

Question 3

Common conditions

Answer 3

Adults 
- Urolithiasis 
 . Bladder 
 . Urethra 
- Urethral obstruction (non-calculus) 
- Hematuria/hemospermia 
Foals 
- Uroperitoneum 
 . Ruptured bladder 
 . Ruptured urachus 
- Patent urachus

Question 4

Less Common Conditions

Answer 4

Adults 
- Urolithiasis 
 . Kidney 
 . Ureter 
- Bladder eversion 
- Urethrorrhexis 
- Neoplasia/dysplasia 
- Pyelonephritis 
Foals 
- Ectopic ureter 
- Ureterorrhexis

Question 5

Urolithiasis of adult horses

Answer 5

Bladder most common calculus location (69%)
- More common in males, > 10 yrs
- Urethral obstruction most common at junction of pelvic and extrapelvic urethra
- Calcium carbonate
. May be white or yellow, speculated or smooth
- Clinical signs vary by location
. Kidney/ureter: weight loss, anorexia, colic
. Bladder/urethra: hematuria, stranguria, dysuria
- Posturing to urinate frequently but not actually doing so
- Mild colic due to bladder distention (urethral obstruction)

Question 6

Dx of Urolithiasis in adults

Answer 6

Rectal exam
- Single large bladder stones easily palpable
Ultrasound
- Highly echogenic structure that casts an
acoustic shadow
Endoscopy
- Direct visualization of bladder/urethral stones
- Evaluation of urine output from each ureter in the trigone region
Bloodwork
- May not see changes unless advanced/chronic renal disease

Question 7

Tx of Urolithiasis in adults

Answer 7

Kidney/Ureter 
- Nephrectomy 
- Nephrotomy 
- Ureterotomy 
Bladder/Urethra 
- Lithotripsy, mechanical crushing 
- Cystotomy 
- Perineal urethrotomy (males) 
- Distal urethrotomy (males) 
- Urethral sphincterotomy (females) 

Avoid the use of xylazine and other alpha-2 agonists in patients with urinary obstructions due to diuretic effects! ***

Question 8

Nephrectomy in adults

Answer 8

Treatment of choice for unilateral hydronephrosis, abscess, neoplasia, ureteropelvic polyp, ectopic ureter, severe unilateral ureterolithiasis/nephrolithiasis
Transcostal/flank approach (lateral recumbency)
Midline celiotomy approach
Laparoscopic-assisted flank approach (standing)
Good long-term outcome has been reported

Question 9

Nephrotomy/Ureterotomy in adults

Answer 9

Nephrotomy — same surgical approach as nephrectomy, not less complicated
- Capsular sutures or parenchymal mattress sutures recommended
Ureterotomy indicated for obstructive urolithiasis or ureterorrhexis (rare)
- If obstruction can be identified and exposed (limited access to posterior ureter), incise proximal to obstruction and evacuate contents
- Silastic tubing in ureter to act as a stent over which repair can be performed
- If cannot remove surgically, can try to use a grasping basket for closed dislodgement
Good short-term outcome

Question 10

Cystotomy in adults

Answer 10

Indicated for removal of large bladder stones
Caudoventral midline approach
Parainguinal approach: 12-14cm skin incision
starting 2cm cranial to left external inguinal ring and
continuing caudomedially toward midline
Laparotomy assisted parainguinal approach — hand
in ventral midline incision helps guide bladder
toward inguinal incision where it is exteriorized and
the stone removed
Laparoscopy assisted para-inguinal approach

Question 11

Perineal Urethrotomy in adults

Answer 11

Most often a temporary diversion for
distal urethral obstruction, or to access stones in bladder
- Will heal in —2-3 weeks
- Can make permanent urethrostomy
Size limitation of stones that can be removed

Question 12

Perineal Urethrotomy Procedure in adults

Answer 12

Standing sedation, epidural, +/- local block;
ideally catheter placed to aid identification
6-8cm midline incision extending from 10-
15cm ventral to anus to the ischial arch
- Divide bulbospongeosus mm. and corpus spongeosum — retract to expose urethra
- Longitudinal incision into urethra
Potential complications: hemorrhage,
scalding, bladder rupture, urethral stricture
Uroliths can recur
- Reduced risk if post-op cystoscopy/lavage

Question 13

Distal Urethrotomy in adults

Answer 13

Scrotal or pre-scrotal approach for uroliths that are too proximal to be removed with endoscopic-guided grasping forceps
- Dorsal recumbency
Similar approach to PU, except incision made over or slightly proximal to obstruction
Important to accurately reconstruct the corpus spongiosum and bulbospongeosis mm. to reduce risk of urine leakage

Question 14

Aftercare - Urethral Surgery in adults

Answer 14

Monitor for normal urination
Antibiotics and anti-inflammatories as appropriate for the case
Chronic catheter placement debated
- May increase risk of urethral stricture
- Recommendation is to remove as soon as possible (48-96hr)
Protect the skin against urine scald**

Question 15

Obstructive Soft Tissue Lesions of the Urethra in adults

Answer 15

Neoplasia 
- Squamous Cell Carcinoma (most common) 
- Melanoma 
- Sarcoid 
Scar tissue 
Hematoma 
Parasitic granuloma 
Usually fairly distal 
- Typically treat by surgical excision/amputation

Question 16

Hematuria/Hemospermia in adults

Answer 16

Urethral defects communicating with 
corpus spongeosum — etiology still 
debated 
Temporary perineal urethrotomy to 
relieve pressure during micturition — 
do not have to enter lumen 
May perform urethroplasty if needed 
- Repair as for any hollow organ

Question 17

Urethrorrhexis in adults

Answer 17

Kicks or other external trauma, most often at level of
ischial arch
Pronounced soft tissue inflammation secondary to
urine extravasation
Most often managed with placement of urinary
catheter for 5-7d; don’t need to repair unless
completely transected
- End-to-end anastomosis if circumferential

Question 18

Other Conditions in Adults

Answer 18

Renal neoplasia and dysplasia
- Rare
- Renal adenoma, primary renal cell carcinoma, undifferentiated renal sarcoma, metastatic tumors
- Dysplasia may be secondary to obstruction from benign polyps
Pyelonephritis
- Uncommon, not treatable surgically if disseminated bilateral disease
Diagnostic tools: ultrasound, renal biopsy, bloodwork

Question 19

Renal Biopsy in adults

Answer 19

Percutaneously (flank) - with or without ultrasound or laparoscopic guidance
- Left kidney easier/safer if done blindly
- Guidance allows selection of biopsied region and avoidance of large vessels
Complications: perirenal hemorrhage/hematoma, usually self-limiting
Multicenter retrospective
- 11.3% complication rate; 3% required treatment; 0.7% fatal
- Specimens sufficient for histopathologic diagnosis in 94% of cases, but only agreed with necropsy diagnosis in 72% of cases

Question 20

Other, other conditions in adults

Answer 20

Bladder eversion
- Secondary to third-degree perineal laceration
- Manual reduction followed by foley placement and pursestring
- Partial cystectomy if devitalized
Bladder neoplasia
- Rare — SCC most common

Question 21

Uroperitoneum in foals

Answer 21

Uremia, severe electrolyte and acid- base abnormalities
- Serum-to-peritoneum creatinine ratios; diagnostic if 1:2
In foals, most often ruptures along dorsal or dorsocranial margin
- present at 1-5 days of age
Medically stabilize BEFORE surgery

Medical, not Sx emergency. If not stabilized before Sx, will die

Question 22

Cystorrhaphy in foals

Answer 22

Indicated for bladder rupture
Caudovental midline incision — skin incision abaxial to prepuce/penis in males (retract laterally)
Mobilize umbilicus and urachal remnant — traction to expose bladder
If rupture site not obvious, retrograde inflation of bladder
- Urachal rupture can be sequela of urachal infection (especially septicemic foals)

Question 23

Cystorrhaphy in foals

Answer 23

Monofilament stay sutures, 
debride edges of rupture 
2 layer continuous closure — 
appositional, then inverting 
Check suture line for leaks, 
copious lavage

Question 24

Cystorrhaphy in adults

Answer 24

Bladder rupture occurs occasionally in
adults
Standing repair in postpartum mares
- Evert bladder via vaginal approach (5-
10cm caudal to cervix) or urethrotomy/sphincterotomy (place hand through incision)

Question 25

Patent Urachus in foals

Answer 25

Typically related to omphalophlebitis —
check for systemic/distal infection
Surgical resection if severe infection, or medical management has not resolved in 5-7 days

Question 26

Cystoplasty in foals

Answer 26

Indicated for patent urachus
Caudoventral midline incision, elliptical
incision around umbilicus
- Umbilicus/urachus dissected free
Falciform ligament and umbilical v. ligated as far forward as possible; umbilical aa. ligated at level of urachal resection

Question 27

Cystoplasty in foals continued

Answer 27

Occluding forceps across the apex of bladder, stay
sutures (reduce contamination), resect
2 layer continuous closure
- Appositional, then inverting

Question 28

Outcomes in foals

Answer 28

Bladder rupture:
- Of 18 foals, 8 bladder, 7 urachal tears, 3 could not be identified
- 9/18 alive at 6mo; 7/9 euth due to fungal or bacterial infx
Patent urachus (omphalophlebitis):
- Of 18 foals, 9 survived
- 2/7 with joint involvement survived
Bottom line: concurrent disease is a major issue in foals

Question 29

Uretororrhexis in foals

Answer 29

Congenital, fillies more likely to be affected
Presenting clinical complaint uroperitoneum
- Site of leak identified by excretory ureterography, ultrasound, or surgical explore

Question 30

Ectopic Ureter in foals

Answer 30

Faulty differentiation of metanephric duct; no sex or breed predilection
Anomalous ureters insert distal to trigone -> incontinence
Evaluate for concurrent hydronephrosis and hydroureter
Better success if intervention is early

Question 31

Neoureterostomy in foals

Answer 31

Treatment for ectopic ureters
- Caudoventral midline incision, Sl retracted cranially
- End-to-side or side-to-side anastomosis if close to dorsal bladder
- Intravesicular anastomosis with tunneling if not close to bladder (to get functional equivalent to distal ureteral valve, reduce risk of vesiculoureteral reflux)
Limited reports — nephrectomy more common if unilateral

Question 32

Muthafukkin Summary

Answer 32

Obstructive lesions of the urinary tract most common in adults
- Bladder, urethra most common; males more likely to be affected
- Diagnosis via palpation, ultrasound, endoscopy
- Surgical removal nearly always indicated
. Nephrectomy, cystotomy, perineal urethrotomy, distal urethrotomy
Rupture/infection of the bladder/urachus most common in foals
- A medical emergency, not a surgical emergency
- Definitive surgical repair often delayed for 5-7 days
. Cystorrhaphy, cystoplasty