Urinary Surgery in Ruminants

• Urinary surgery in ruminants focuses on reviewing prognosis factors and surgical procedures to treat obstructive urolithiasis.
• It also defines the indications, advantages, and disadvantages of each surgical procedure.

Peri-operative considerations

• With acute obstructions, patients are generally stable with few biochemical abnormalities.
• Chronic obstructions destabilize patients and can cause severe biochemical abnormalities as well as hypovolemic crises possibly leading to uroabdomen and hydronephrosis.

Urolithiasis diagnostic workup

• A physical exam, transabdominal ultrasound, and bloodwork are all important for the diagnosis of urolithiasis.

Transabdominal ultrasonography

• Ultrasonography helps visualize the distended urinary bladder.
• In obstructed goats the Mean bladder diameter in small goats (pygmy/Nigerian dwarf) is 7 cm.
• In obstructed goats the Mean bladder diameter in large goats (Nubia/Boer) is 9.5 cm.
• Ultrasonography assesses the abdomen for free fluid (uroabdomen) and can identify urethral or nephroliths as well as document perirenal edema.

Blood work abnormalities

• The severity of bloodwork abnormalities depends upon the duration of urinary obstruction.
• Possible bloodwork abnormalities include azotemia, hyponatremia, hypochloremia, hyphosphatemia, and hyperkalemia.

Pre-operative prognostic indicators associated with survival

• Being an intact male, less than 4 years old
• Having a short duration of clinical signs (≤ 24 h),
• Normal body condition score and demeanor
• Absence of uroabdomen or uroliths on urethral radiographs

Pre-operative prognostic indicators associated with non-survival

• Being castrated
• Body condition score of 4 or 5
• Presenting with severe lethargy, uroperitoneum, or elevated creatinine
• Having severe azotemia (BUN >216 mg/dL, creatinine >5.9 mg/dL), elevated packed cell volume, or hyperkalemia

Peri-operative considerations

• Animals with uroperitoneum who are hyponatremic, hypochloremic, and hyperkalemic, 0.9% NaCl IV fluids are most appropriate.
• Dehydration and severe electrolyte derangements should be corrected prior to general anesthesia.
• Urine should be removed slowly using a large-bore in-dwelling catheter with Concurrent administration of IV fluids.
• Antibiotic selection should be based upon surgical procedure, animals condition/value, anticipated time to slaughter and presence of urine leakage into tissues.
• Beta lactase (penicillin, cephalosporins) concentrate in urine.

Peri-operative complications

• Possible complications that owner should be warned about include cardiac or respiratory arrest during sedation, anesthesia or recumbency.
• Other ones are renal failure secondary to hydronephrosis, urinary tract infection (post-op), hemorrhage, dehiscence or stricture of urethra (post urethral surgeries).
• Potential re-obstruction can happen via movement of renal or urinary bladder uroliths into urethra

Urethral surgeries

• Urethral process amputation
• Penile amputation (penectomy)
• Perineal urethrostomy
• Urethrotomy
• Ischial urethrotomy with catheterization

Urethral process amputation

• This procedure involves exteriorizing the penis from the sheath and amputating the urethral process.
• Acepromazine (0.05 mg/kg - 0.1 mg/kg IM or IV) or Diazepam (0.1 mg/kg IV, slowly) can be used for sedation.
• 2% lidocaine (1 mL/15 lbs) total dose regardless of animal size should not exceed 15 mL used for lumbosacral epidural.
• This procedure rarely results in long-term cure and ~87% will reobstruct within 36 hrs

Penile amputation

• Summary: Penis is transected proximal to sigmoid flexure, proximal stump sutured to skin -Indication: Ruminants intended for slaughter. Allows temporary passage of urine.
  • Anesthesia: Caudal epidural (1 mL/200 lbs), might need additional local infusion of lidocaine
• Complications:
  • Trauma to penile stump by tail, urine scald, occlusion of urethral opening by blood, and urethral stricture

Perineal urethrostomy

• Perineal urethrostomy involves incising the urethra and suturing the edges of the urethral incision to the skin, creating a long-lasting urethral stoma.
• It is a "Longer” term fix than penile amputation but indication remains the same (i.e. for animals intended for slaughter).
• Urethrostomy should be performed just proximal to sigmoid flexure to minimize urine scald.
• If the urethra is ruptured, and the surgeon elects to ligate penile vasculature, the penile segment distal to the ligation should be removed.
• Complications are hemorrhage, extravasation of urine into subcutaneous tissues, dehiscence
• Other complication are Recurrent urethral obstruction (due to stricture or urolith)
• Traditional perineal urethrostomy should not be used in pet animals
• Stoma length in steer/bull is 10-15 cm.
• Stoma length in small ruminant is 3-6 cm.

Urethral surgery summary

• Urethral surgery procedures are suitable for field conditions and carry a reasonable prognosis for salvage of animals intended for slaughter.
• Urethral surgery alone is unlikely to be successful if urethral patency is required for several months (stricture formation).
• In bladder rupture, procedures do not allow direct visualization of the defect.
• Urethral surgery procedures are not suitable for animals intended for breeding or long-term survival (pets).

Bladder surgery

• Cystotomy with normal grade urethral lavage
• Tube cystotomy

Tube Cystostomy

• Laparotomy is performed. A Foley catheter is placed into the urinary bladder lumen and sutured to the skin allowing for continual drainage of the bladder.
• It Preserves breeding ability.
• Tube cystotomy can be performed in animals with a ruptured bladder as well as pet animals.
• General or heavy sedation plus a lumbosacral epidural (as described previously) is required for anesthesia.
• One must initiate Antibiotics (penicillin, ampicillin) prior to surgery and maintained at least 1 week after catheter removal.

Tube cystostomy overview

• Paramedian incision is made and used to enter the abdomen.
• Make a 1 cm stab incision into cranioventral aspect of bladder (if available lavage and suction of bladder to remove debris/stones).
• Perform a stab incision in abdominal wall 2 cm lateral to paramedian incision.
• A 20-26 French Foley catheter is passed through stab incision and paced into bladder, balloon inflated and drawn against the bladder wall.
• Secure the Foley with Purse-string suture of #0 Vicryl.
• Close the paramedian incision in routine fashion, Foley catheter sutured to the skin using finger trap suture.

Tube cystostomy considerations

• Small ruminants should have an Elizabethan collar fitted.
• Urine should be freely dripping from the Foley catheter.
• On the 7 day post operation, the Foley catheter should be occluded to determine if the urethra is patent.
• Unplug the Foley catheter and repeat the procedure daily until normal urine flow established if the patient vocalizes or is dysuric.
• The Foley catheter can be deflated and removed if an animal can urinate normally out of the urethra for 48 hrs.

Tube Cystostomy, Postoperative care

• IV or oral fluid therapy for azotemic animals is needed.
• Immediate post-op IV diuresis maintains the patency of the Foley catheter (flushes out blood clots etc.).
• Salt should be added back into the diet and appropriate dietary modifications are made when the animal's appetite returns.
• Non-steroidal anti-inflammatory drugs should be used judiciously in animals with urolithiasis due to their nephrotoxic potential.

Summary of traditional tube cystotomy

• Advantages: remove all calculi from bladder, preserve breeding ability, avoid urethral surgery, longer recurrence-free life after surgery, intact bladder not required, and remove remaining uroliths in the bladder.
• Disadvantages: high cost, difficult to perform in the field, and will not correct urethral stricture or rupture of the urethra.

Summary of modified tube cystotomy

• Advantages: Less expensive, can be performed in the field, short procedure time, preserve breeding ability, and avoid urethral surgery.
• Disadvantages: Does not remove remaining calculi from the bladder, restricted to smaller animals, urine contamination of the abdomen likely, will not correct urethral stricture or rupture of the urethra, and Intact bladder required.

Management of obstructive urolithiasis in cattle

• Feedlot steer or low value bull: Perineal urethrostomy
• Valuable bull or companion food animal: Ischial urethrostomy

Management of obstructive urolithiasis sheep or goats

• Feedlot lamb/goat low value buck/ram/wether: Urethral process amputation, Perineal urethrostomy
• Valuable buck/ram/wether Or pet: Urethral process amputation, Tube cystostomy, or Modified high perineal urethrostomy