Urolithiasis in sheep, goats, cattle

What causes urolithiasis in sheep, goats, and cattle?

Urolithiasis (urinary calculi/uroliths) occurs when stones form and obstruct the urinary tract, causing trauma and blockage. Predilection sites depend on anatomical narrow points

What are key anatomic features contributing to obstructive urolithiasis in small ruminants?

• Fibroelastic penis

• Narrow urethra

• Urethral process in sheep/goats (very narrow)

• Sigmoid flexure creates angulation

• Urethral diverticulum in cattle

What species differences influence obstruction

• Sheep/goats have the narrow urethral process.

• Bovine penis shows differences when flaccid vs erect.

• Overall, small ruminants have narrower lumens → higher obstruction risk

What are the most common obstruction sites for uroliths?

• Urethral process (sheep & goats – most common)

• Sigmoid flexure

• Distal urethra

• Anywhere along the urethra if stone burden is heavy

What are the presurgical anesthesia and restraint considerations in cattle?

• Usually performed standing

• Caudal epidural commonly used

• Sedation only if absolutely necessary (risk of recumbency)

What anesthesia/restraint is used for sheep/goats?

• Dorsal recumbency

• Sedation or general anesthesia

• Positioning critical for access

Why are economics and clinical status important presurgical factors?

• Cost influences whether surgery is attempted (especially livestock)

• Clinical status matters:

  • Obstruction present

  • Urethral rupture

  • Bladder rupture (worse prognosis)

How does intended animal use affect surgical decisions?

• Feedlot steer: Just need urine outflow until slaughter

• Breeding bull: Must preserve penis function + remove obstruction

• Pet goat/sheep: Can consider temporary or permanent urine exit depending on recurrence or stone accessibility

What surgical options exist for obstructive urolithiasis?

• Urethral process amputation

• Perineal urethrotomy

• Perineal urethrostomy (temporary or permanent)

• Penile amputation

• Tube cystotomy

• +/- Bladder repair if ruptured

How is urethral process amputation performed?

• Restrain sheep/goat on rump

• Sedation + topical lidocaine

• Exteriorize penis (can be challenging)

• Cut urethral process with Mayo scissors

Why is urethral process amputation often done first?

• Most common obstruction site

• Quick and simple

• Check for full urine stream afterward (stone may remain at sigmoid flexure)

• Does not impact breeding ability in rams

What are the Perineal Urethrotomy/Urethrostomy surgical options?

• High vs low approach

• Temporary vs permanent urine exit

• Technique chosen based on obstruction location & animal use

What defines high vs low PU approach?

• High = at ischial arch

• Low = caudal to scrotum

When is the low approach used for Perineal Urethrotomy/Urethrostomy?

• To perform urethrotomy to remove calculi

• To perform urethrostomy + penile amputation for permanent urine exit

What are advantages of the low approach for Perineal Urethrotomy/Urethrostomy?

• Superficial penis → easier to exteriorize

• Provides access to sigmoid flexure

• Less skin irritation

• Can be repeated

What are disadvantages of the low approach for Perineal Urethrotomy/Urethrostomy?

• Awkward surgical position in standing cattle

• Stones may lie more proximally (need ultrasound/rads/contrast beforehand)

When is the high approach used for Perineal Urethrotomy/Urethrostomy?

For permanent urethrostomy via penile amputation

What are key advantages of the high approach for Perineal Urethrotomy/Urethrostomy?

• Position is proximal to almost all obstructions

• Sheep/goats often accumulate stones proximal to sigmoid flexure → accessible here

What are disadvantages of the high approach for Perineal Urethrotomy/Urethrostomy?

• Calculi often distal → may not be reachable

• Penis deep and difficult to exteriorize

• Higher risk of urine scalding (due to high urine outlet)

How do you choose between temporary and permanent PU?

Depends on surgical goals: preserve breeding function? Permanent urine exit? Stone removal? Animal value?

What are the purposes of temporary PU?

• Low approach over sigmoid flexure

• Provides temporary urine exit (heals by 2nd intention)

• Can remove calculi then suture closed

• Preserves penis function in breeding bull

What are disadvantages of temporary PU?

• Stricture formation, especially in sheep/goats

• Technically challenging

Why perform penile amputation during permanent PU?

• Easier exteriorization

• Easier urethral anchoring

• Distal penis is often nonfunctional due to obstruction or rupture

What approaches can be used for permanent PU?

• High or low approach (low preferred)

• Used for obstruction ± urethral rupture

• Provides permanent urine exit

What are the steps for permanent PU surgery?

• Dissect and exteriorize penis adequately

• Ligate dorsal penile vessels (proximal & distal “stick tie”)

• Amputate penis proximal to rupture/stone

• Spatulate urethra

• Suture urethral mucosa to skin edges for best results

What makes retrograde catheterization difficult in these species?

• Inability to exteriorize penis

• Sigmoid flexure

• Urethral diverticulum (especially in cattle)

When is tube cystotomy used?

• Sheep/goats with obstruction not relieved by urethral process amputation

• Especially pets or valuable breeding animals

What is done in tube cystotomy?

• Catheter placed via paramedian laparotomy & cystotomy

• Provides temporary urine drainage

• Allows prolonged medical dissolution of stones

How are bladder ruptures managed in livestock?

• Ideally surgically repaired → caudal paramedian inscision indwelling urinary catheter → aids healing then decompressed via catheter

• BUT rarely performed in cattle/goats/sheep due to economics

• More likely in pets or valuable breeders

What are the key postoperative treatments?

• Systemic antibiotics (if indicated)

• NSAIDs for analgesia/anti-inflammatory effect

• Tetanus prophylaxis

• Medical therapy to:

  1. Treat remaining calculi

  2. Prevent new calculi formation