Ruminant urolithiasis

Treatment

Enable urination by amputation of the vermiform appendage, tube cystotomy or other procedure OR relieve the bladder via cystocentesis. The most common procedures are amputation of the vermiform appendage, penile amputation and tube cystotomy.

Amputation of the vermiform appendage

Amputation of the vermiform appendage can help temporarily. The offending stone is removed but there are often dozens of stones in the bladder and urethra. It is just a matter of hours before more come down the urethra and become lodged. This procedure may allow you to schedule the surgery in daylight hours rather than at 2am.

Perineal urethrostomy

Perineal urethrostomy is not a great choice in ruminants due to their propensity to stricture. It is acceptable in feedlot steers as their lifespan is limited. However, penile amputation is easier.

Penile amputation

Tube cystotomy

Tube cystotomy is recommended for most pet goats and any ruminant males used for breeding. Surgery is performed under general anesthesia. Cystotomy is performed, as many stones are removed as possible with gentle flushing and a tube placed in the bladder that exits the body wall. The tube allows urine to flow freely while the urethra is still obstructed. The remaining urethral stones will usually pass on their own after the urethra stops pulsating closed.

Antibiotic coverage (usually ampicillin) is maintained while the tube is in place due to the risk of ascending infection

The tube is removed once the goat can urinate on his own through the penis. The goats will usually start urinating normally once the urethra is cleared, even with the tube still in place. Generally we leave the tube in for at least 8 days to create an adhesion to the body wall (this number is pulled out of thin air, as far as I can tell)

Modified tube cystotomy

Bladder marsupialization

Laser lithotripsy

Stone passage (removal, dissolution, relaxation)

Retrograde or anterograde flushing of the urethra tends to cause urethral rupture.

Saline flushes may help dissolve stones due to the pH of the saline. Saline can be flushed into the bladder via the tube cystotomy tube.

Minimize the risk of recurrence

Once a stone former, always a stone former. Dietary adjustments are needed:

• • avoid alfalfa hay, oreo cookies, dog chow
  • encourage dilute urine by salting the food. Owners can gradually increase salt levels to 3-5% of the dry matter intake or about 60-100 grams of salt for a 100kg animal
  • ensure a reliable source of clean water
  • soychlor or pasturechlor is the most effective dietary adjustment we have currently for herd level management

Many people incorrectly believe ammonium chloride in the feed is effective. It works but goats don’t like it. For effective use, it needs to be given orally as a medication. This means it works better in individual animal management rather than herd management. Table sugar helps mask the flavor.  Ammonium chloride should also be given in a pulsatile fashion – it stops working if given continuously;  titrate the dose to a level that acidifies the urine (pH <6.5) in the affected animal, then treat three days on, four days off. If owners can check urine pH, this may be a useful feed additive for phosphatic urolithiasis; check pH 5-7 hours after giving the acidifier. Oral D, L-Methionine at a dosage of 200 mg/kg can also decrease pH.

Manage related complications and pain

Complications include uremia, urinary tract infections, ruptured bladders, and/or ruptured urethras.

Analgesics are needed, especially for goats. Goats are pretty sensitive to pain and will tend to be in rough shape for a day or two post-operatively. Consider phenazopyridine (relieves bladder irritation), narcotics and NSAIDs. Uremic animals are not edible. All uremia needs to resolve before an animal is shipped for meat. This can take several weeks.