B. Dietary intervention
- the main diet used for dissolution of struvite uroliths in dogs is Hill's Prescription Diet s/d, although Waltham S/O Lower
Urinary Tract Support can also be use.
- some very important points to keep in mind about Hill's Prescription Diet s/d are:
o /d is very high in fat, and therefore it is contraindicated in any dogs with a history of pancreatitis or hyperlipidemia
o although the development of pancreatitis in dogs consuming s/d is relatively uncommon, it can nonetheless occur.
o dogs should be gradually transitioned from their current diet to s/d over the course of 7 to 10 days.
o if at any time the dog starts to vomit, discontinue s/d and monitor for pancreatitis
- s/d is very low in protein, and is not meant to be used long-term (>6 months)
- it is contraindicated to supplement dogs with methionine that are consuming s/d.
C. Recheck protocol
- the larger the stone, the longer it will take to dissolve
- many dogs become asymptomatic long before all of their stones are dissolved.
- recommend monthly rechecks and obtain at a minimum a lateral abdominal radiograph and a urine culture
- once stones no longer visible on radiographs, continue dissolution protocol (antibiotics and s/d) for an additional "insurance"
month to ensure microscopic crystalline material not visible on radiographs dissolve.
3. Prevention of Recurrence
- The single most important thing to do to prevent recurrence of infection-induced struvite urolithiasis is to prevent UTI and
retreat promptly if it recurs.
- if a dog had infection-induced struvite urolithiasis, once stones are successfully dissolved, I usually do not recommend
feeding an acidifying therapeutic diet, but rather suggest they feed whatever diet they were feeding prior to developing stones
or some other maintenance diet.
- Many of the breeds that we see with increased risk for developing struvite uroliths are also breeds with increased risk for
developing calcium oxalate uroliths.
- If a dog had rare sterile struvite stones, then dietary management may be necessary to prevent recurrence.
Calcium Oxalate Urolithiasis
1. Background Information
- the majority of dogs diagnosed with calcium oxalate urolithiasis are not hypercalcemic
- proposed reasons for why some normocalcemic dogs develop calcium oxalate uroliths are:
o excessive GI absorption of calcium (intestinal hyperabsorption of calcium)
o excessive renal loss of calcium
o defective nephrocalcin, a glycoprotein that inhibits calcium oxalate crystal growth
2. Medical Dissolution Protocol
- currently, calcium oxalate uroliths in dog can not be medically dissolved.
- therapeutic options available
o if stones are detected when they are small enough, they may be able to be removed via a urinary catheter or by voiding urohydropropulsion (Lulich JP. VCNA Small Anim Prac 29:283-292, 1999)
o if stones are too large to be removed non-surgically, and the dog is symptomatic, it may be necessary to initially remove
all the stones surgically, and then take appropriate dietary and monitoring steps to detect recurrence of stones when they
are small enough to remove non-surgically (i.e. via urinary catheter or voiding urohydropropulsion).
A. Recurrence of calcium oxalate uroliths in dogs is common. In 1992, Lulich published an abstract (JVIM) that revealed that
recurrence rates of calcium oxalate uroliths in dogs 12 months after surgery was 36%, after 24 months was 42%; and after 36
months was 48%.