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Dissolving Feline Struvite Stones

image of feline struvite bladder stoneStruvite is the most common feline stone analyzed by the Minnesota Urolith Center.  Diet has played an important role in struvite dissolution and prevention for over 35 years.  Dry and canned therapeutic foods are 100% effective in dissolving feline struvite uroliths in about 1 to 3 weeks.                                                          radiographs of a feline struvite dissolution case

The case of Lilly a 5-yr-old, female spayed DMH presenting with dysuria and hematuria.  The urinalysis did not reveal crystalluria. 
Radiography at Day 0 revealed one marginally radiopaque bladder stone consistent with a composition of Struvite. 
Repeat radiograph at Day 7 showed the stone had dissolved in 7 days while eating Feline c/d diet.  
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Protocol for Dissolving Feline Struvite Uroliths  (*ref)

  1. Start nutritional therapy. 
  2. Repeat radiographs in 2 to 3 weeks.
  3. If the stones are smaller, continue nutritional dissolution.  Repeat radiographs in 2-4 weeks.  If the stones have completely dissolved initiate Feline Struvite Prevention.

If stones are not smaller, re-evaluate diagnostic information to confirm stones are struvite (use CALCulator function on the MUC App).

Reasons why stones are not smaller:
  • Stones may not be struvite; consider other removal strategies. 
  • Stones are associated with a urease urinary tract infection.  Culture urine and administer antibiotics with diet to dissolve stones.
  • The cat is not eating the prescribed food.  Select a different flavor/formulation or consider a gradual food transition.  Remind owners of the rapid success with diet compliance.

Common Questions? (Click the + sign for explanation)

Is Urethral Obstruction likely when dissolving struvite stones in male cats?

Is Urethral Obstruction likely when dissolving struvite stones in male cats?

No.  The Truth:  In published studies on feline struvite dissolution, where approximately 1/3 of cats were male, no cat developed urethral obstruction.

Is Struvite crystalluria the primary method for predicting mineral composition?

Is Struvite crystalluria the primary method for predicting mineral composition?

No.  The Truth:  Crystalluria occurs in less than 10% of cats with struvite stones.  Radiographs in conjunction with the CALCulator function, on the MUC App, are the most accurate tools to predict mineral composition.

*Ref - Efficacy of two commercially available, low-magnesium, urine-acidifying dry foods for the dissolution of struvite uroliths in cats. Lulich JP, Kruger JM, Macleay JM, Merrils JM, Paetau-Robinson I, Albasan H, Osborne CA.  J Am Vet Med Assoc 2013, Oct 15:243(8); 1147-53.

Minnesota Urolith Center