The role of diet control
The increase in the frequency of feline struvite over calcium oxalate from 2003 to 2011 may be associated with a decreased
use of diets designed to dissolve sterile feline struvite uroliths as a consequence of the significant increase in calcium
oxalate uroliths in the 1980s and 1990s.
The significance of struvite as the predominant mineral type emphasizes the importance of considering a struvitolytic diet
to manage cats at risk for struvite urolithiasis. Currently, therapeutic diets are available that promote struvite urolith
dissolution in a short period. In a double-blind study, a therapeutic diet (Prescription Diet c/d Multicare Feline—Hill's
Pet Nutrition) performed as expected in the dissolution of sterile struvite uroliths.1 It's likely that some, if not most, of the 5,885 feline struvite uroliths submitted to the Minnesota Urolith Center in 2011
could have been readily dissolved in one to four weeks by feeding diets designed to promote formation of urine that is undersaturated
However, not all uroliths can be dissolved with dietary manipulation. Those uroliths that have not shown evidence of dissolution
in three to four weeks (provided the owner is compliant with feeding instructions) should be removed and sent to a reputable
laboratory for evaluation of mineral composition.
We are still searching for a diet that is safe and consistently effective in minimizing calcium oxalate uroliths.
Editor's note: The Minnesota Urolith Center—with the support of an educational gift from Hill's Pet Nutrition as well as contributions from
veterinarians and pet owners—provides quantitative urolith analysis at no charge. Online submission, email notification and
electronic retrieval of results are available. With access to our database of 730,000 samples, the veterinary community is
offered the latest information on urolith trends, treatment and prevention suggestions. For details, visit
1. Lulich JP, et al. Struvite urolith dissolution in cats: a double blind randomized clinical trial of 2 foods, in Proceedings. Am Coll Vet Intern Med Forum, June 2011.
Dr. Osborne is director and a professor at the College of Veterinary Medicine at the University of Minnesota.
Dr. Lulich is the co-director of The Minnesota Urolith Center and professor of Veterinary Internal Medicine at the University of Minnesota.
For a complete list of articles by Dr. Osborne, visit