Implications for practice
The significance of infection-induced struvite as the predominant mineral type in dogs and sterile struvite as the predominate
mineral type in cats—and the fact that the etiology of sterile struvite and infection-induced struvite is different—is of
great importance when formulating therapeutic plans. An appropriate antimicrobial agent in addition to an appropriate diet
(e.g., Prescription Diet s/d Canine canned—Hill's Pet Nutrition) is required to consistently induce dissolution of infection-induced
uroliths, while the prevention of urinary tract infections is essential to minimize recurrence of infection-induced uroliths.
A special diet is not necessary. Consumption of an appropriate diet (e.g., Prescription Diet c/d Multicare—Hill's Pet Nutrition)
is usually effective in dissolving and minimizing recurrence of sterile struvite uroliths.
Figure 3: Mineral composition of 52,562 canine uroliths, 2010. Note: CaOx = calcium oxalate; MAP = struvite; CaPO4 = calcium
phosphate; Cmpd = compound.
A surprising trend
During the past 30 years, the number of canine urolith submissions has exceeded the number of feline urolith submissions by
a ratio of about 4 to 5:1. This trend is surprising given that the number of cats living with families in the United States
is greater than the number of dogs living with families. For example, in 2010, we received 52,562 canine uroliths and 12,312
feline uroliths. This results in a ratio of 4.3 canine uroliths for every feline urolith that we received. We welcome the
ideas of readers to explain this seemingly paradoxical trend.
Figure 4: CaOx = calcium oxalate; MAP = struvite.
Editor's note: With the support of an educational gift from Hill's Pet Nutrition, as well as contributions from veterinarians and pet owners
worldwide, the Minnesota Urolith Center is providing quantitative urolith analysis at no charge. Online submission, e-mail
notification and electronic retrieval of results are available. With a database of more than 670,000 samples, the veterinary
community is offered the latest information on urolith trends, treatment and prevention suggestions. For details, visit
Dr. Osborne is professor of medicine at the College of Veterinary Internal 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.
1. Osborne CA, Lulich JP. Feline urolith epidemiology: 1981 to 2010. DVM Newsmagazine June 2011; 50-53.
For a complete list of articles by Dr. Osborne, visit