Knowledge of the mineral composition of uroliths is important because contemporary methods of detection, treatment and prevention
of the underlying causes of urolithiasis are primarily related to knowledge of urolith composition. This discussion is based
on quantitative analysis of 47,036 canine uroliths submitted to the Minnesota Urolith Center in 2009.
Dr. Carl A. Osborne
In 1981, calcium oxalate was detected in only 5 percent of canine uroliths submitted to the Minnesota Urolith Center, whereas
struvite (magnesium ammonium phosphate) was detected in 78 percent. However, evaluation of the prevalence of different types
of minerals in canine uroliths during successive years revealed a gradual and consistent increase in occurrence of calcium
oxalate uroliths and a gradual and consistent decline in the occurrence of struvite uroliths (Figure 1, p. 14S). In fact,
by 2003 the prevalence of calcium oxalate (41 percent) was approximately equal to struvite (40 percent).
In 2004, calcium oxalate (41 percent) surpassed struvite (39 percent). In 2005, calcium oxalate was detected in 41 percent
of the urolith submissions, while struvite was detected in 38 percent. In 2009, the frequency of occurrence of calcium oxalate
(41 percent) and struvite (39 percent) remained about the same (Table 1; Figures 1, 2 & 3, p. 14S). Recall that the frequency
of feline calcium oxalate and struvite occurrence during the same period was similar. (For additional details related to feline
uroliths and feline urethral plugs, see "Epidemiology of feline uroliths and urethral plugs: Update 1981 to 2009" in the June
2010 issue of DVM Newsmagazine.) Why should we care?