World-wide the relative frequency of calcium oxalate increased from 2.5% in 1981 to 60% in 1994, stabilized ~60% between 1994 and 2002, and declined to ~50% since 2002. The causes for these changes are unknown. However, changes in nutritional practices are an important consideration.

We investigated whether a similar development occurred in three European regions. All uroliths were analysed by Minnesota Urolith Center.

In Denmark and Benelux, a similar increase in relative frequency of calcium oxalate urolithiasis occurred with a delay of about five years, and it has stabilized at ~65% since 1997/1998. In Spain, the relative frequency of calcium oxalate has remained stable at ~45% from 2001, i.e., struvite uroliths have consistently been the most frequently submitted stone type.

We hypothesize that the decrease in relative frequency of struvite uroliths in Denmark and Benelux is associated, at least in part, with dietary struvite prophylaxis and dissolution. Whether the recent global trend towards decline of calcium oxalate will be reproduced here remains to be seen. Maintained ratio could be a consequence of less widespread management to reduce risk factors of calcium oxalate or to differences in the cat populations. The continuous preponderance of struvite uroliths in Spain might have resulted from less emphasis on struvite prevention and dissolution.