Background: In 2006 to 2014, 10 cases of urolithiasis in yaks, with calcium carbonate uroliths, were confirmed in Switzerland and at the same time a 6-fold calcium overhang in roughage in an affected farm was shown.
Methods: Blood samples from 99 animals were examined from 10 farms (n=6 problem farms; n=4 control farms). In addition, roughage, soil and water samples were analyzed. The farms are distributed within different regions in Switzerland.
Results: The study revealed different Ca : P ratio from 1.56 to 7.74 : 1 in the forages and mild hypercalcemia in the animals of problem farms. In the univariate analysis, problem versus control farms, about 20 other significant factors emerged. The multivariate analysis has shown that altitude, CP (crude protein), P, Mg, NDF (neutral detergent fibre) and ADF (acid resistant detergent fibre) in the diet are important factors. Based on the analysis of the pedigree there was no evidence for an obvious genetic background of urolithiasis.
Limitations: Limitation is the small number of Yaks in Switzerland.
Conclusion: The question of whether urolithiasis in yaks in alpine Switzerland, poses a husbandry risk, can be answered affirmatively. The calcium-rich forages play a crucial role in this multifactorial process.