The chemical composition and ultrastructure of uroliths in Boer goats.

The chemical composition and ultrastructure of urinary calculi obtained from male Boer goats were studied using qualitative chemical analysis, scanning electron microscopy, X-ray diffraction, X-ray energy dispersive spectrometry and Fourier transform infra-red spectroscopy. The calculi came from 10 naturally-occurring cases of urolithiasis and from seven cases of urolithiasis experimentally-induced by feeding a cottonseed meal-rice straw diet supplemented with magnesium oxide. The results indicated that the major component of urinary calculi collected from naturally-occurring and experimentally-induced cases of urolithiasis was struvite (magnesium ammonium phosphate). The study also identified previously unreported prismatic crystals in the uroliths of goats, similar to struvite but rich in potassium. The characteristic ultrastructure of struvite uroliths is described along with a brief discussion of their formation.