Ultrastructure of selected struvite-containing urinary calculi from dogs.
OBJECTIVE
To elucidate the ultrastructural details of struvite-containing urinary calculi from dogs.


METHODS
38 specimens were selected from a collection of approximately 13,000 canine urinary calculi: 18 of these were composed entirely of struvite, and 20 consisted of struvite and calcium phosphate (apatite).


METHODS
Qualitative and quantitative analyses of specimens included use of plain and polarized light microscopy, x-ray diffractometry, scanning electron microscopy with backscattered electron imagery, x-ray fluorescence scans, and electron microprobe analysis.


RESULTS
4 textural types were recognized among struvite calculi, and 4 textural types of struvite-apatite calculi were described. Evidences of calculus dissolution were described from 4 calculi studied.


CONCLUSIONS
The presence of small, well interconnected primary pores in struvite-containing urinary calculi from dogs appears to be a significant factor in determining the possible interaction of calculi with changes in the urine composition. The progress of dissolution from the calculus surface to the calculus interior appears to be largely affected by the primary porosity originally present between crystals forming the calculus framework. Apatite was observed to be more resistant to dissolution than struvite.


CONCLUSIONS
The prevalence of fine concentric laminations having low porosity, and the common occurrence of apatite among struvite-containing urinary calculi from dogs may be 2 reasons why the efficacy of dietary and medicinal manipulations in dissolving urinary calculi is greater among cats than it is among dogs.
Domingo-Neumann
R A
RA
Department of Medicine and Epidemiology, School of Veterinary Medicine, University of California, Davis 95616, USA.
Ruby
A L
AL
Ling
G V
GV
Schiffman
P S
PS
Johnson
D L
DL
D000818:Animals; D002130:Calcium Phosphates / Q000032:analysis; D002371:Cat Diseases; D002415:Cats; D004283:Dog Diseases; D004285:Dogs; D004577:Electron Probe Microanalysis; D017616:Magnesium Compounds / Q000032:analysis*; D008855:Microscopy, Electron, Scanning; D010710:Phosphates / Q000032:analysis*; D011048:Polarography; D013052:Spectrometry, X-Ray Emission; D000069877:Struvite; D014545:Urinary Calculi / Q000628:therapy / Q000648:ultrastructure / Q000662:veterinary*; D014961:X-Ray Diffraction
D002130:Calcium Phosphates; D017616:Magnesium Compounds; D010710:Phosphates; C485828:alpha-tricalcium phosphate; C485830:tetracalcium phosphate; C485838:calcium phosphate, monobasic, anhydrous; C020243:calcium phosphate; D000069877:Struvite; C485829:calcium phosphate, dibasic, anhydrous