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  • Author or Editor: Peter S. Schiffman x
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Abstract

Objective—To characterize the texture, mineralogic features, and chemical features of enteroliths obtained from horses.

Sample Population—Enteroliths from 13 horses with colic.

Procedure—Enteroliths were harvested from 13 horses that underwent ventral midline celiotomy for treatment of colic or necropsy because of colonic obstruction and rupture caused by enteroliths. Dietary and environmental history were determined via questionnaires or evaluation of medical records. In 7 horses that underwent surgical treatment for enterolithiasis, samples of colonic contents were obtained via an enterotomy in the pelvic flexure. Colonic concentrations of magnesium (Mg), phosphorus (P), sulfur (S), sodium (Na), calcium (Ca), and potassium (K) were determined. Enteroliths were analyzed via electron microprobe analysis and X-ray diffraction.

Results—Enteroliths varied widely regarding degree of porosity, presence and distribution of radiating texture, and composition and size of the central nidus. A distinct concentric banding was identifiable in all enteroliths. Struvite was the predominant component of all enteroliths, although Mg vivianite was identified in 5 enteroliths, and there were variable quantities of Na, S, K, and Ca in the struvite within enteroliths. Despite an abundance of Ca in colonic fluids, Mgphosphate minerals were preferentially formed, compared with Ca-phosphates (apatite), in equine enteroliths.

Conclusions and Clinical Relevance—Enteroliths comprise 2 major Mg phosphates: struvite and Mg vivianite. There is wide variability in macrotexture and ionic concentrations between and within enteroliths. (Am J Vet Res 2001;62:350–358)

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in American Journal of Veterinary Research

Abstract

Objective—To elucidate the ultrastructural details of calcium oxalate-containing urinary calculi from dogs.

Sample Population—38 specimens selected from a collection of 8,297 oxalate-containing urinary calculi from dogs: 22 specimens composed of calcium oxalate (calcium oxalate monohydrate [COM], calcium oxalate dihydrate [COD], or COM and COD) and 16 specimens composed of calcium oxalate with amorphous calcium phosphate.

Procedure—Analyses of specimens included use of plain, reflected, and polarized light microscopy, X-ray diffractometry, scanning electron microscopy (SEM) with backscattered electron (BSE) imagery, and electron microprobe analysis.

Results—Four texture types were observed in calcium oxalate calculi; 4 texture types of calcium oxalatecalcium phosphate-mixed calculi were recognized. Texture types were delineated through differences in calcium oxalate crystal sizes, which were affected by urine supersaturation and abundance of crystal nucleation sites. Segregation of calcium oxalate from calcium phosphate indicated they do not precipitate under the same conditions. Deposition of calcium phosphate between calcium oxalate crystals decreased the volume of pore spaces within calculi. Porosity was observed along boundaries between COM and COD. Minute pores increased the surface area of calculi exposed to urine, and this increase in liquid-solid interface promotes interaction of crystals with the surrounding urine.

Conclusions and Clinical Relevance—Calcium oxalate urolithiasis is of major concern, because it is often a recurrent disease among dogs, principally treated by surgical removal of calculi, with few effective dissolution strategies. Understanding the ultrastructure and mineralogic content of calcium oxalate and its association with amorphous calcium phosphate is a step toward the solution of this increasingly important medical problem. (Am J Vet Res 2001;62:237–247)

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in American Journal of Veterinary Research

Abstract

Objective

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

Sample Population

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).

Procedure

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.

Clinical Relevance

The prevalence of fine concentric laminations having low porosity, and the common occur-rence 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. (Am J Vet Res 1996;57:1274-1287)

Free access
in American Journal of Veterinary Research

Abstract

Objective

To elucidate the ultrastructural details of struvite-containing urinary calculi from cats.

Design

Specimens studied were inclusive of the range of textures visible during preliminary analysis by use of a stereoscopic dissecting microscope. Textural types, which were used to infer crystal growth conditions, were differentiated with regard to crystal habit, crystal size, growth orientation, and primary porosity.

Sample Population

Thirty specimens were selected from a collection of approximately 1,600 feline urinary calculi: 20 of these were composed entirely of struvite, and 10 consisted of struvite and calcium phosphate (apatite).

Procedure

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 probe microanalysis.

Results

Four textural types were recognized among struvite calculi, whereas 2 textural types of struvite-apatite calculi were described.

Conclusions

The presence of minute, well interconnected primary pores in struvite-containing urinary calculi from cats is an important feature, which may promote possible interaction of calculi with changes in urine composition.

Clinical Relevance

Primary porosity, which can facilitate interaction between the calculus and changing urine composition, may explain the efficacy of dietary or medicinal manipulations to promote the dissolution of struvite-containing uroliths from this species. (Am J Vet Res 1996;57:12–24)

Free access
in American Journal of Veterinary Research