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Abstract
Objective—To identify dietary factors in commercially available canned foods associated with the development of calcium oxalate (CaOx) uroliths in dogs.
Animals—117 dogs with CaOx uroliths and 174 dogs without urinary tract disease.
Procedure—Case dogs were those that developed CaOx uroliths submitted to the Minnesota Urolith Center for quantitative analysis between 1990 and 1992 while fed a commercially available canned diet. Control dogs were those without urinary tract disease evaluated at the same veterinary hospital just prior to or immediately after each case dog. A content-validated multiple-choice questionnaire was mailed to each owner of case and control dogs with the permission of the primary care veterinarian. Univariate and multivariate logistic regressions for each dietary component were performed to test the hypothesis that a given factor was associated with CaOx urolith formation.
Results—Canned foods with the highest amount of protein, fat, calcium, phosphorus, magnesium, sodium, potassium, chloride, or moisture were associated with a decreased risk of CaOx urolith formation, compared with diets with the lowest amounts. In contrast, canned diets with the highest amount of carbohydrate were associated with an increased risk of CaOx urolith formation.
Conclusions and Clinical Relevance—Feeding canned diets formulated to contain high amounts of protein, fat, calcium, phosphorus, magnesium, sodium, potassium, chloride, and moisture and a low amount of carbohydrate may minimize the risk of CaOx urolith formation in dogs. (Am J Vet Res 2002;63:163–169)
Abstract
Objective—To identify factors in dry diets associated with the occurrence of calcium oxalate (CaOx) uroliths in dogs.
Animals—600 dogs with CaOx uroliths and 898 dogs without urinary tract diseases.
Procedure—Univariate and multivariate logistic regression were performed.
Results—Compared with diets with the highest concentrations of sodium, dry diets with the lowest concentrations of sodium, phosphorus, calcium, chloride, protein, magnesium, or potassium were linearly associated with increased risk of CaOx urolith formation. Significant nonlinear associations between increased occurrence of CaOx uroliths and urine acidifying potential and low moisture content were observed. Significant nonlinear associations between decreased occurrence of CaOx uroliths and carbohydrate and fiber contents were observed. A significant association between the occurrence of CaOx uroliths and dietary fat was not observed.
Conclusions and Clinical Relevance—Results suggest that dry diets formulated to contain high concentrations of protein, calcium, phosphorus, magnesium, sodium, potassium, and chloride may minimize formation of CaOx uroliths. In addition, comparison of risk and protective factors of various diet ingredients fed to dogs with CaOx uroliths suggests that although similar findings were observed in canned and dry formulations, in general, greater risk is associated with dry formulations. However, before these hypotheses about dietary modifications are adopted by food manufacturers, they must be investigated by use of appropriately designed clinical studies of dogs with CaOx urolithiasis. (Am J Vet Res 2002;63:330–337)
Abstract
Objectives
To determine bioavailability and pharmacokinetic parameters for allopurinol and its active metabolite, oxypurinol.
Animals
6 healthy, reproductively intact female Beagles, 4.9 to 5.2 years old, and weighing 9.5 to 11.5 kg.
Procedure
In the first part of the study, allopurinol was administered IV at a dosage of 10 mg/kg of body weight to 3 dogs and 5 mg/kg to 3 dogs; the sequence was then reversed. In the second part of the study, allopurinol was administered orally at a dosage of 15 mg/kg to 3 dogs and 7.5 mg/kg to 3 dogs; the sequence was then reversed. In the third part of the study, allopurinol was administered IV (10 mg/kg), orally (15 mg/kg) with food, and orally (15 mg/kg) without food. Plasma samples were obtained at timed intervals, and concentrations of allopurinol and oxypurinol were determined.
Results
Maximal plasma allopurinol concentration and area under plasma allopurinol and oxypurinol concentration-time curves were 2 times greater when dogs were given 10 mg of allopurinol/kg IV, compared with 5 mg/kg, and when dogs were given 15 mg of allopurinol/kg orally, compared with 7.5 mg/kg. Allopurinol elimination half-life, time to reach maximal plasma oxypurinol concentration, and oxypurinol elimination half-life were significantly greater when dogs received 10 mg of allopurinol/kg IV, compared with 5 mg/kg, and when dogs received 15 mg of allopurinol/kg orally, compared with 7.5 mg/kg.
Conclusions
Elimination of allopurinol is dependent on nonlinear enzyme kinetics. The bioavailability of allopurinol, and pharmacokinetic parameters of allopurinol and oxypurinol after oral administration of allopurinol, are not affected by administration with food.
Clinical Relevance
A dose threshold exists beyond which additional allopurinol would not substantially further inhibit xanthine oxidase activity. Oral administration of > 15 mg of allopurinol/kg to dogs would not be expected to result in greater reduction of plasma and urine uric acid concentrations. Also, allopurinol may be administered to dogs for dissolution or prevention of urate uroliths without regard to time of feeding. (Am J Vet Res 1997;58:504–510)
SUMMARY
Urine activity product ratios of uric acid, sodium urate, and ammonium urate and urinary excretion of metabolites were determined in 24-hour samples produced by 6 healthy Beagles during periods of consumption of a low-protein, casein-based diet (diet A) and a high-protein, meat-based diet (diet B). Comparison of effects of diet A with those of diet B revealed: significantly lower activity product ratios of uric acid (P = 0.025), sodium urate (P = 0.045), and ammonium urate (P = 0.0045); significantly lower 24-hour urinary excretion of uric acid (P = 0.002), ammonia (P = 0.0002), sodium (P = 0.01), calcium (P = 0.005), phosphorus (P = 0.0003), magnesium (P = 0.01), and oxalic acid (P = 0.004); significantly (P = 0.0001) higher 24-hour urine pH; and significantly (P = 0.01) lower endogenous creatinine clearance. These results suggest that consumption of diet A minimizes changes in urine that predispose dogs to uric acid, sodium urate, and ammonium urate urolithiasis.
Abstract
Objective—To investigate the biomechanics of cervical vertebral motion units (VMUs) before and after a ventral slot procedure and after subsequent pin-polymethylmethacrylate (pin-PMMA) fixation and to assess the use of smooth and positive-profile threaded (PPT) pins in pin-PMMA fixation and intravertebral pin placement.
Sample Population—Cervical portions (C3 through C6 vertebrae) of 14 cadaveric canine vertebral columns.
Procedure—Flexion and extension bending moments were applied to specimens before and after creation of a ventral slot across the C4-C5 intervertebral space and after subsequent smooth or PPT pin-PMMA fixation at that site. Data for the C3-C4, C4-C5, and C5-C6 VMUs were compared among treatments and between pin types, and pin protrusion was compared between pin types.
Results—Compared with values in intact specimens, ventral slot treatment increased neutral zone range of motion (NZ-ROM) by 98% at the treated VMUs and appeared to decrease overall ROM at adjacent VMUs; pin-PMMA fixation decreased NZ-ROM by 92% at the treated VMUs and increased overall NZ-ROM by 19% to 24% at adjacent VMUs. Specimens fixed with PPT pins were 82% (flexion) and 80% (extension) stiffer than smooth–pin-fixed specimens. Overall, 41% of pins protruded into foramina; PPT pins were more likely to protrude into transverse foramina.
Conclusions and Clinical Relevance—Results indicated that fixation of a cervical VMU alters the biomechanics of adjacent VMUs and may contribute to degeneration of adjacent intervertebral disks. Use of threaded pins may lower the incidence of pin loosening and implant failure but enhances the likelihood of transverse foramina penetration. ( Am J Vet Res 2005;66:678–687)
Abstract
Objective
To determine the effect of surgical technique and use of a rigid centralizing device on stem positioning and geometric reconstruction in the sagittal plane during total hip replacement in dogs.
Sample Population
Bilateral femurs from 8 adult mixed-breed canine cadavers.
Procedure
Femurs were prepared for femoral stem implantation, using 4 variations in technique. Proximal femoral reconstruction and femoral stem positioning were evaluated on radiographs.
Results
Implants evaluated in this study accurately reconstructed displacement of the femoral head of the intact canine femur in the sagittal plane. Centralization of the distal aspect of the stem was optimized by use of an undersized femoral stem. Ostectomy at the level of the lesser trochanter resulted in the smallest diaphysis-to-implant angle. Anteversion and retroversion of implants significantly decreased the distance between the distal tip of the implant and the adjacent cortex, compared with normoversion. The centralizing device significantly increased the minimum distance between the distal tip of the implant and adjacent cortex but did not improve the odds of actually centralizing the tip of the implant.
Conclusions and Clinical Relevance
Malpositioning of implants in the sagittal plane may be minimized through ostectomy at the lesser trochanter and use of an undersized implant positioned in normoversion. Use of a polymethylmethacrylate centralizing device will help eliminate contact between the implant tip and adjacent cortex. Implantation of an undersized femoral component, avoidance of substantial anteversion or retroversion, and use of a rigid centralizing device are recommended when using the prosthesis described-for total hip replacement of dogs. (Am J Vet Res 1999;60:1126–1135)
Abstract
Objective
To determine whether morphology of single-mineral urocystoliths and age, sex, or breed data could be applied to facilitate radiographic and clinical urocystolith mineral type prediction, respectively, in dogs.
Sample Population
Database of 2,041 dogs with pure mineral composition urocystoliths.
Procedure
All uroliths were characterized according to geologic descriptive terminology and by breed, sex, and age of dog at time of sample submission. Summary statistics were used to compare features with specific mineral types. Observed trends were analyzed for statistical relevance between observed and expected frequencies for age, sex, color, size, shape, and surface, using the null hypothesis that differences by urocystolith mineral type did not exist. On the basis of expected breed occurrence derived by equations, the null hypothesis that urocystolith occurrence paralleled canine breed popularity was tested.
Results
Urocystoliths > 10 mm in any dimension were > 92% likely to be magnesium ammonium phosphate hexahydrate (MAP). Smooth, blunt-edged or faceted, and pyramidal urocystoliths were usually MAP. Jackstone shapes were almost always silica. Botryoidal (grape-like clusters) urocystoliths were likely to be oxalates. Breeds with high relative likelihood of urocystoliths included: English Bulldog, Pekingese, Pug, Welsh Corgi, and West Highland White Terrier. Breeds with low relative likelihood of urocystolith production included: German Shepherd Dog, Shar-Pei, and German Shorthaired Pointer. About 94% of urocystoliths produced in females or spayed females were MAP, whereas males and neutered males produced a greater assortment.
Conclusions and Clinical Relevance
For pure mineral composition urocystoliths, trends in mineral type among breeds and between sexes can be exploited clinically in the diagnosis and management of urolith-related disease. Size and shape, used in conjunction with age, breed, and sex, can facilitate pure urocystolith mineral type prediction. (Am J Vet Res 1998;59:379–387)
SUMMARY
Urine activity product ratios of uric acid (aprua), sodium urate (aprna), and ammonium urate (aprau), and urinary excretion of 10 metabolites were determined in 24-hour urine samples produced by 6 healthy Beagles during periods of consumption of 4 diets containing approximately 11% protein (dry weight) and various protein sources: a 72% moisture, casein-based diet; a 10% moisture, egg-based diet; a 72% moisture, chicken-based diet; and a 71% moisture, chicken-based, liver-flavored diet. Significantly (P < 0.05) higher aprua, aprna, and aprau were observed when dogs consumed the egg-based diet, compared with the other 3 diets; there were no differences in these ratios among the other 3 diets.
Twenty-four-hour urinary excretions of chloride, potassium, phosphorus, and oxalic acid were significantly (P < 0.05) higher when dogs consumed the egg-based diet. Twenty-four-hour urinary excretions of sodium were significantly (P < 0.05) higher when dogs consumed the egg-based diet, compared with the casein-based diet and the chicken-based, liver-flavored diet, but were not significantly different between the egg-based diet and chicken-based diet. Twenty-four-hour urine volume was similar when dogs consumed the 4 diets. Twenty-four-hour endogenous creatinine clearance was significantly (P < 0.05 lower when dogs consumed the casein based diet there were no differences among the other 3 diets. Although consumption all diets was associated with production alkaline urine, the 24-hour urine pH was significantly (P < 0.05) higher when dogs consumed the egg-based diet.
These results suggest that use diets containing approximately 10.5% protein (dry weight) and 70 moisture protocols designed for dissolution and prevention urate uroliths may be beneficial. The source dietary protein in canned formulated diets does not appear significantly influence the saturation of urine with uric acid, sodium urate, or ammonium urate.
Abstract
Objective
To evaluate the influence of 3 diets used to dissolve or prevent ammonium urate uroliths in dogs, and a diet formulated for growth, on 24-hour excretions of uric acid, ammonia, net acid, titratable acid, bicarbonate, and creatinine: 24-hour urine volumes: pH values of 24-hour urine samples; plasma uric acid concentration; serum creatinine concentration; and endogenous creatinine clearance values.
Design
Randomized block.
Animals
Six reproductively intact female Beagles, 3.9 to 4.2 years old, weighing 8.5 to 11.1 kg.
Procedures
Four diets were evaluated for their ability to dissolve magnesium ammonium phosphate hexahydrate (struvite) uroliths (diet S); to minimize uric acid excretion (diet U); to minimize clinical signs associated with renal failure (diet K); and to promote growth in pups (diet P). Each diet was fed for 14 days; then 24-hour urine samples were collected. An adult maintenance diet was fed during a 7-day washout period.
Results
Consumption of diet U was associated with lowest plasma uric acid concentration, lowest 24-hour urinary uric acid, ammonia, titratable acid, and net acid excretions, lowest endogenous creatinine clearance values, highest 24-hour urinary bicarbonate excretion and urine pH values, and highest 24-hour urine volumes. Consumption of diet P was associated with opposite results; results of consumption of diets S and K were intermediate between those for diets U and P.
Conclusion
Consumption of diet U by healthy Beagles is associated with reduced magnitude of urinary excretion of uric acid and ammonia, with alkaluria, and with polyuria, which may be beneficial in the management of ammonium urate uroliths in dogs.
Clinical Relevance
Results support use of diet U for management of ammonium urate urolithiasis in dogs.(Am J Vet Res 1996;57:324-328)
SUMMARY
Casein has been used as a protein source in diets designed to dissolve canine ammonium urate uroliths and to prevent their recurrence, because it contains fewer purine precursors than do many other sources of protein. However, an important question is whether reduced quantities of dietary casein have any benefit in modifying saturation of urine with urates. To answer this question, activity productd ratios of uric acid, sodium urate, and ammonium urate were determined in 24-hour urine samples produced by 6 healthy Beagles during periods of consumption of a 10.4% protein, casein-based (10.4% casein) diet and a 20.8% protein, casein-based (20.8% casein) diet. Significantly lower activity product. ratios of uric acid, sodium urate, and ammonium urate were observed when dogs consumed the 10.4% casein diet. Significantly lower 24-hour urinary excretions of ammonia and phosphorus were observed when dogs consumed the 10.4% casein diet. Twenty-four-hour urinary excretions of magnesium and 24-hour urine pH values were significantly higher when dogs were fed the 10.4% casein diet. These results suggest that use of the 10.4% casein diet in protocols designed for dissolution and prevention of uric acid, sodium urate, and ammonium urate uroliths in dogs may be beneficial.