Search Results

You are looking at 1 - 7 of 7 items for

  • Author or Editor: Tanya A. Cooper x
  • Refine by Access: All Content x
Clear All Modify Search

Abstract

Objective—To determine whether the angiotensin converting enzyme inhibitor enalapril would lower systemic arterial and glomerular capillary pressure and reduce the magnitude of renal injury in a canine model of renal insufficiency.

Animals—18 adult dogs that had renal mass reduced by partial nephrectomy.

Procedure—After surgical reduction of renal mass and baseline measurements, dogs in 2 equal groups received either placebo (group 1) or enalapril (0.5 mg/kg, PO, q 12 h; group 2) for 6 months.

Results—Values for systemic mean arterial blood pressure determined by indirect and direct measurement after 3 and 6 months of treatment, respectively, were significantly lower in group 2 than in group 1. During treatment, monthly urine protein-to-creatinine ratios were consistently lower in group 2 than in group 1, although values were significantly different only at 3 months. At 6 months, significant reduction in glomerular capillary pressure in group 2 was detected, compared with group 1, but glomerular filtration rate in group 2 was not compromised. Glomerular hypertrophy, assessed by measurement of planar surface area of glomeruli, was similar in both groups. Glomerular and tubulointerstitial lesions were significantly less in group 2, compared with group 1.

Conclusions and Clinical Relevance—Data suggest that inhibition of angiotensin converting enzyme was effective in modulating progressive renal injury, which was associated with reduction of glomerular and systemic hypertension and proteinuria but not glomerular hypertrophy. Inhibition of angiotensin converting enzyme may be effective for modulating progression of renal disease in dogs. (Am J Vet Res 2003;64:321–327)

Full access
in American Journal of Veterinary Research

Abstract

Objective

To determine effects of dietary protein and calories on progression of induced chronic renal failure in cats.

Animals

28 young adult female cats.

Procedure

Renal mass was reduced surgically, and glomerular filtration rate (GFR) was determined. Cats were allotted to 4 groups of 7 with similar mean GFR (1.52 to 1.55 ml/min/kg of body weight). Diets were formulated to provide: low protein and calorie (diet A), low protein and high calorie (diet B), high protein and low calorie (diet C), and high protein and calorie (diet D) intakes. Cats were fed their prescribed diet for 12 months, then blood and urine biochemical variables were measured, after which kidney specimens were examined microscopically.

Results

Protein intake by cats of groups C and D (9.0 g/d/kg) was substantially greater than that by cats of groups A and B (5.3 and 5.2 g/d/kg, respectively). Caloric intake by cats of groups B and D (73 and 71 calories/d/kg, respectively) was greater than that by cats of groups A and C (58 and 55 calories/d/kg, respectively). Renal glomerular lesions were mild and not affected by protein, calories, or their interactions. Nonglomerular lesions, though mild, were significantly influenced by calorie intake, but not by protein or calorie-protein interactions. The GFR did not decrease in any group. Urine protein-to-creatinine ratio increased significantly in all groups after reduction of renal mass, but values from all groups remained within the reference range (0 to 0.3).

Conclusions and Clinical Relevance

Diets replete in protein were not associated with increased severity of glomerular or nonglomerular renal lesions, increased proteinuria, or decreased GFR. Diets replete in calories were not associated with increased severity of glomerular lesions, but were associated with mild increase of nonglomerular lesions. Factors other than protein and calorie intake must be considered potential causes of progression of renal failure in cats. Results raise questions about the practice of restricting quantity of protein in the diet of cats with chronic renal failure, with the intention of ameliorating development of further renal damage. (Am J Vet Res 1998;59:575–582)

Free access
in American Journal of Veterinary Research

Summary

Six parathyroidectomized (ptx) and 6 control dogs had renal mass reduced by 15/16, and were studied for effects of parathyroid hormone depletion on progression of renal failure. All ptx dogs and 4 of 6 control dogs survived until necropsy after 32 weeks.

Plasma parathyroid hormone concentration was undetectable in ptx dogs throughout the study, but was greater than normal in control dogs. Serum inorganic phosphate (P) concentration was increased in ptx dogs (6.8 ±0.1 mg/dl) and in control dogs (7.5 ± 0.2), but did not differ significantly (P = 0.254) between groups. Ionized blood calcium values (Ca2+) were significantly (P = 0.014) lower in ptx dogs (1.31 ± 0.01 mmol/L) than in control dogs (1.36 ± 0.00 mmol/L), but were more variable in ptx dogs.

Values in ptx dogs were not significantly different from those in control dogs for glomerular filtration rate (P = 0.914), plasma creatinine concentration (P = 0.903), and urine protein to creatinine ratio (P = 0.756) determined at intervals during the study. Terminal glucose tolerance and plasma insulin concentrations, P tolerance, and renal P excretion did not differ between groups.

Histologic comparison of kidneys removed during reduction of renal mass with kidneys removed at necropsy revealed development of lesions in both groups of dogs, and no protective effect from parathyroidectomy.

Mineral analysis of aorta, brain, heart, lungs, and skeletal muscle obtained at necropsy revealed no significant difference between ptx and control groups. Renal cortical calcium concentration was significantly (P < 0.05) greater in kidneys obtained at necropsy than in kidneys obtained during nephrectomy, but ptx did not protect renal cortex from calcium deposition.

Free access
in American Journal of Veterinary Research

SUMMARY

Objective

To determine whether the “spot” method of determining fractional excretion (FE) of electrolytes in cats is accurate.

Animals

5 clinically normal young adult female cats.

Procedure

Cats were acclimated to metabolism cages, and 2 consecutive 72-hour collections of urine were made to determine FE of total calcium, potassium, total magnesium, sodium, and phosphorus by conventional methods, using endogenous creatinine clearance as an estimate of glomerular filtration rate. During collections, small samples of urine were obtained by cystocentesis at 8 am, 3 pm, and 9 pm for determination of FE of the electrolytes by use of the “spot” method.

Results

Values from “spot” determinations were highly variable, compared with 72-hour values, with a high percentage falling outside the range of mean ± 2 SD for 72-hour FE values.

Conclusions and Clinical Relevance

The “spot” method for determining FE is not precise, and if used, caution and judgement should be exercised in interpretation of the results. (Am J Vet Res 1997;58:1184–1187)

Free access
in American Journal of Veterinary Research

Abstract

Objective

To determine the effects of parathyroid hormone (PTH) depletion on dogs with induced chronic renal failure.

Animals

2 groups of 26 mixed-breed dogs of both sexes (13 were parathyroidectomized [PTX] and 13 had sham surgery).

Procedure

After surgical reduction of renal mass and PTX, dogs were selected for a 24-month period of study and monitored for clinical, hematologic, blood biochemical, and organ function status. On development of uremia or after 24 months, dogs were euthanatized, and tissues were examined.

Results

Higher survival rate and smaller decrement in renal function (glomerular filtration rate) were observed in PTX dogs, compared with those that had sham surgery, but values did not reach statistical significance. The PTX dogs remained hypocalcemic during the study and had lower serum Ca2+ × P product values. Regardless of parathyroid state, survivors and fatalities could be separated on the basis of serum Ca2+ × P product values. Parathyroidectomy did not prevent renal deposition of calcium, and renal lesions were poorly correlated with renal cortical calcium concentration. Abnormalities reported in dogs with renal failure, which were attributed to PTH (glucose intolerance, pulmonary hypertension), were not observed in PTX dogs or those that had sham surgery.

Conclusions and Clinical Relevance

PTX had beneficial effects, but these were mediated via changes in mineral homeostasis rather than via direct effects of PTH. Results attributable to PTX were similar to those previously obtained by dietary restriction of phosphate intake. (Am J Vet Res 1997;58:188–195)

Free access
in American Journal of Veterinary Research

Abstract

Objective

To evaluate the utility of a method for estimating glomerular filtration rate (GFR) after single IV administration of iohexol.

Design

The plasma clearance of iodine (PCI), taken as the quotient of the administered dose of iodine (300 to 600 mg of l/kg of body weight) divided by the area under the plasma iodine concentration versus time curve determined by 4 methods (PCI1–PCI4). The results for PCI were compared with simultaneously obtained values for the urinary clearance of exogenously administered creatinine (CCr), a widely accepted method for the measurement of GFR in cats and dogs.

Animals

Cats and dogs that were renal intact (n = 5 cats; n = 1 dog) or had renal mass reduced by partial nephrectomy (n = 5 cats; n = 7 dogs).

Results

Values for PCI were closely related (R 2 values ranged from 0.947 to 0.992; P < 0.0001 in all cases) to CCr. Despite this close correlation between CCr and PCI, the 95% confidence interval for the difference between PCI3 and CCr included values that exceeded 1.4 ml/min/kg, which represents 50% of the mean value for CCr in renal-intact cats.

Conclusions

Determination of PCI provided a reliable estimate of GFR in cats and dogs of this study. However, differences between 1 of the methods (PCI3) and CCr are clinically important, emphasizing the need to use more than simple linear regression analysis and correlation coefficients when attempting to validate new measurement techniques.

Clinical Relevance

The determination of PCI provided a reliable estimate of GFR in cats and dogs of this study. (Am J Vet Res 1996;57:105-110)

Free access
in American Journal of Veterinary Research