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  • Author or Editor: Delmar R. Finco x
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Abstract

Objective—To compare glomerular filtration rate (GFR) measured via urinary clearance of inulin (UCI) with plasma clearance of technetium Tc 99m pentetate (99mTc-pentetate) and creatinine in dogs.

Animals—6 healthy Beagles and 18 Beagles with reduced renal function.

Procedure—13 blood samples were obtained between 5 and 600 minutes after IV bolus injections of 99mTc-pentetate and creatinine. Plasma clearance of 99mTc-pentetate was computed on the basis of 1, 2, or 13 samples, and plasma clearance of creatinine was computed on the basis of 2, 5, or 13 samples. During plasma clearance procedures, constant IV infusion of carboxyl carbon 14 inulin was begun and UCI was determined in urine collected from 90 to 120, 120 to 180, and 180 to 240 minutes. Clearance procedures were repeated in 12 dogs to evaluate reproducibility of results.

Results—Significant association between UCI and plasma clearance was determined via all methods. However, plasma clearances were moderately to markedly different from UCI, depending on test substance, GFR, and sample numbers used for plasma clearance computations. Comparisons were particularly discordant when some methods of limiting samples were used to define plasma clearance.

Conclusions and Clinical Relevance—Values derived from plasma clearance methods for 99mTc-pentetate and creatinine were not interchangeable with UCI results, which raises questions about their reliability as clinical research tools for measurement of GFR. Plasma clearance methods that are relative indices of renal function should not be interpreted as accurate measures of GFR without validation. (Am J Vet Res 2005;66:1046–1055)

Full access
in American Journal of Veterinary Research

Summary

Effects of a protein meal (2.7 g of casein/kg of body weight) on glomerular filtration rate (gfr) and renal plasma flow (rpf) were assessed in dogs after 15/16 nephrectomy (n = 10), and were compared with observations in dogs with intact kidneys (n = 5). Increase in gfr and rpf was observed in both groups of dogs between 1.5 and 8 hours after protein ingestion. A maximal value for gfr was observed between 4 and 5 hours after protein ingestion in dogs of both groups. Enhancement of urinary protein excretion was evident in partially nephrectomized dogs after protein ingestion (P < 0.05), a result that was confirmed by 24-hour total urine collection from partially nephrectomized dogs fed a balanced ration.

A qualitatively similar vasodilatory response was observed in partially nephrectomized dogs and in dogs with intact kidneys, and the mean maximal increase of gfr and rpf expressed as a percentage of baseline values in the latter dogs (47.0 ± 8.1 and 43.6 ± 10.3%, respectively) exceeded that observed in partially nephrectomized dogs (20.8 ± 2.2 and 22.7 ± 6.3%, respectively; P < 0.01). The incremental response of the kidneys to protein ingestion was directly related to the degree of renal function, as reflected in the linear regression relationship between the incremental increase in gfr and the baseline value for gfr (P < 0.01, R 2 = 0.721).

Free access
in American Journal of Veterinary Research

Abstract

Objective

To evaluate utility of a method for estimating glomerular filtration rate after a single IV injection of inulin.

Animals

Cats that were renal intact (n = 3) or had renal mass reduced by partial nephrectomy (n = 6).

Procedure

Plasma clearance of inulin (PCIn) was taken as the quotient of the administered dose of inulin (150 mg) divided by the area under the plasma inulin concentration versus time curve determined by 3 methods (PCIn1 – PCIn3). Results for PCIn were compared with simultaneously obtained values for urinary clearance of exogenous creatinine (CCr), an accepted method for the estimation of glomerular filtration rate (GFR) in cats.

Results

Values for PCIn were closely related (R 2 ranged from 0.951 to 0.972, P < 0.0001 in all instances) to CCr. However, PCIn3 provided an estimate of GFR that consistently overestimated CCr.

Conclusion

Determination of PCIn by use of PCIn1 and PCIn2 provided a reliable estimate of GFR in cats of this study.

Clinical Relevance

Determination of PCIn appears to provide a reliable estimate of GFR in cats with early-stage renal disease and no evidence of derangement of body fluid status. In particular, PCIn2, which requires only 3 determinations of plasma inulin concentration, should be considered when an estimate of GFR is sought in a cat with suspected early-stage renal disease. (Am J Vet Res 1996;57:1702–1705)

Free access
in American Journal of Veterinary Research

SUMMARY

In 6 female goats, the mean threshold for glucosuria was 159.5 ± 4.3 mg/dl. During increasing filtered loads of glucose, renal reabsorption of glucose reached maximal capacity, which was not exceeded when plasma glucose concentration was increased further. Measured in 10 female goats, the transport maximum for glucose was 119.1 ± 9.1 mg of glucose reabsorbed/min. During infusion of glucose, there was a significant (P < 0.05) time-dependent reduction in inulin clearance indicating that IV glucose administration may be inappropriate in goats with compromised renal function.

Free access
in American Journal of Veterinary Research

Summary

Renal clearance procedures were performed on adult mixed-breed dogs with a wide range of renal function. Endogenous creatinine clearance was computed after analyzing plasma and urine for creatinine by use of 2 methods, PAP and kinetic Jaffe. For 20-minute clearance procedures, [14C]inulin clearance was measured simultaneously with endogenous creatinine clearance.

For 111 twenty-minute clearance procedures performed on 24 dogs, [14C]inulin clearance was highly correlated with creatinine clearance for both methods of creatinine analysis (R 2 = 0.979 for [14C]inulin-PAP; R 2 = 0.943 for [14C]inulin-Jaffe). The absolute values for PAP and [14C]inulin clearance were nearly the same (PAP-to-[14C]inulin clearance ratio = 1.03 ± 0.08), but those for Jaffe clearance were substantially less than those for [14C]inulin clearance (Jaffe-to-[14C]inulin clearance ratio = 0.88 ± 0.10).

The Jaffe-to-[14C]inulin clearance ratio was inversely correlated with degree of renal function (R 2= 0.464), whereas the PAP-to-[14C]inulin clearance ratio was not correlated with degree of renal function (R 2 = 0.060). Thus, Jaffe-determined creatinine clearance varied, in relation to [14C]inulin clearance, depending on degree of renal function.

In 4 clinically normal dogs, 20-minute and 24-hour sample collections analyzed by use of the PAP method gave clearance values significantly greater, for both periods, than did Jaffe analyses. The PAP-determined creatinine clearance values were less than, but not significantly different from 20-minute exogenous creatinine clearance values determined 10 days after 24-hour collections.

For 20-minute and 24-hour collections, the difference in clearance values between the PAP and Jaffe methods was attributable mostly to lower plasma creatinine values for the PAP method (mean ± SEM, plasma PAP-to-Jaffe ratio = 0.798 ± 0.053). However, urine creatinine values also were less by use of the PAP method (urine PAP-to-Jaffe ratio = 0.943 ± 0.103).

We conclude that PAP-determined creatinine clearance reliably measured glomerular filtration rate during 20-minute collections, and probably during 24-hour collections as well. By contrast, Jaffe-determined creatinine clearance underestimated glomerular filtration rate by a variable amount.

Free access
in American Journal of Veterinary Research

Summary

Clinically normal dogs were evaluated in states of dehydration, euhydration, and after fluid administration to determine effects of hydration state on renal clearance values. Endogenous creatinine, exogenous creatinine, and [14C]inulin clearances, were determined to measure glomerular filtration rate (gfr); in some experiments p-aminohippurate clearance was determined to measure renal plasma flow.

Dehydration caused significant (P < 0.05) decrease in clearance values, compared with euhydration, and clearance values during euhydration were significantly (P < 0.05) less than values obtained after a single gavage with water (30 ml/kg of body weight).

Sustained administration of 3 fluid regimens was evaluated for effects on clearance values (treatment A = 30 ml of lactated Ringer’s solution/kg/h; treatment B = 30 ml of water/kg by gavage hourly; treatment C = 10 ml of glucose:lactated Ringer’s solution/kg/h). All regimens of fluid therapy caused significant P < 0.05), progressive increases in gfr, but treatment C resulted in the most stable gfr values. Increases in clearance values were associated with positive fluid balance; the rate of fluid administration was greater than the rate of urine formation.

Data from 285 gfr determinations on 85 dogs were evaluated retrospectively. For each determination, three 20-minute urine collections were made beginning 40 minutes after 30 ml of water/kg was given by gavage. Values between collections were significantly (P < 0.05) different, but varied by < 3%.

Comparison of methods for measurement of gfr indicated that endogenous creatinine clearance and [14C]inulin clearance were highly correlated (R 2 = 0.82), but mean clearance values were markedly different (mean ± sem, 28.70 ± 0.01 and 37.07 ± 1.29 ml/min, respectively).

Exogenous creatinine clearance and [14C]inulin clearance were highly correlated (R 2 = 0.95), and mean values were 40.54 ± 0.70 and 41.02 ± 0.70 ml/min respectively.

We conclude that: state of hydration has a marked effect on gfr; rate of fluid administration that exceeds rate of urine production results in progressive increases in gfr; a single water gavage of 30 ml/kg gives stable gfr values for three 20-minute collection periods, may avoid subclinical states of dehydration, and facilitates accurate urine collections; and endogenous creatinine clearance, as conducted in this study, does not accurately measure gfr.

Free access
in American Journal of Veterinary Research

Summary

Renal mass was surgically reduced in 78 dogs by uninephrectomy or by combined renal infarction and uninephrectomy. Renal clearance of inulin and renal clearance of exogenous creatinine were determined simultaneously, and the creatinine to inulin clearance (c/i) ratio was calculated. Clearance procedures were performed 2 to 3 months after reduction of renal mass, and were repeated at intervals thereafter. Overall, the c/i ratio was 1.008 ± 0.007 for 192 determinations, with a highly significant correlation (R2 = 0.994, P < 0.0001) between creatinine clearance and inulin clearance. There was no significant effect of gender of dogs, time after partial renal ablation, or dietary protein intake on c/i ratios. Degree of renal ablation did not affect c/i ratios. The results indicated that exogenous creatinine clearance is a valid measure of glomerular filtration rate in both male and female dogs with reduced renal mass.

Free access
in American Journal of Veterinary Research

SUMMARY

Excretion of creatinine, sodium sulfanilate (ss), and phenolsulfonphthalein (psp) was studied in healthy goats. In conscious goats, mean (± sem) inulin clearance was 2.26 ± 0.08 ml/min/kg of body weight. Endogenous creatinine clearance, 1.97 ± 0.09 ml/min/kg, underestimated inulin clearance (P < 0.01), probably because of the presence of noncreatinine chromogens in caprine plasma. The estimated renal clearance of psp was 6.88 ± 0.39 ml/min/kg, whereas the estimated renal clearance of ss was 3.71 ± 0.39 ml/min/kg. Both exceeded inulin clearance (P < 0.01), confirming renal tubular secretion of both compounds.

In 6 anesthetized goats, exogenous creatinine clearance and ss clearance exceeded inulin clearance (P < 0.05). Results of stop-flow experiments documented secretion of creatinine and ss by the proximal portion of the caprine nephron.

Plasma half-life of psp in uninephrectomized goats exceeded that in intact goats (20.2 ± 1.5 min vs 11.9 ± 0.7 min; P < 0.01). Similarly, plasma half-life of ss was greater in goats after uninephrectomy (58.2 ± 6.2 min vs 30.4 ± 1.2 min; P < 0.01).

Free access
in American Journal of Veterinary Research

Abstract

Objective—To determine owner impressions of 3 premium canine diets when factors such as price and retail source were removed; to compare body condition scores (BCSs) assigned by owners versus a veterinarian; and to determine consistency of owner impressions of diets when owners were not informed that they were feeding the same diet during 2 consecutive periods.

Design—Randomized controlled trial.

Animals—44 healthy adult dogs.

Procedure—During the initial 12 months of the study, dogs were each fed 3 premium diets for 4 months in random order. After feeding each diet for 1 and 4 months, owners completed questionnaires regarding palatability of the diet; the dog's attitude, energy level, fecal consistency, frequency of defecation, hair coat quality, and BCS; and whether they would feed the diet if available commercially. During the last 4 months of the study, owners fed the same diet they had been feeding during the previous 4 months.

Results—Scores for most variables did not differ among diets. However, mean BCS assigned by owners was significantly lower than mean BCS assigned by an investigator, with a moderate correlation between scores. When asked at the end of the third and fourth study periods whether they would consider feeding the diet long-term, 12 of the 44 (27%) owners gave inconsistent responses.

Conclusions and Clinical Relevance—Results indicate that when unaware of retail price and source, owners have similar impressions of 3 premium diets fed to healthy adult dogs, suggesting that factors other than the diets themselves may affect owner impressions. Owners also underestimate their dog's BCS. (J Am Vet Med Assoc 2005;227:1931–1936)

Full access
in Journal of the American Veterinary Medical Association

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