Comparison of Single, Averaged, and Pooled Urine Protein:Creatinine Ratios in Proteinuric Dogs Undergoing Medical Treatment

Weekly Biological Variation of Urine Protein Creatinine Ratio and Urine Specific Gravity in Healthy Dogs

BACKGROUND

Urine protein-creatinine ratio (UPC) and urine specific gravity (USG) are important measurements in the determination of renal proteinuria and chronic kidney disease. Biological and analytical variation estimates of these analytes to calculate the index of individuality (IoI) and a reference change value (RCV) are important to determine whether a population-based reference interval can be used to detect clinically meaningful changes and facilitate the interpretation of serial measurements.

OBJECTIVE

Determine the biological variation of UPC and USG using calculations of RCV and IoI in healthy dogs.

ANIMALS

Eleven healthy client-owned young adult dogs.

METHODS

Prospective observational study. First-morning urine samples were collected by voiding once weekly for 6 consecutive weeks for batch analysis. Twenty random samples were run in duplicate. Urine protein concentration, urine creatinine concentration, and USG were measured using a colorimetric pyrogallol red molybdate complex, enzymatic Jaffe method, and manual refractometer, respectively. Restricted maximum likelihood estimations were used to determine within-individual, between-individual, and analytical coefficients of variation and calculation of RCV and IoI.

RESULTS

All dogs were non-proteinuric at enrollment (UPC < 0.2) and remained non-proteinuric on subsequent measurements. Urine protein concentration, urine creatinine concentration, UPC, and USG had intermediate individuality. The RCV was 73% for urine protein concentration, 68% for urine creatinine concentration, 31% for UPC, and 3% for USG.

CONCLUSION

Population-based reference intervals for UPC and USG should be interpreted cautiously for single measurements and calculated RCVs should be applied to serial measurements to identify clinically meaningful changes.

Comparison of cystocentesis versus home sampling to determine urinary protein: Creatinine ratio and urine specific gravity in cats

BACKGROUND

Urinalysis is necessary for the diagnostic evaluation of chronic kidney disease in cats. Performing cystocentesis is not always feasible, but data comparing urine obtained by cystocentesis in the clinic with voided samples collected at home are lacking in cats.

OBJECTIVES

To compare urinary protein:creatinine ratio (UPC) and urine specific gravity (USG) and to detect clinically relevant changes in proteinuria substage or urine concentration between urine collected at home and in-clinic by cystocentesis in cats.

ANIMALS

Ninety-two healthy and diseased client-owned cats.

METHODS

Prospective study. Owners collected voided urine at home and within 1 to 15 hours, cystocentesis was performed in the clinic.

RESULTS

In a subset of motivated owners, 55% succeeded in collecting urine at home. Overall, UPC was higher (mean ±SD difference = 0.09 ±0.22; P < .001) and USG was lower (mean ±SD difference = -0.006 ±0.009; P < .001) in cystocentesis samples than in voided urine. Substantial agreement existed between sampling methods for UPC (weighted к = 0.68) and USG (к = 0.64) categories. A different proteinuria substage (UPC < 0.2, 0.2-0.4, >0.4) was present in paired urine samples from 28% of cats. In 18% of cats, urine concentrating ability (USG < or ≥1.035) differed between both samples.

CONCLUSIONS AND CLINICAL IMPORTANCE

Home sampling of urine is a valid alternative to cystocentesis in cats. However, because clinically relevant differences in UPC and USG were present in 28% and 18% of cats, respectively, by the same collection method for monitoring each cat is advised.

Efficacy of a micronized, nanocrystal fenofibrate formulation in treatment of hyperlipidemia in dogs

Background

Safe, effective, and readily available drug therapies are required for the management of hyperlipidemia and its associated complications in dogs.

Objectives

To investigate the efficacy of a micronized, nanocrystal formulation of fenofibrate (Tricor) in the treatment of hyperlipidemia in dogs.

Animals

Ten client‐owned dogs with primary (n = 7) and secondary (n = 3) hyperlipidemia. All dogs had hypertriglyceridemia at baseline; 3 dogs also had hypercholesterolemia.

Methods

Prospective dose‐escalation study. Dogs were treated with fenofibrate orally once daily in up to 3 cycles of 21 days each. Fenofibrate dose was increased at the end of each cycle if hypertriglyceridemia persisted and adverse effects were not documented. Complete blood count, biochemistry, and urine protein:creatinine ratio were collected serially. Baseline (T0) parameters were compared to time of maximal reduction in serum triglyceride concentrations (T1) and reported as median (range).

Results

Triglycerides normalized in all dogs (T0 = 662 mg/dL [189‐2391]; T1 = 113 mg/dL [81‐132]; P = .002). Fenofibrate dose at T1 = 6.4 mg/kg PO q24h (range, 2.2‐13.5). T1 was achieved at 3 (n = 4), 6 (n = 4), and 9 (n = 2) weeks. Serum cholesterol concentrations decreased in 9 of 10 dogs. Quiet demeanor and firm stools in 1 dog were the only reported adverse reactions. Fenofibrate administration resulted in a significant reduction in median alkaline phosphatase activity (P = .049).

Conclusions and Clinical Importance

Over 21 to 63 days, TriCor was effective in the management of primary and secondary hyperlipidemia in dogs.

Treatment of proteinuria in dogs with telmisartan: A retrospective study

Background

Use of telmisartan for the treatment of proteinuria in dogs has not been thoroughly investigated.

Hypothesis/Objectives

Telmisartan can be effective for the treatment of proteinuria in dogs.

Animals

Forty‐four client‐owned dogs with proteinuria.

Methods

Retrospective study. Dogs diagnosed with clinically relevant proteinuria (nonazotemic dogs with a urine protein‐to‐creatinine ratio [UPC] ≥2 and azotemic dogs with UPC ≥0.5) were separated into 3 groups: telmisartan alone, with benazepril, or with mycophenolate. The UPC was recorded before treatment and at subsequent follow‐ups (1, 3, 6, and 12 months, as available). Response to treatment was categorized as complete (UPC ˂0.5), partial (UPC decreased by ≥50% but still ≥0.5), or no response (UPC decreased by <50%). Serum creatinine and potassium concentrations and arterial pressure also were recorded.

Results

In the telmisartan group, treatment response (UPC ˂0.5 or decreased by ≥50%) was observed in 70%, 68%, 80%, and 60% of dogs at 1, 3, 6, and 12 months follow‐up, respectively. No significant changes were noted in serum creatinine or potassium concentrations, or in arterial blood pressure at all follow‐up times. Adverse effects consisted of mild self‐limiting gastrointestinal signs in 5 dogs. Two dogs developed clinically relevant azotemia that required discontinuation of the treatment before the first follow‐up.

Conclusions and Clinical Importance

Telmisartan can be considered for treatment of proteinuria in dogs, alone or in combination with other treatments for proteinuria.

Association between vitamin D metabolites, vitamin D binding protein, and proteinuria in dogs

BACKGROUND

Proteinuria has been associated with progression of renal disease and increased morbidity and mortality in dogs and people. In people, proteinuria also has been associated with hypovitaminosis D. Little is known about the relationship between vitamin D metabolism and proteinuria in dogs.

OBJECTIVES

To further elucidate vitamin D status in dogs with protein-losing nephropathy (PLN) and minimal to no azotemia. We hypothesized that vitamin D metabolites would be lower in dogs with PLN compared to healthy dogs.

ANIMALS

Twenty-three client-owned adult dogs with PLN and 10 healthy control dogs.

METHODS

Serum 25-hydroxyvitamin D (25[OH]D), 1,25-dihydroxyvitamin D (1,25[OH]₂ D), 24,25-dihydroxyvitamin D (24,25[OH]₂ D), serum vitamin D binding protein (VDBP), and urine 25(OH)D concentrations were measured.

RESULTS

Compared to healthy dogs, dogs with PLN had lower concentrations of all vitamin D metabolites (P < .01). Correlations (rho; 95% confidence interval [CI]) in dogs with PLN are reported. Serum 25(OH)D and 24,25(OH)₂ D concentrations were positively correlated with albumin (r = 0.47; 0.07-0.74), and 24,25(OH)₂ D was negatively correlated with urine protein-to-creatinine ratio (UPC; r = -0.54; -0.78 to -0.16). Urine 25(OH)D-to-creatinine ratio was negatively correlated with serum albumin concentration (r = -0.77; -0.91 to -0.50) and positively correlated with UPC (r = 0.79; 0.53-0.91). Serum VDBP concentration was positively correlated with serum albumin concentration (r = 0.53; 0.05-0.81).

CONCLUSIONS AND CLINICAL IMPORTANCE

Dogs with PLN have decreased serum concentrations of vitamin D metabolites. Urine 25(OH)D-to-creatinine ratio and UPC are correlated in PLN dogs. Future studies are needed to assess additional management strategies for dogs with PLN.

Clinicopathologic characteristics, pathology, and prognosis of 77 dogs with focal segmental glomerulosclerosis

BACKGROUND

Focal segmental glomerulosclerosis (FSGS) is a common cause of nonimmune complex glomerulopathy and the prognosis and clinicopathologic findings associated with this condition have not been described in dogs.

OBJECTIVE

To characterize the presentation and identify clinical factors associated with the survival of dogs with FSGS.

ANIMALS

Seventy-seven dogs diagnosed with FSGS based on evaluation of renal biopsy samples submitted to the International Veterinary Renal Pathology Service.

METHODS

Retrospective review of medical records of dogs biopsied for evaluation of proteinuria between January 2015 and May 2017.

RESULTS

The incidence of FSGS among all dogs biopsied for proteinuria was 26%. Significantly more females (48; 62.3%) than males (29; 37.7%) were affected (P = .04). At the time of biopsy, median serum creatinine concentration (SCr) was 1.2 mg/dL (range, 0.3-8.7), median serum albumin concentration (Alb) was 2.8 g/dL (range, 1.1-4.6), median systolic blood pressure was 153.5 mm Hg (range, 95-260), and median urine protein : creatinine ratio was 5.9 (range, 1.4-22). Median survival time after biopsy was 258 days (range, 26-1003) for dogs that died from all causes (n = 32). Factors that were associated with a shorter survival time included SCr ≥ 2.1 mg/dL (P < .01) and Alb < 2 g/dL (P < .01).

CONCLUSIONS AND CLINICAL IMPORTANCE

Most dogs with FSGS were female, and although commonly hypertensive, azotemia, severe hypoalbuminemia and ascites or edema were observed infrequently. Variables significantly associated with survival time were SCr and Alb.

Urine cortisol-creatinine and protein-creatinine ratios in urine samples from healthy dogs collected at home and in hospital

Background

Recently, urine protein:creatinine ratios (UPC) were shown to be lower in urine samples from dogs collected at home (AH) as compared to those collected in hospital (IH). Stress‐inducing procedures and travel to the hospital have been hypothesized to cause prerenal proteinuria.

Objectives

Evaluate patient stress using urine cortisol:creatinine ratios (UCCr) and correlate UCCr to UPC in urine samples obtained AH and IH.

Animals

Thirty‐six healthy, client‐owned dogs.

Methods

Prospective, non‐masked study. Two voided urine samples were obtained (AH and IH). Complete urinalysis as well as UPC and UCCr were performed. Clients graded their dogs' stress level AH, in transport, and IH.

Results

The UCCr was significantly higher in IH samples than in AH samples (P < .0001), but UPC was not significantly different between AH and IH urine samples (P = .14). In all samples and in both collection settings, UCCr was not significantly correlated with UPC. Travel time and time IH were not correlated with change in UCCr or UPC. In 8 dogs with borderline or overt proteinuria, no significant difference was found in UPC between settings, but UCCr was significantly higher in IH samples.

Conclusions and Clinical Importance

The UPC was not higher when measured in urine samples collected IH compared to AH. Dogs had higher UCCr IH, but UCCr was not associated with UPC. Stress, as estimated by UCCr, did not affect proteinuria. Further evidence is needed to support the claim that stress may result in proteinuria in healthy dogs.