Urine protein determination in dogs and cats: comparison of dipstick and sulfasalicylic acid procedures

Protein levels in urine specimens from 91 dogs and 65 cats were evaluated by sulfasalicylic acid precipitation (SSA) and dipstick methods. The dipstick frequently yielded reactions for protein that were greater than the level of protein indicated by SSA (i.e., false positive reactions), although no false negative reactions for protein were noted. All urine specimens with protein levels equal to or greater than 100 mg/dl by SSA had dipstick results of 3 +. Results of this study suggest that dipstick analysis for urine protein is an adequate screening procedure for the selection of urines for quantitative analysis of protein and creatinine to assess proteinuria.     

The Effect of Experimental Cystitis and Iatrogenic Blood Contamination on the Urine Protein/Creatinine Ratio in the Dog

The effect of experimentally induced cystitis and iatrogenic blood contamination on the urine protein/creatinine ratio (U P/C) was evaluated in 17 dogs. Before they were included in the study, all dogs were judged to be healthy on the basis of physical examination, serum concentrations of urea nitrogen and creatinine, complete urinalysis, and a U P/C less than 0.4. A single urine sample was contaminated with increasing quantities of canine fresh whole blood (PCV = 42%; total protein = 6.2 g/dl). When added blood was equal to or greater than 25% of the total urine sample volume, the U P/C exceeded 3.5, a finding consistent with nephrotic range proteinuria. When added blood was 10% of the total urine sample volume, the U P/C was less than 1.8. Eleven Beagles underwent routine laparotomy during which a cystotomy was done. The median U P/Cs on postoperative days 1 and 2 were significantly increased compared with preoperative values (P less than 0.05); no U P/C exceeded 2.0. Renal biopsies performed on postoperative day 3 eliminated renal proteinuria as a source of urine protein. Five dogs had bacterial cystitis experimentally induced. At 72 and 96 hours after bacterial inoculation, the median U P/Cs were significantly increased (P less than 0.05); individual values ranged from 1.5 to 40.8. Renal biopsies performed between 5 and 6 days after inoculation eliminated renal proteinuria as a source of urine protein. Cytologic evaluation of urine sediment in each group did not correlate with the magnitude of the increase in the U P/C. The U P/C significantly increased in each model of lower urinary tract inflammation.(ABSTRACT TRUNCATED AT 250 WORDS)     

Comparison of Multistix PRO dipsticks with other biochemical assays for determining urine protein (UP), urine creatinine (UC) and UP:UC ratio in dogs and cats

BACKGROUND: Urine protein: urine creatinine (UP:UC) ratio determined from the quantitative measurement of protein and creatinine in a single urine sample is the best feasible assessment of clinically significant proteinuria in dogs and cats. A dipstick that measures urine protein, urine creatinine, and UP:UC ratio has been used in human medicine and could have application for veterinary practice. OBJECTIVE: The objective of this study was to compare the Multistix PRO dipstick (Bayer Corporation, Elkhart, IN, USA) to other biochemical methods for determination of urine protein and creatinine, and UP:UC ratio in canine and feline urine. METHODS: A complete urinalysis, including sulfosalicylic acid (SSA) precipitation, was performed on urine samples submitted to our laboratory between February and April 2003 from 100 dogs and 49 cats. Urine protein and creatinine concentrations were determined by the Multistix PRO dipstick using a Clinitek 50 analyzer (Bayer) and compared with the results of SSA precipitation and quantitative biochemical analysis. The UP:UC ratios from the dipstick results (calculated by the Clinitek 50 and also manually) were compared with those calculated from quantitative values. Pearson product-moment correlation analysis and diagnostic sensitivity and specificity (using quantitative results as the gold standard) were determined. RESULTS: For both canine and feline urine, protein and creatinine concentrations determined by the Multistix PRO correlated closely with quantitative concentrations for protein (dogs r = .78, P = .0001; cats r = .87, P = .0001) and creatinine (dogs r = .78, P = .0001; cats r = .76, P = .0001). The Multistix PRO was more sensitive and less specific than SSA precipitation for diagnosing clinically significant proteinuria. UP:UC ratios obtained by manual calculation of dipstick results correlated best with quantitative UP:UC ratios in dogs, and had higher specificity but lower sensitivity for the diagnosis of proteinuria. In cats, UP:UC ratios determined by the dipstick method did not correlate (r = -.24, P = .0974) with quantitative values. CONCLUSIONS: The Multistix PRO, with manual calculation of UP:UC, may be a good alternative for the diagnosis of clinically significant proteinuria in dogs, but not cats. Dipstick creatinine concentration should be considered as an estimate.     

Nitrogen utilization in growing lambs: effects of grain (starch) and protein sources with various rates of ruminal degradation

The potential interaction between grain (starch) and protein sources with varying ruminal degradation rates on N utilization in growing lambs was evaluated. Three grain sources with varying ruminal degradation rates, (barley greater than steam-flaked sorghum [SFSG] greater than dry-rolled sorghum [DRSG]) and three protein sources (urea greater than a 50:25:25 mixture of urea: blood meal:corn gluten meal [N basis, U/BC] greater than 50:50 mixture of meal:corn gluten meal [N basis, BC]), were evaluated in a 3 x 3 factorial arrangement. Supplemental protein sources provided 33% of dietary N (CP = 11.0%). For each grain-protein combination, a 3 x 3 Latin square metabolism trial was conducted using two sets of three lambs and three periods. Within-square treatments were 1.4, 1.7 and 2.0 times maintenance intake levels. No interactions were observed (P greater than .2) between dietary treatments and intake level. Grain sources did not differ (P greater than .2) in N balance or the proportion of N retained. Lambs fed urea diets retained less N (3.6 vs 4.2 and 4.1 g/d for urea vs U/BC and BC, respectively; linear, P = .07; quadratic, P = .12) and utilized N less efficiently (43.1 vs 51.9 and 52.5%, respectively; linear, P less than .001; quadratic, P = .10) than lambs fed BC diets. The grain x protein interaction was significant for most variables. Nitrogen utilization was most efficient (24 to 27% of N intake retained) when rapidly degraded sources (barley and urea) and slowly degraded sources (sorghum and BC) were fed together or when U/BC was the supplemental protein source (interaction P less than .08). An advantage was found for selection of starch and protein sources with similar ruminal degradation rates.     

Ileal and total tract nutrient digestibilities and fecal characteristics of dogs as affected by soybean protein inclusion in dry, extruded diets

Plant-based protein sources are generally less variable in chemical composition than animal-based protein sources. However, relatively few data are available on the nutrient digestibilities of plant-based protein sources by companion animals. The effects of including selected soybean protein sources in dog diets on nutrient digestion at the ileum and in the total tract, as well as on fecal characteristics, were evaluated. Six protein sources were used: soybean meal (SBM), Soyafluff 200W (soy flour), Profine F (traditional aqueous-alcohol extracted soy protein concentrate [SPC 1]), Profine E (extruded SPC [SPC 2]), Soyarich I (modified molecular weight SPC [SPC 3]), and poultry meal (PM). All diets were extruded and kibbled. Test ingredients varied in CP and fat contents; however, diets were formulated to be isonitrogenous and isocaloric. Nutrient intakes were similar, except for total dietary fiber (TDF), which was lower (P < 0.01) for dogs fed the PM diet. Apparent ileal digestibilities of DM, OM, fat, and TDF were not different among treatments; however, CP digestibility at the terminal ileum was higher (P < 0.01) for diets containing soy protein sources than for PM. Total tract CP digestibility was greater (P < 0.01) for soy protein-containing diets than for PM. Apparent total tract digestibilities of DM, OM, fat, and TDF were not different among treatments. Apparent amino acid digestibilities at the terminal ileum, excluding methionine, threonine, alanine, and glycine, were higher (P < 0.01) for soy protein-containing diets than for PM. Dogs fed SPC diets had lower (P < 0.01) fecal outputs (g asis feces/g DMI) than dogs fed the SF diet, and dogs fed SBM tended (P < 0.11) to have lower fecal outputs than dogs fed the SF diet. However, dogs fed the PM diet had lower (P < 0.03) fecal outputs than dogs fed SPC-containing diets. Fecal outputs and scores reflected the TDF and nonstructural carbohydrate contents of the soy protein fraction. Soy protein sources are well utilized by the dog prior to the terminal ileum, and SPC offers a viable alternative to PM as a protein source in dry, extruded canine diets.     

Effects of collection time and food consumption on the urine protein/creatinine ratio in the dog

Effects of collection time and food consumption on the variability of the urine protein/creatinine ratio were determined in 10 healthy dogs. In trial 1, dogs were fasted for 12 hours, and urine specimens were obtained by bladder catheterization every 2 hours over an 8-hour collection period during the day. After a 1-week rest, the dogs were entered into trial 2. Dogs were fed at least 60 kcal of a high protein meal/kg of body weight, and urine specimens were obtained every 2 hours over an 8-hour period during the day. Urine total protein and urine creatinine concentrations and the urine protein/creatinine ratio were determined for each urine specimen obtained. Friedman's 2-way analysis by ranks was used to determine the constancy of this ratio over the 4 periods in the 2 trials (fasted and fed). There was no significant variability (P greater than 0.05) in ratios over the 8-hour collection periods in the fasted or fed trial. Feeding did not significantly alter this ratio, because there was no significant difference (P greater than 0.05) in the urine protein/creatinine ratios of the dogs when they were fasted, compared with those of the dogs when they were fed. Seemingly, urine specimens obtained anytime during the day from dogs in both trials (fasted and fed) reflected the urine protein/creatinine ratio.     

Effects of phosphorus/calcium-restricted and phosphorus/calcium-replete 32% protein diets in dogs with chronic renal failure.

Twenty-four dogs with induced, severe chronic renal failure were allotted to 2 groups of 12 each. Group-A dogs were fed a 0.4% phosphorus (P)/0.6% calcium, 32% protein diet, and group-B dogs were fed a 1.4% P/1.9% calcium, 32% protein diet. Dogs were studied over 24 months to determine clinical status, survival, blood biochemical alterations, glomerular filtration rate (GFR), urinary excretion of P and protein, renal morphologic changes, and renal tissue concentrations of calcium, P, and magnesium. Group-A dogs developed statistically significant differences from group-B dogs in several blood biochemical values (PCV and total solids, calcium, P, potassium, sodium, chloride, total CO2 (TCO2), anion gap, and parathyroid hormone concentrations) and in urinary P excretion. Mean (+/- SEM) GFR values in group-A and group-B dogs were nearly identical when diets were initiated (group A = 0.73 +/- 0.05 ml/min/kg of body weight; group B = 0.72 +/- 0.08 ml/min/kg), but significantly (P = 0.0346) lower GFR developed in group-B than in group-A dogs over time. At 24 months, GFR in survivors was 0.83 +/- 0.08 and 0.63 +/- 0.15 ml/min/kg for dogs of groups A and B, respectively. Other measurements favored the hypothesis that P/calcium restriction was beneficial, but values failed to reach statistical significance. Survival was greater at 24 months in group-A than in group-B (7 vs 5) dogs, and renal tissue concentrations of calcium and P were higher in group-B than in group-A dogs. Differences were not detected between groups in urinary excretion of protein and in the type or severity of renal lesions.(ABSTRACT TRUNCATED AT 250 WORDS)     

Exogenous creatinine clearance as a measure of glomerular filtration rate in dogs with reduced renal mass

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 less than 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.     

Quantitative urinalysis in healthy Beagle puppies from 9 to 27 weeks of age

To evaluate indices of renal function in healthy, growing Beagle puppies from 9 to 27 weeks of age and to determine whether indices change with age during this period. Animals-6 healthy Beagle puppies. PROCEDURE: Urine collections were performed at 2-week intervals in puppies 9 to 27 weeks old. Daily excretion of urinary creatinine, protein, sodium, potassium, chloride, phosphorus, and calcium were determined, as were quantitative urinalyses including endogenous creatinine clearance, urine protein-to-creatinine ratios (UPr/C), and fractional clearances of sodium (FNa), potassium (FK), chloride (FCI), calcium (FCa), and phosphorus (FP). RESULTS: Significant differences among age groups were detected for endogenous creatinine clearance, and daily urinary protein, potassium, calcium, and phosphorus excretion. Significant differences also existed among age groups for UPr/C, FNa, FK, FCI and FP. Age-related effects fit a linear regression model for FNa, UPr/C, daily phosphorus excretion, and daily protein excretion. Quadratic regression models were judged most appropriate for endogenous creatinine clearance, FK, daily chloride excretion, and daily potassium excretion. Endogenous creatinine clearance measurements higher than adult reference ranges were observed from 9 to 21 weeks of age. The FNa, FK, FCI, FCa, and FP were slightly higher than those reported for adult dogs. CONCLUSIONS AND CLINICAL RELEVANCE: Selected results of quantitative urinalyses in healthy 9- to 27-week-old Beagle puppies differ with age and differ from those measured in adult dogs. Diagnostic measurements performed in puppies of this age range should be compared with age-matched results when possible.     

Quantitative urinalysis in kittens from four to thirty weeks after birth.

To evaluate renal function and obtain reference values for measurements of urinary excretion of various substances, quantitative urinalysis was performed in healthy, growing kittens from 4 to 30 weeks after birth. Endogenous creatinine clearance, 24-hour urine protein excretion, and urine protein-to-creatinine ratio were determined. Additionally, fractional excretion to creatinine clearance was calculated for calcium, inorganic phosphorus, sodium, potassium, and chloride. Mean +/- SD endogenous creatinine clearance values (range, 3.80 +/- 0.48 to 4.74 +/- 0.61 ml/min/kg) were significantly (P less than 0.0001) higher in kittens 9 to 19 weeks old, compared with younger (range, 1.39 +/- 0.85 to 3.59 +/- 0.86 ml/min/kg) and older kittens (range, 2.69 +/- 0.40 to 3.46 +/- 0.37 ml/min/kg). Mean values for all kittens for 24-hour urine protein excretion (range, 2.54 +/- 1.81 mg/kg at 4 weeks to 11.39 +/- 7.61 mg/kg at 14 weeks) and for urine protein-to-creatinine ratio (range, 0.14 +/- 0.03 to 0.34 +/- 0.18) varied from week to week of age. The urine protein-to-creatinine ratio in kittens greater than or equal to 9 weeks old correlated well (R2 = 0.861) with 24-hour urine protein excretion. Urinary fractional excretion of calcium, inorganic phosphorus, sodium, potassium, and chloride in kittens varied among age groups, being significantly (P less than 0.01) different for potassium and calcium in young kittens (4 to 6 weeks) and older kittens (greater than or equal to 7 weeks).     

Effects of dietary protein and oathull fiber on nitrogen excretion patterns and postprandial plasma urea profiles in grower pigs

The objectives of this study were: 1) to determine if dietary protein reduction or oathull fiber inclusion would reduce urinary N excretion in grower pigs, 2) to determine if plasma urea could predict urinary N excretion among diets differing in protein and fiber content with an expected range in N excretion patterns, and 3) to determine the postprandial time point to sample blood for the best prediction. Three dietary protein concentrations (high, 19.7; medium, 16.9; low, 13.8%) and two fiber levels (high, 5.0; low, 3.6% crude fiber) were tested in a 3 x 2 factorial arrangement. Diets (wheat, barley, soybean meal; oathulls as fiber source) were formulated to 3.25 Mcal of digestible energy (DE)/kg and 2.2 g of digestible lysine/Mcal DE for low- and medium-protein diets, and 2.4 g/Mcal of DE for high-protein diets, and supplemented with lysine, methionine, tryptophan, threonine, isoleucine, or valine to meet an ideal amino acid profile. Pigs (32 +/- 3.4 kg; n = 42) were housed in metabolism crates for 19 d. On d 10 or 11, catheters were installed by cranial vena cava venipuncture. Daily feeding allowance was adjusted to 3x maintenance (3 x 110 kcal DE/kg body weight(0.75)), and was fed in two equal meals. Feces and urine were collected from d 15 to 19. Five blood samples were collected in 2-h intervals on d 16 and 19. Fecal, urinary, and total N excretion was reduced linearly with a reduction of dietary protein (P < 0.001); the reduction was greater for urinary (48%) and total N excretion (40%) than for fecal N excretion (23%). Similarly, the ratio of urinary to fecal N was reduced linearly with a reduction of dietary protein (P < 0.001). Retention of N (g/d) was reduced linearly, but N retention as a percentage of N intake was increased linearly with a reduction of dietary protein (P < 0.001). The addition of oathulls did not affect N excretion patterns and plasma urea (P > 0.10). Dietary treatments did not affect average daily gain or feed efficiency (P > 0.10). A dietary protein x time interaction affected plasma urea (P < 0.001). For medium- and high-protein diets, plasma urea increased postprandially, peaking 4 h after feeding, and then decreased toward preprandial levels (P < 0.05). Plasma urea did not alter postprandially for the low-protein diet (P > 0.10). Urinary N excretion (g/d) was predicted by 3.03 + 2.14 x plasma urea concentration (mmol/L) at 4 h after feeding (R2 = 0.66). Plasma urea concentration is indicative of daily urinary N excretion and reduction of dietary protein is effective to reduce total and urinary N excretion.     

Effect of collection time and exercise restriction on the prediction of urine protein excretion, using urine protein/creatinine ratio in dogs

Nonproteinuric and proteinuric dogs were studied to determine whether the urine protein/creatinine ratio from a 24-hour urine sample could be used to predict urine protein excretion. Urine protein/creatinine ratios estimated from urine produced during daylight hours and from that produced during nighttime hours were compared to determine whether time of sample collection influenced the prediction of the urine protein excretion value. Urine protein/creatinine ratios in urine from male dogs were compared with those from female dogs to determine whether sex had an influence on the value. Hospitalized and nonhospitalized dogs were used to determine the effect of exercise restriction. The urine protein/creatinine ratio varied significantly between healthy and proteinuric dogs (P = 0.0001). It was not influenced by collection period or sex. Animals not confined to hospital cages had a significantly lower urine protein/creatinine ratio than did hospitalized animals confined to a cage (P = 0.003).     

Influence of dietary protein content and source on colonic fermentative activity in dogs differing in body size and digestive tolerance

Low-consistency, high-moisture feces have been observed in large dogs (Canis lupus familiaris), compared with small dogs, and particularly in sensitive breeds (e.g., German Shepherd dogs). The aim of this work was to determine if greater colonic protein fermentation is responsible for poorer fecal quality in large sensitive dogs. Twenty-seven bitches were allotted to 4 groups based on size and digestive sensitivity: small, medium, large tolerant, and large sensitive. Five experimental diets varying in protein source [highly digestible wheat gluten (WG) vs. medium digestible poultry meal (PM), and protein concentration from 21.4 to 21.6 (LP) to 38.2 to 39.2% CP (HP)] were tested. Diets were fed for 14 d and followed by a 12-d transition period. Digestive fermentation by-products were investigated in fresh stools [ammonia, phenol, indole, and short chain fatty acids including acetate, propionate, and butyrate (C2 to C4 SCFA), branched-chain fatty acids (BCFA), and valerate] and in urine (phenol and indole). Bacterial populations in feces were identified. The PM diets resulted in greater fecal concentrations of ammonia, BCFA, valerate, indole, and C2 to C4 SCFA than WG diets (P = 0.002, P < 0.001, P = 0.039, P = 0.003, and P = 0.012, respectively). Greater concentrations of ammonia, BCFA, and valerate were found in the feces of dogs fed HP compared with LP diets (P < 0.001, P < 0.001, and P = 0.012, respectively). The concentrations of ammonia, valerate, phenol, and indole in feces of large sensitive dogs were greater (P < 0.001, P < 0.001, P = 0.002, and P = 0.019, respectively) compared with the other groups. The Enterococcus populations were greater in feces of dogs fed with PMHP rather than WGLP diets (P = 0.006). Urinary phenol and indole excretion was greater when dogs were fed PM than WG diets (P < 0.001 and P = 0.038, respectively) and HP than LP diets (P = 0.001 and P = 0.087, respectively). Large sensitive dogs were prone to excrete a greater quantity of phenol in urine (P < 0.001). A diet formulated with highly digestible protein, such as WG, led to reduced concentrations of protein-based fermentation products in feces together with improved fecal quality in dogs, especially in large sensitive ones. Poor fecal quality in large sensitive dogs could be partly related to the pattern of protein fermentation in the hindgut.     

Use of protein-to-creatinine ratio in a single urine specimen for quantitative estimation of canine proteinuria

The daily excretion of urinary protein was evaluated in 8 conditioned research dogs and in 10 hospitalized, proteinuric dogs, using 24-hour urine collections. Concurrent with each 24-hour urine collection, a 5- to 10-ml urine specimen was obtained during midday. The ratio of urine protein to urine creatinine concentration was determined from the single urine specimen for each dog. Linear regression analysis was used to calculate the correlation between that ratio and the 24-hour urinary protein loss (mg/kg of body weight). The coefficient of determination was significant (r2 = 0.95, P less than 0.0001). Determination of the protein-to-creatinine ratio in a single urine specimen was found to be a sensitive, rapid, and dependable diagnostic technique for detection and quantitative estimation of proteinuria.     

Initial evaluation of canine urinary cystatin C as a marker of renal tubular function

Objectives : To evaluate the performance of a particle‐enhanced turbidimetric assay for measuring canine urinary cystatin C and to investigate if the urinary cystatin C to creatinine ratio is higher in dogs with renal disease than in non‐renal disease dogs. Methods : Urinary cystatin C was measured by particle‐enhanced turbidimetric assay using an avian antihuman cystatin C antibody and the performance of this assay was evaluated. Clinical relevance was tested in 46 dogs that were divided into three groups: healthy dogs (n=14), non‐renal disease dogs (n=17) and dogs with renal disease (n=15). Results : The assay was linear (R2=0·99) and precise (mean intra‐ and inter‐assay coefficients of variation were 2·3 and 2·9%, respectively). The recovery was 111·5% and the limit of blank was 0·02 mg/L. Urinary cystatin C and urinary cystatin C to creatinine ratio differed significantly (P<0·001) between the three cohorts of dogs. Clinical Significance : Measurement of cystatin C by particle‐enhanced turbidimetric assay performed with high precision and linearity. This assay can be processed on automated clinical chemistry analysers making it widely available to commercial laboratories. Urinary cystatin C to creatinine ratio can differentiate dogs with renal disease from dogs without renal disease. These preliminary results suggest that urinary cystatin C to creatinine ratio is a promising marker for evaluating renal tubular function.     

Urinary gamma-glutamyl transpeptidase activity in dogs with gentamicin-induced nephrotoxicity

Serum creatinine concentrations, 24-hour endogenous creatinine clearance, and 24-hour urinary gamma-glutamyl transpeptidase (UGGT) activity were measured daily in 6 dogs given nephrotoxic dosages of gentamicin (10 mg/kg of body weight) every 8 hours for 10 days. Mean UGGT activity was significantly increased by day 5 (P less than 0.05) and preceded significant increases in serum creatinine values (greater than 2.0 mg/dl) observed on day 9. Endogenous creatinine clearance remained within normal limits (2.98 +/- 0.96 ml/min/kg) until day 8. Urinalyses performed 8 days after initiation of gentamicin treatment indicated renal tubular damage (granular casts) in 1 of the 6 dogs, and glucosuria in 3 of the 6 dogs. Measurement of UGGT activity was a more sensitive and reliable method of assessing acute renal tubular damage induced by gentamicin than were serum creatinine concentrations or 24-hour endogenous creatinine clearance.     

Evaluation of albuminuria and its relationship with blood pressure in dogs with chronic kidney disease

Background: Microalbuminuria and hypertension have long been associated with a guarded prognosis in human patients with a variety of diseases. In veterinary medicine, tests for microalbuminuria have been used for detecting early kidney damage, but there is little information regarding its association with high blood pressure in dogs with chronic kidney disease (CKD). Objective: The objective of this study was to evaluate albuminuria and its association with arterial hypertension in dogs with CKD. Methods: Urinary albumin:creatinine (UAC) ratio, urinary protein:creatinine (UPC) ratio, and systolic blood pressure were determined in 39 clinically healthy dogs and 40 dogs with CKD. Results: UAC in dogs with CKD (range, 0.002–7.99; median, 0.38) was statistically different from that of control dogs (range, 0.0005–0.01; median, 0.002). Microalbuminuria (UAC 0.03–0.3) and macroalbuminuria (UAC>0.3) were detected in 32.5% and 50% of dogs with CKD, respectively. Sixty percent (24/40) of dogs with CKD had systolic pressure ≥180 mmHg; in these dogs, UAC ratio (range, 0.006–7.99; median, 1.72) was significantly higher than in dogs with CKD and systolic pressure<180 mmHg (range, 0.002–4.83; median, 0.10). Of hypertensive dogs with CKD, those with UPC>1.0 usually had macroalbuminuria, those with UPC 0.5–1.0 usually had microalbuminuria, and those with UPC<0.5 usually lacked albuminuria. Conclusions: UAC ratio was higher in hypertensive than in normotensive dogs with CKD. Tests designed to detect microalbuminuria may be useful for hypertensive dogs with CKD and a UPC≤1.0 to detect the onset and magnitude of albuminuria. Once macroalbuminuria is overt, the UPC ratio itself can be used for the same purpose.     

Effects of Glucocorticoid Therapy on Urine Protein-to-Creatinine Ratios and Renal Morphology in Dogs

Glomerulonephritis has been associated with exogenous glucocorticoid administration and spontaneous hyperadrenocorticism in the dog. The purpose of this study was to determine the effects of long-term glucocorticoid therapy on urine protein:creatinine ratios (UP/Cs) and renal morphology. Nine young-adult male dogs were determined to be healthy and have normal renal function as assessed by physical examination, CBC, serum biochemistry analysis, Knott's test for Dirofilaria immitis , urinaly-sis, urine culture, urine protein electrophoresis, endogenous creatinine clearance, 24-hour urinary protein excretion, and UP/C. Prednisone was administered to each dog at a dosage of 2.2 mg/kg PO bid for 42 days. Urinalysis and UP/C were performed on days 0, 7, 14, 21, 28, and 42 of treatment. Mean UP/C on day 0 was 0.29 ± 0.10. Mean UP/C increased progressively to a maximum of 1.27 ± 1.02 on day 28. Mean UP/C on day 42 decreased slightly (0.92 ± 0.56) but remained significantly increased above baseline.
The most consistent renal light microscopic finding on necropsy examination was generalized hypercellular glomerular tufts, suggestive of mesangial cell proliferation. Four dogs also had occasional adhesions of glomerular tufts to Bowman's capsule, accompanied by thickening of the capsule. Direct immunofluorescence for immunoglobulin deposition was negative in all dogs. Electron microscopy, evaluated in 7 dogs, was characterized by occasional mild segmental thickening of basement membranes, fusion of visceral cell foot processes, and glomerular adhesions. The results of this study indicate that long-term administration of glucocorticoids results in significant proteinuria and glomerular changes in the dog.     

Effects of dietary protein and fermentable fiber on nitrogen excretion patterns and plasma urea in grower pigs

Effects of dietary protein concentration (high, 18.5; low, 15.7%) and fermentable fiber (control; soyhulls, SH; and sugar beet pulp, SBP) on N excretion patterns and plasma urea were tested in a 2 x 3 factorial arrangement. The objectives were: 1) to determine if reduced dietary protein together with fermentable fiber would reduce urinary N excretion further than a single diet manipulation, 2) to determine if effects of diet manipulations were similar between pigs with restricted and free access of feed, and 3) to further develop predictions of urinary N excretion using plasma urea. Diets were formulated to 3.30 Mcal digestible energy (DE)/kg and 2.4 g of digestible lysine per Mcal DE, and supplemented with lysine, methionine, tryptophan, threonine, isoleucine, leucine, or valine to ensure meeting an ideal AA profile. Pigs (30.5 +/- 3 kg; n = 36) were housed in metabolism crates with restricted access to feed (3 x 110 kcal DE/kg BW(0.75)) from d 1 to 18, and free access from d 19 to 26. Feces and urine were collected from d 15 to 18 and d 23 to 26, and blood was sampled on d 17 and 25. With restricted access to feed, urinary N was reduced 28% and N retention was reduced 12% for the low- compared to high-protein diet (P < 0.01; as g/d). Fecal N was increased 4% units for SH and 6.5% units for SBP (P < 0.01; as % of N intake) and urinary N was reduced 5% units for SH (P < 0.10) and 9% units for SBP (P < 0.05) compared to the control. With free access to feed, urinary N was reduced 27% (P < 0.05; as g/d) and N retention was reduced 7% (P < 0.10) for the low- compared to high-protein diet. Fecal N was increased 5% units for SH and 9% units for SBP (P < 0.001; as % of N intake), and urinary N was reduced 9% units for SH and 10% units for SBP (P < 0.01) compared to the control. For either restricted or free access to feed, fermentable fiber did not affect N retention (P > 0.10). A protein x fiber interaction was not observed for urinary N excretion (P > 0.10), indicating that reducing dietary protein and including fermentable fiber reduced urinary N excretion in an additive manner. Daily urinary N excretion was related positively and linearly with plasma urea in pigs with free access to feed (R2 = 0.71; at 0800). In summary, reduction of dietary protein reduced urine N excretion, and fermentable fiber shifted N excretion from urine to feces. Effects of dietary protein and fermentable fiber on reducing urinary N excretion are additive.     

Clinical availability of urinary N-acetyl-beta-D-glucosaminidase index in dogs with urinary diseases

Urinary excretion of N-acetyl-beta-D-glucosaminidase (NAG) was examined in healthy dogs and dogs with urinary diseases, and its clinical usefulness as an indicator of urinary diseases was discussed. Twenty-eight healthy dogs and 20 dogs with urinary diseases were used. Urinary NAG activity was measured using p-nitrophenyl N-acetyl-beta-D-glucosaminide as substrate, and expressed as units per gram of urinary creatinine (NAG index). Urinary NAG index in urine of healthy dogs was 3.2+/-2.4 U/g, and NAG index in the dogs with chronic renal failure or lower urinary tract infection accompanied by pyelonephritis was higher than that in healthy dogs. However, the dogs with lower urinary tract infection without pyelonephritis showed normal values of NAG index. Some dogs with diabetic mellitus showed elevated values of NAG index when control of blood sugar was not successful. Increase of NAG index was observed in some dogs with pyometra before increases of BUN and serum creatinine concentration. Therefore, NAG index in urine seems to be a good indicator for urinary diseases in dogs.