OBJECTIVE To determine whether urine protein-to-creatinine ratio (UP:C) > or = 1.0 at initial diagnosis of chronic renal failure (CRF) is associated with greater risk of development of uremic crises, death, and progression of renal failure in dogs. DESIGN Prospective cohort study. ANIMALS 45 dogs with CRF PROCEDURE: Dogs were prospectively assigned to 2 groups on the basis of initial UP:C < 1.0 or 2 > or = 1.0. The association between magnitude of proteinuria and development of uremic crises and death was determined before and after dogs with initial UP:C > or =1.0 were assigned to 3 subgroups and compared with dogs with initial UP:C < 1.0. Changes in reciprocal serum creatinine concentration were used to estimate decrease in renal function. RESULTS Initially, dogs had similar clinical characteristics with the exception of systolic blood pressure and UP:C. Relative risks of development of uremic crises and death were approximately 3 times higher in dogs with UP:C > or =1.0, compared with dogs with UP:C < 1.0. Relative risk of adverse outcome was approximately 1.5 times higher for every 1-unit increment in UP:C. The decrease in renal function was of greater magnitude in dogs with UP:C > or =1.0, compared with dogs with UP:C < 1.0. CONCLUSIONS AND CLINICAL RELEVANCE Initial UP:C > or =1.0 in dogs with CRF was associated with greater risk of development of uremic crises and death, compared with dogs with UP:C < 1.0. Initial determinations of UP:C in dogs with naturally occurring CRF may be of value in refining prognoses.

OBJECTIVE To determine whether a diet used for dogs with renal failure (renal food [RF]) was superior to an adult maintenance food (MF) in minimizing uremic crises and mortality rate in dogs with spontaneous chronic renal failure. DESIGN Double-masked, randomized, controlled clinical trial. ANIMALS 38 dogs with spontaneous chronic renal failure. PROCEDURE Dogs were randomly assigned to a group fed adult MF or a group fed RF and evaluated for up to 24 months. The 2 groups were of similar clinical, biochemical, and hematologic status. The effects of diets on uremic crises and mortality rate were compared. Changes in renal function were evaluated by use of serial evaluation of serum creatinine concentrations and reciprocal of serum creatinine concentrations. RESULTS Compared with the MF, the RF had a beneficial effect regarding uremic crises and mortality rate in dogs with mild and moderate renal failure. Dogs fed the RF had a slower decline in renal function, compared with dogs fed the MF. CONCLUSIONS AND CLINICAL RELEVANCE Dietary modifications are beneficial in minimizing extrarenal manifestations of uremia and mortality rate in dogs with mild and moderate spontaneous chronic renal failure. Results are consistent with the hypothesis that delay in development of uremic crises and associated mortality rate in dogs fed RF was associated, at least in part, with reduction in rate of progression of renal failure.

Objective-To determine whether hydrochlorothiazide (HCTZ) reduces urinary calcium excretion in dogs with calcium oxalate urolithiasis.Design-Original study.Animals-8 dogs with calcium oxalate urolithiasis.Procedure-4 treatment protocols were evaluated in each dog ia low calcium, low protein diet designed to prevent calcium oxalate urolith formation with and without administration of HCTZ [2 mg/kg (0.9 mg/lb) of body weight, PO, q 12 h] and a maintenance diet with higher quantities of protein and calcium with and without administration of HCTZ). At the end of each 2-week treatment period, 24-hour urine samples were collected. Blood samples were collected during the midpoint of each urine collection period. Analysis of variance was performed to evaluate the effects of HCTZ and diet on urine and serum analytes.Results-Hydrochlorothiazide significantly decreased urine calcium and potassium concentration and excretion. Hydrochlorothiazide also significantly decreased serum potassium concentration. Compared with the maintenance diet, the urolith prevention diet significantly decreased urine calcium and oxalic acid concentration and excretion. Dogs consuming the urolith prevention diet had significantly lower serum concentrations of albumin and urea nitrogen.Conclusions and Clinical Relevance-Administration of HCTZ decreased urine calcium excretion in dogs with a history of calcium oxalate urolith formation. The greatest reduction in urine calcium concentration and excretion was achieved when dogs received HCTZ and the urolith prevention diet. Results of this study suggest that the hypocalciuric effect of HCTZ will minimize recurrence of calcium oxalate urolith formation in dogs; however, long-term controlled clinical trials are needed to confirm the safety and effectiveness of HCTZ.

OBJECTIVE:To test the hypothesis that breed, age, sex, body condition, and environment are risk factors for development of calcium oxalate uroliths in dogs.DESIGN:Case-control study.ANIMALS:1,074 dogs that formed calcium oxalate uroliths and 1,724 control dogs that did not have uroliths.PROCEDURE:A validated multiple-choice questionnaire was designed to collect information from veterinarians and owners within 1 year of the date of urolith detection concerning signalment and environment of the dogs. Univariate and multivariate analyses were performed to calculate odds ratios to assess whether breed, age, sex, body condition, and environment were risk factors for calcium oxalate urolith formation.RESULTS:Middle-aged (8- to 12-year-old) castrated male dogs had increased risk for formation of calcium oxalate uroliths. Urolith formation was also associated with increasing age. Dogs of certain breeds, including Miniature and Standard Schnauzer, Lhasa Apso, Yorkshire Terrier, Bichon Frise, Shih Tzu, and Miniature and Toy Poodle, had increased risk for developing calcium oxalate uroliths. Overweight dogs also had increased risk.CONCLUSIONS AND CLINICAL RELEVANCE:Knowledge of patient and environmental risk factors for development of calcium oxalate uroliths may facilitate development of surveillance strategies that result in earlier detection of this disease. Modification of environmental factors and body weight may minimize calcium oxalate urolith formation and recurrence.

Formation of uroliths is not a disease but rather a complication of several disorders. Some disorders can be identified and corrected (e.g., infection-induced struvite urolith formation), and some can be identified but not corrected (e.g., hyperuricosuria occurring in Dalmatians that form ammonium urate uroliths), although for others, the underlying etiopathogenesis is not known (e.g., calcium oxalate urolith formation in Miniature Schnauzers). A common denominator of these disorders is that from time to time, they can create oversaturation of urine with one or more crystal precursors, resulting in formation of crystals. To develop rational and effective approaches to treatment, abnormalities that promote urolith formation must be identified with the goal of eliminating or modifying them. It is therefore important to understand several basic concepts associated with urolithiasis.

The case study presented here illustrates the diagnosis and management of calcium oxalate urolithiasis in a Bichon Frise, a breed at increased risk for this type of stone. If the Bichon Frise had persistent hypercalcemia, we would have evaluated serum concentrations of ionized calcium, parathyroid hormone, and vitamin D to identify an underlying cause. Because his urine was alkaline, additional potassium citrate was not provided. Likewise, as a fortified diet was fed to him, vitamin B6 therapy was not considered. This case study illustrates the benefits of radiographic evaluation immediately following surgery and during follow-up examinations. If we had postponed radiographs until the patient developed clinical signs, additional surgical procedures may have been required.

Two types of canine struvite uroliths have been recognized: infection-induced struvite is the most common type; sterile struvite is uncommonly recognized. Infection-induced struvite is most commonly associated with urease-producing staphylococcal UTI. For dogs that qualify, medical dissolution is an effective method of treatment. Medical dissolution protocols encompass: (1) eradication or control of UTI; (2) use of calculolytic diets; and (3) administration of urease inhibitors to patients with persistent UTI caused by urease-producing microbes.

The kidneys eliminate the acid produced each day by metabolism and diet. Consequently, urinary pH is influenced by diet. The urinary pH of cats consuming a "habitual" diet of small mammal carcasses is between 6.2 and 6.4. Although the only authoritative way to determine the effect of diet on urinary pH is to do a feeding trial, there is no universally accepted protocol for measuring urinary pH.

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.

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 of all diets was associated with production of 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 of diets containing approximately 10.5% protein (dry weight) and 70% moisture in protocols designed for dissolution and prevention of urate uroliths may be beneficial. The source of dietary protein in canned formulated diets does not appear to significantly influence the saturation of urine with uric acid, sodium urate, or ammonium urate.

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 product 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 24-hour urinary excretions of ammonia and phosphorus were observed when dogs consumed 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.

The correlation between 24-hour urinary excretion of N-acetyl-beta-D-glucosaminidase (NAG) and gamma-glutamyl transferase (GGT) with urine NAG and GGT/creatinine ratios was assessed in dogs with gentamicin-induced nephrotoxicosis. Eighteen 6-month-old male Beagles with normal renal function were randomly divided into 3 groups of 6. Each group was fed a different concentration of protein (high protein, 27.3%; medium protein, 13.7%; and low protein, 9.4%) for 21 days. After dietary conditioning, gentamicin was administered at a dose of 10 mg/kg IM tid for 8 days and each group was continued on its respective diet. Endogenous creatinine clearance and 24-hour urinary excretion of NAG and GGT were determined after dietary conditioning (day 0) and on days 2, 4, 6, and 8 of gentamicin administration. In addition, urine NAG and GGT/creatinine ratios (IU/L divided by mg/dL) were determined from catheterized spot urine samples obtained between 7 and 10 AM on the same days. The correlation between 24-hour urinary enzyme excretion and urine enzyme/creatinine ratio in the spot urine samples was evaluated by simple linear regression analysis. Spot sample urine enzyme/creatinine ratios were significantly correlated with 24-hour urinary enzyme excretion through day 4 for dogs on low dietary protein, through day 6 for those on medium protein, and through day 8 for those on high dietary protein. Mean +/- SD baseline values for urine NAG/creatinine ratio and 24-hour urinary NAG excretion were 0.06 +/- 0.04 and 0.19 +/- 0.14 IU/kg/24 hr, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Eighteen, six-month-old male Beagles with normal renal function were randomly divided into three groups of 6. Each group was fed a diet that was similar except for protein content (high = 26%, medium = 13% and low = 9%, all on an as fed basis) throughout the experimental period. After a 21 day dietary protein conditioning period (including a terminal 2 day testing period), gentamicin was administered at a dosage of 10 mg/kg q. 8 h for 8 days. The first dose on days 1 and 7 was administered i.v. and all others were given i.m. Pharmacokinetic parameters were determined using blood samples collected over an 8 h period following the i.v. dose on day 1. The elimination rate constant was calculated on days 1 and 7. The data best fit a two-compartment open model for all dogs on day 1. The volume of distribution was higher and the clearance greater in the high protein group compared to the other two groups. No difference was found in the rate of elimination between days 1 and 7 for the high protein group; however, in the medium and low protein groups the rate of elimination decreased over the 7 days of treatment. Therefore, high dietary protein prior to and during gent-amicin administration induced faster gentamicin clearance and a larger volume of distribution and preserved the ability to eliminate gentamicin in dogs with normal renal function.

Eighteen 6-month-old male Beagles with normal renal function were allotted at random to 3 groups of 6 dogs each. For 21 days, each group was fed a diet that was similar except for protein content (high protein, 27.3%; medium protein, 13.7%; and low protein, 9.4%). After the conditioning period, gentamicin was administered at a dosage of 10 mg/kg of body weight, IM, every 8 hours for 8 days, and the respective diet was continued. Clearance of endogenous creatinine, 24-hour urinary excretion of protein and enzymes (gamma-glutamyltransferase, and N-acetyl-beta-D-glucosaminidase, and fractional clearance of sodium and potassium (%) were determined before and after dietary protein conditioning and on days 2, 4, 6, and 8 of gentamicin administration. Additionally, trough serum gentamicin concentration was determined on days 2, 4, 6, and 8 of gentamicin administration. At the end of the study, all dogs were euthanatized; renal histologic features were graded, using a continuous ranking scale, and renal cortical gentamicin concentrations were measured. Data were ranked and analyzed, using a nonparametric equivalent of a two-way ANOVA; P < 0.05 was considered significant. After the dietary conditioning period (prior to gentamicin), dogs fed the high-protein diet had higher endogenous creatinine clearance and urinary excretion of protein, compared with dogs fed the low-protein diet. Differences existed among groups after 8 days of gentamicin administration.(ABSTRACT TRUNCATED AT 250 WORDS)

Consideration of species differences in neonatal renal function may allow the clinician to individualize fluid and electrolyte diagnostics and therapeutics for specific species. Postparturient renal function maturation differs widely among species and may have important effects on neonatal responses to dehydration or electrolyte depletion as well as handling of fluid replacement formulas and therapeutic drugs. In most species, it is important to recognize the propensity for neonatal water and solute loss as well as the rapidity with which clinical signs of imbalance may become apparent.

To evaluate adequacy of biopsy specimens obtained and safety to the patient, the standard keyhole biopsy technique (using digital immobilization of the right kidney and placement of the biopsy needle up to the capsule before obtaining a tissue sample) was compared with 9 technical modifications. Adequacy was judged by the number of intact glomeruli observed in the specimen. Detection of transected blood vessels and renal pelvis was presumed to have predictive value for postbiopsy complications of hemorrhage and hydronephrosis. Needle biopsy specimens were also obtained from left and right kidneys by use of laparoscopic visualization and were compared with those obtained by use of the standard keyhole technique. Although the standard keyhole technique yielded the highest percentage of adequate biopsy specimens, there was no statistical difference between specimens obtained by this technique and those obtained by the modified technique or by laparoscope-guided biopsy. Also, significant difference in percentage of biopsy specimens with renal pelvis was not found between specimens obtained by the standard and modified techniques. For each technique, the biopsy core length was measured and the mean value was calculated. In this study, core length did not correlate with adequacy of the biopsy specimen.