Evaluation of urinary enzymes in dogs with early renal disorder

N-acetyl-β-D-glucosaminidase in clinically healthy German Shepherd dogs and dogs with early stages of chronic kidney disease

Urinary N-acetyl-β-D-glucosaminidase (NAG) activity is associated with kidney disease. In our study, we focused on evaluating the ratio of NAG to the urinary creatinine concentration (NAG/Cr) in the German Shepherd breed. Sixty-two healthy dogs and thirteen dogs with chronic kidney disease (CKD) were examined. The healthy dogs were divided into groups based on their sex and age (puppies and adolescent dogs under 2 years, adult dogs from 2 to 6 years and seniors over 6 years), while the dogs with CKD were divided based on the disease stage (CKD stage 1 and 2). No significant difference was detected between the males and females. Regarding the age dependence, significantly higher values were found in dogs older than 6 years (P = 0.020 3) compared to dogs aged 2-6 years. When comparing the healthy dogs to the dogs with CKD, the lowest NAG/Cr ratio was observed in the dogs with CKD stage 2. The reference interval for NAG/Cr in the German Shepherd was established in the range of 0.78-7.86 U/gCr. We observed no correlations with the commonly used markers of kidney disease such as creatinine, urea, or symmetrical dimethylarginine. Nevertheless, we encourage the further investigation of NAG in relation to CKD, taking the breed, sex and age of the patients into account.

Measurement of Selected Renal Biochemical Parameters in Healthy Adult Donkeys Considering the Influence of Gender, Age and Blood Freezing

The reference values of the serum and urine biochemical parameters have not been well-studied in donkeys. This study aimed to assess the normal values of the selected renal biomarkers, such as: serum creatinine, blood urea nitrogen (BUN), albumin, total protein (TP), electrolytes and symmetric dimethylarginine (SDMA), urine protein concentration (UPC), urine protein/creatinine ratio (UPCR), the urine gamma-glutamyl transferase (GGTP)-to-creatinine ratio, serum creatinine-to-urine creatinine ratio (sCr/uCr), serum BUN-to-serum creatinine ratio (sBUN/sCr) and UPC-to-TP ratio, as well as the fractional electrolyte excretion of sodium (FENa) and potassium (FEK) in donkeys. The effects of age, gender and deep freezing of the serum material were investigated. Sixty-five healthy adult donkeys were involved in this study. The results showed higher BUN and TP values and lower albumin, UPCR, FENa and FEK levels in donkeys when compared to the reference values in horses. A significant gender relationship for creatinine and BUN was found. Age influenced the values of albumin, TP, potassium and chlorine. Potassium, sodium and SDMA did not show significant concentration changes after freezing. The study results demonstrated that horse reference range values for some parameters cannot be applied to donkey samples. Only a few of the serum parameters were not affected by freezing, and this should be taken into account when storing biological materials.

Electrophoretic analysis (sds-page) of canine urinary proteins according to the stage of chronic kidney disease

ABSTRACT Glomerular proteinuria is characterized by the loss of high-molecular-weight proteins (HMWPs), while tubulointerstitial proteinuria is characterized by the loss of low-molecular-weight proteins (LMWPs). The objective was to assess the molecular weight of urinary proteins (MWUP) in dogs with naturally acquired CKD and determine the proportion of HMWPs and LMWPs according to CKD stage. Twenty-eight dogs with CKD were recruited and divided into 4 groups based on serum creatinine (Cr) levels (group1: Cr<1,4, n=8; group2: 1,4<Cr<2,0, n=6; group3: 2,1<Cr<5, n=9; group4: Cr>5,0, n=5). The control group consisted of 5 healthy dogs. The MWUP was determined by SDS-PAGE. The urinary protein-to-creatinine ratio (UP/C) was used to quantitatively assess proteinuria. The electrophoresis pattern revealed a proportionally greater loss of HMWPthan of LMWP in all groups with CKD and an increased loss of LMWP in group 4 (P<0.05). These results suggest a predominance of glomerular injuries throughout all stages of CKD in these dogs and an increase in tubulointerstitial injury towards the end-stage of the disease. The results of the present study support the recommendation of SDS-PAGE as an effective technique for the qualitative assessment of proteinuria, as well as a method for assessing the severity and location of renal injury.

Equine urinary N-acetyl-β-D-glucosaminidase assay validation and correlation with other markers of kidney injury

Detection of equine acute kidney injury (AKI) is hindered by limited markers of early renal damage in horses. N-acetyl-β-D-glucosaminidase (NAG), a lysosomal enzyme in renal tubular epithelium released into urine during tubular insult, has shown promise for early identification of AKI in humans and other species. We validated an assay for NAG in equine urine and measured urinary NAG in 7 azotemic and 7 non-azotemic client-owned adult horses. The enzymatic NAG assay was validated using within- and between-run coefficients of variation (CVs), recovery following standard addition, and linearity of dilution. Intra- and inter-run CVs (21% and 3.2%, respectively), average recovery following standard addition (99-109%), and linearity under serial dilution (R² = 0.997) were satisfactory. Urine NAG index was significantly correlated with urinary fractional excretion of sodium (FE_Na; ρ = 0.76, p < 0.001) and plasma creatinine (ρ = 0.74, p = 0.001). Median urine NAG indices were higher in azotemic horses (p = 0.006), in horses with increased urinary FE_Na (p = 0.006), and in horses with increased urine gamma-glutamyl transferase index (p = 0.032). Urine NAG can be measured in horses and shows positive correlation with 2 current renal biomarkers. Additional work is needed to establish normal equine reference intervals and characterize the increase of urine NAG index in horses in relation to tubular injury.

Use of urinary γ-glutamyl transferase (GGT) to monitor the pattern of proteinuria in dogs with leishmaniasis treated with N-methylglucamine antimoniate

The aim of this study was to assess if the coupled analysis of the urinary protein to creatinine (UPC) ratio and of the GGT/UC ratio (the ratio between urinary γ-glutamyl transferase activity and urinary creatinine) may be used in treated leishmaniotic dogs to differentiate dogs with transient impairment of tubular function from dogs with persistent tubular damage. To this aim, 40 urine from 10 proteinuric and leishmaniotic dogs that at the first visit had high GGT/UC ratio, consistent with tubular damage, were collected and analyzed before treatments and 2, 4 and 6 weeks after treatment with N-methylglucamine antimoniate and allopurinol. Compared with pre-treatment values, at the end of the study period the UPC ratio decreased only in 5/10 dogs, which, however, were still proteinuric or borderline proteinuric. Conversely, the GGT/CU ratio decreased in 8/10 dogs and in 3 of them the values at the end of the study period were below the threshold consistent with tubular proteinuria. The GGT/UC values at 6 weeks was significantly lower than before treatment. However, transient increases were frequent for both the analytes. These results indicate that in most of the dogs that remain proteinuric after treatment, likely due to the persistent glomerular damage, the GGT/UC ratio tends to normalize. This suggests that in these dogs tubular proteinuria at admission depends on functional impairment of tubular cells likely due to the overflow of proteins from damaged glomeruli. However, tubular proteinuria occasionally persists, suggesting that tubulointerstitial damages persist even in dogs responsive to treatments.

Utility of urinary alkaline phosphatase and γ-glutamyl transpeptidase in diagnosing acute kidney injury in dogs

The diagnostic utility of urinary alkaline phosphatase (uALP) and γ-glutamyl transpeptidase (uGGT) activities in naturally occurring acute kidney injury (AKI) was investigated in a heterogeneous group of dogs. The study included client-owned dogs with AKI (n = 32), chronic kidney disease (CKD, n = 13), lower urinary tract infection (LUTI, n = 15) and healthy controls (n = 24). uGGT and uALP activities were normalised to urinary creatinine (uCr) concentrations (uGGT/uCr and uALP/uCr, respectively). uALP/uCr and uGGT/uCr were positively and significantly correlated (r = 0.619, P <0.001), and differed significantly (P ≤ 0.001) among groups, as well as between AKI and LUTI or CKD groups (P < 0.05), but not between the AKI and control groups. Areas under the receiver operator characteristics (ROC) curve for uALP/uCr and uGGT/uCr as predictors of AKI were 0.75 and 0.65, respectively, with optimal cut-off points showing poor to moderate sensitivity (59% for uALP/uCr and 79% for uGGT/uCr) and specificity (59% for uALP/uCr and 75% for uGGT/uCr). Higher cut-off points, with 90% specificity, showed low sensitivity (41% for both uALP/uCr and uGGT/uCr). In conclusion, uALP/uCr is superior to uGGT/uCr as a marker of AKI, but both uGGT/uCr and uALP/uCr have unsatisfactory discriminatory power for diagnosing naturally occurring AKI in dogs and therefore cannot be recommended as sole screening tests for canine AKI. However, both may serve as ancillary, confirmatory, biomarkers for detecting AKI in dogs if appropriate cut-off points with high specificities are used.

Urinary parameters predictive and electrolyte disturbances of cisplatin-induced acute renal associated with cancer as a critical target of the chemotherapeutic agent in patients with solid tumors

Cisplatin (CP) is a remarkably effective Pt-based anticancer drug, but it also exhibits severe toxic side effects, including nephrotoxicity and ototoxicity, and CP nephrotoxicity is a major constraint for the treatment of solid tumors. This study was designed to evaluate the electrolyte and biochemical changes in dogs with acute kidney injury (acute renal failure) following administration of CP as a chemotherapeutic agent to exhibit broad efficacy in solid tumors. A total of 10 adult male dogs were selected (treated dogs = 7 and control dogs = 3). Cisplatin-treated animals were received 0.75 mg/kg via intravenous for 5 consecutive days. Urine and blood samples on days 0 (pre-dosing), 1, 2, 3, 4, 7, 10, 14, and 28 (post-dosing) were collected. For tracking the signs of toxicity with cisplatin, clinical examination was performed for 2 times a day. Serum samples were assayed urea, creatinine, sodium, chloride, potassium, calcium, phosphorus, and urine samples were used to measure creatinine. Serum creatinine levels indicating renal function (glomerular filtration rate) was 0.66 and 0.94 mg/dL in day 0, respectively, in treatment and control animals. After day 2, a significant change in creatinine was observed in treatment animals. On the end day of the study control and treatments, creatinine was measured with mean of 1.35 and 1.00 mg/dL, respectively. Electrolyte disturbances were observed after several days of cisplatin administration including changes in levels of sodium, potassium, phosphorus, calcium, and chloride. Clinical observations also identified CP toxicity. This study for the first time showed that compensation electrolyte abnormalities in dogs following administration of cisplatin is essential to prevent deaths by daily monitoring and measurement of electrolytes in patients. This may be advantageous if repetitive cycles of chemotherapy or subsequent administration of high dose chemotherapy were planned.

Biomarkers in the assessment of acute and chronic kidney diseases in the dog and cat

In both human and veterinary medicine, diagnosing and staging renal disease can be difficult. Measurement of glomerular filtration rate is considered the gold standard for assessing renal function but methods for its assessment can be technically challenging and impractical. The main parameters used to diagnose acute and chronic kidney disease include circulating creatinine and urea concentrations, and urine-specific gravity. However, these parameters can be insensitive. Therefore, there is a need for better methods to diagnose and monitor patients with renal disease. The use of renal biomarkers is increasing in human and veterinary medicine for the diagnosis and monitoring of acute and chronic kidney diseases. An ideal biomarker would identify site and severity of injury, and correlate with renal function, among other qualities. This article will review the advantages and limitations of renal biomarkers that have been used in dogs and cats, as well as some markers used in humans that may be adapted for veterinary use. In the future, measuring a combination of biomarkers will likely be a useful approach in the diagnosis of kidney disorders.

Early detection of ketoprofen-induced acute kidney injury in sheep as determined by evaluation of urinary enzyme activities

OBJECTIVE

To evaluate early indicators of renal tissue destruction and changes in urinary enzyme activities in sheep during the first hours after acute kidney injury induced by administration of an overdose of an NSAID.

ANIMALS

12 adult female sheep.

PROCEDURES

Acute kidney injury was induced in 6 sheep by administration of ketoprofen (30 mg/kg, IV) and detected by evaluation of urinary protein concentration, iohexol clearance, and results of histologic examination. Six sheep served as control animals. Blood and urine samples were collected for up to 24 hours after administration of ketoprofen. Plasma concentrations of urea, creatinine, albumin, and total protein; plasma activities of alkaline phosphatase, acid phosphatase, γ-glutamyl transpeptidase (GGT), matrix metalloproteinase (MMP)-2, and MMP-9; and urinary creatinine and protein concentrations, specific gravity, and activities of alkaline phosphatase, acid phosphatase, GGT lactate dehydrogenase, N-acetyl-β-D-glucosaminidase (NAG), MMP-2, and MMP-9 were measured. Urinary protein concentration and enzyme activities were normalized on the basis of urinary creatinine concentrations and reported as ratios.

RESULTS

Many urinary enzyme-to-creatinine ratios increased before the plasma creatinine concentration exceeded the reference value. Urine NAG, lactate dehydrogenase, and acid phosphatase activities were increased beginning at 2 hours after ketoprofen administration, and alkaline phosphatase, GGT, and MMP-2 activities were increased beginning at 4 hours after ketoprofen administration. Most peak urinary enzyme-to-creatinine ratios were detected earlier than were the highest plasma creatinine and urea concentrations.

CONCLUSIONS AND CLINICAL RELEVANCE

Urinary enzyme activities were sensitive early indicators of acute kidney injury induced by an overdose of an NSAID in sheep.

Urinary parameters predictive of cisplatin-induced acute renal injury in dogs

A 28-day study was conducted to evaluate changes in urinary cytokine/chemokine expression levels in dogs with renal injury due to administration of cisplatin. Animals (n=17) were administered cisplatin at 0.75 mg/kg/day (i.v.) for five consecutive days. Urine/serum were collected at pre-dosing, 4h post-dosing and on days 2, 3, 4, 8, 10, 14, 16, 18, 21, 23, 25, 28 and unscheduled terminations. Animals were euthanized when serum creatinine (sCr) levels measured at ≥ 1.9 mg/dL, indicating significant loss of renal function (decreased glomerular filtration rate). Relevant clinical observations included lethargy and dehydration. Pre-study sCr levels ranged from 0.6 to 0.8 mg/dL; on days 1 through 4, sCr levels ranged from 0.5 and 1.1mg/dL; and terminal sCr levels ranged from 0.6 and 6.6 mg/dL. Histologically, cisplatin-related renal changes were characterized as proximal tubule dilatation, vacuolization, degeneration, regeneration, and interstitial inflammation. Increased interleukin (IL)-2, IL-8, monocyte chemoattractant protein-1 (MCP-1), granulocyte-macrophage colony-stimulating factor (GMCSF) and keratinocyte-derived chemokine (KC) occurred on days 3 through 4. Increased IL-7 occurred on day 4. This study showed for the first time that inflammatory cytokines/chemokines in urine positively identified acute renal tubular injury in dogs at time points earlier than sCr, a traditional marker of nephrotoxicity.

Effects of enalapril in cats with pressure overload-induced left ventricular hypertrophy

In order to evaluate the effect of enalapril on haemodynamics and renal function in a pressure overload model, we prepared eight feline models of left ventricular hypertrophy (LVH) by banding of the aortic arch. The LVH cats were assigned to the placebo group or the enalapril group (0.5 mg/kg, PO, sid) 3 months following surgery, and each received its respective drug for 4 weeks. Each week, blood pressure, angiotensin converting enzyme (ACE) activity in blood, and creatinine clearance were measured, and complete blood count (CBC), biochemical examination of the blood, echocardiography, and chest radiography were carried out. The interventricular septum thickness (IVSd, IVSs), fractional shortening (FS), and ejection fraction (EF) increased significantly in the LVH cats following surgery (P<0.05). There was no significant difference between the placebo group and the enalapril group with respect to general physical parameters, CBC, biochemical parameters and renal function. In the enalapril group, systolic arterial pressure, mean arterial pressure, and ACE activity in blood decreased significantly following administration (P<0.05). In addition, the left ventricular free wall thickness in diastole and IVSd decreased significantly following administration (P<0.05). These results suggest that, in a pressure overload model, enalapril (0.5 mg/kg, sid) inhibits cardiac hypertrophy, reduces blood pressure, and does not adversely affect renal function.

Detecting early kidney damage in horses with colic by measuring matrix metalloproteinase -9 and -2, other enzymes, urinary glucose and total proteins

Background

The aim of the study was to investigate urine matrix metalloproteinase (MMP-2 and -9) activity, alkaline phosphatase/creatinine (U-AP/Cr) and gamma-glutamyl-transpeptidase/creatinine (U-GGT/Cr) ratios, glucose concentration, and urine protein/creatinine (U-Prot/Cr) ratio and to compare data with plasma MMP-2 and -9 activity, cystatin-C and creatinine concentrations in colic horses and healthy controls. Horses with surgical colic (n = 5) were compared to healthy stallions (n = 7) that came for castration. Blood and urine samples were collected. MMP gelatinolytic activity was measured by zymography.

Results

We found out that horses with colic had significantly higher urinary MMP-9 complex and proMMP-9 activities than horses in the control group. Colic horses also had higher plasma MMP-2 activity than the control horses. Serum creatinine, although within reference range, was significantly higher in the colic horses than in the control group. There was no significant increase in urinary alkaline phosphatase, gamma-glutamyltranspeptidase or total proteins in the colic horses compared to the control group. A human cystatin-C test (Dako Cytomation latex immunoassay^® based on turbidimetry) did not cross react with equine cystatin-C.

Conclusion

The results indicate that plasma MMP-2 may play a role in the pathogenesis of equine colic and urinary MMP-9 in equine kidney damage.

Effects of Long-Term Oral Administration of Ketoprofen in Clinically Healthy Beagle Dogs

To investigate the adverse effects of long-term administration of ketoprofen in dogs, ketoprofen (1 mg/kg) was administered to five clinically healthy beagle dogs (ketoprofen group) and gelatin capsules (control group) were administered to four clinically healthy beagle dogs for 30 days. We monitored the dogs through periodic physical examination, blood analyses, endoscopic examinations, fecal occult blood tests, renal function tests, urinalysis, urinary enzyme indices and cuticle bleeding time analysis. The lesions in the stomach, especially in the pyloric antrum, and fecal occult blood progressively worsened in the ketoprofen group. However, the differences between the ketoprofen group and the control group were not statistically significant. One dog in the ketoprofen group temporarily exhibited a decrease in renal plasma flow and two dogs exhibited enzymuria. However, these changes did not persist and the other examinations showed no significant difference between premedication and postmedication in the ketoprofen group. Therefore, the adverse effects of long-term administration of ketoprofen observed in this study were not clinically important in healthy dogs. Nevertheless, further investigation of adverse renal effects from long-term administration of ketoprofen is necessary in the dogs with subclinical renal disease.

Clinicopathological features in ovine AA amyloidosis

This paper describes the clinicopathological findings in sheep with AA amyloidosis. Serum samples from 12 AA amyloid-affected sheep and urine samples from 5 of these ewes were analyzed. In sera, the most important alteration was reflected in hypoalbuminemia, high concentration in beta and gamma-globulins and high levels of serum BUN, phosphorous and potassium. Serum creatinine, cholesterol and calcium concentrations showed no alterations. Urinary analysis showed proteinuria and a high protein/creatinine ratio. In three urine samples, high activities of urinary enzymes gamma-glutamyl transferase (GGT), beta-glucuronidase (GRS) and N-acetyl-beta-D-glucosaminidase (NAG) were observed, their ratios with urinary creatinine being increased for GGT and NAG and decreased for GRS. In conclusion, important alterations in biochemical and urinary parameters were observed in ovine affected by systemic AA amyloidosis. Those related to the activities of urinary enzymes could constitute reliable parameters for assessing renal injury in ovine AA amyloidosis.

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.

The circadian variation of urinary N-acetyl-beta-D-glucosaminidase and gamma-glutamyl transpeptidase in clinically healthy cats

The circadian variation of urinary N-acetyl-beta-D-glucosaminidase (NAG, EC 3.2.1.30) and gamma-glutamyl transpeptidase (gamma-GTP, EC 2.3.2.2) was evaluated in cats. Urine and blood were collected at 4-hr intervals from adult cats (3 males, 9 females) weighing between 2.6 and 5.0 kg. There was no circadian variation in the urine volume, creatinine clearance, creatinine excretion, NAG excretion or gamma-GTP excretion. The average NAG and gamma-GTP indices in the 4-hr urine were similar to those for the 24-hr urine. However, the variance for the 4-hr urine samples was higher than that of 24-hr urine. In conclusion, although 4-hr urine samples can be used to estimate 24-hr urinary enzyme excretion, short-term spot urine samples may cause increased variation in the enzyme index.

The variation in excretory urinary glycyl-prolyl dipeptidyl aminopeptidase in dogs

We studied the excretory variation of urinary glycyl-prolyl dipeptidyl aminopeptidase (GP-DAP, EC 3.4.14.5) in dogs. Adult domestic mongrel dogs (seven males and nine females, 7.5 to 13 kg bodyweight) which were considered to be healthy by laboratory tests were used. Urine and blood samples were obtained every four hours. Urine volume was measured for each sample and urine GP-DAP activity, and creatinine levels were determined. Creatinine clearance, creatinine excretion, GP-DAP activity and GP-DAP index (GP-DAP/Cr ratio) did not show any significant variation between the time periods. However, urine volume and urinary GP-DAP excretion significantly increased from 8:00 am to 12:00 pm. The GP-DAP index in spot urine samples showed low correlation with 24 hour GP-DAP excretion. In addition, a sex difference was observed in GP-DAP excretion. In conclusion, urinary GP-DAP excretion showed a circadian variation and sex difference. Therefore, GP-DAP in spot urine is not of use for the detection of renal disorders, and the 24-hour excretion value of GP-DAP should be determined.

Enzymuria as an index of renal damage in canine leishmaniasis

Urinary enzyme activities of alanine aminopeptidase, gamma-glutamyl transpeptidase, alkaline phosphatase, N-acetyl-beta-D-glucosaminidase and beta-glucuronidase were determined in 15 dogs with leishmaniasis and in a group of eight normal dogs. Serum creatinine and blood urea nitrogen concentrations were also measured and renal histology was examined. All the affected dogs had renal lesions. However, no significant differences in blood urea nitrogen and creatinine concentrations were found between the control group and the affected group. The urinary enzyme activities of gamma-glutamyl transpeptidase (P < 0.01), N-acetyl-beta-D-glucosaminidase (P < 0.01) and beta-glucuronidase (P < 0.05) were significantly higher in the affected dogs. Urinary enzymes therefore seem to be a more sensitive and reliable test for assessing early renal damage in canine leishmaniasis than serum creatinine or blood urea nitrogen concentrations.