Calculation of urinary enzyme excretion, with renal structure and function in dogs with pyometra

Renal tubular response to titanium dioxide nanoparticles exposure

Titatinum dioxide nanoparticles (TiO2-NPs) are frequently used in several areas. Titanium alloys are employed in orthopedic and odontological surgery (such as hip, knee, and teeth implants). To evaluate the potential acute toxic effects of titanium pieces implantations and in other sources that allow the systemic delivery of titanium, parenteral routes of TiO2-NPs administration should be taken into account. The present study evaluated the impact of subcutaneous administration of TiO2-NPs on renal function and structure in rats. Animals were exposed to a dose of 50 mg/kg b.w., s.c. and sacrificed after 48 h. Titanium levels were detected in urine (135 ± 6 ηg/mL) and in renal tissue (502 ± 40 ηg/g) employing inductively coupled plasma mass spectrometry. An increase in alkaline phosphatase activity, total protein levels, and glucose concentrations was observed in urine from treated rats suggesting injury in proximal tubule cells. In parallel, histopathological studies showed tubular dilatation and cellular desquamation in these nephron segments. In summary, this study demonstrates that subcutaneous administration of TiO2-NPs causes acute nephrotoxicity evidenced by functional and histological alterations in proximal tubule cells. This fact deserves to be mainly considered when humans are exposed directly or indirectly to TiO2-NPs sources that cause the systemic delivery of titanium.

Prospective evaluation of 5 urinary biomarkers as predictors of acute kidney injury in nonazotemic, hospitalized dogs

BACKGROUND

Early recognition of acute kidney injury (AKI) is hindered by current definitions and use of traditional, insensitive markers.

HYPOTHESIS/OBJECTIVES

Urinary (u) activity of γ-glutamyl transpeptidase (GGT) and alkaline phosphatase (ALP), and concentrations of heat-shock protein 70 (HSP70) and interleukins (ILs) -6 and -18, are predictive biomarkers for AKI and survival.

ANIMALS

Nonazotemic, hospitalized dogs (n = 118) and healthy controls (n = 20).

METHODS

A prospective observational study. Nonazotemic dogs at risk of AKI were recruited and their urinary biomarker concentrations were measured at presentation. Serum creatinine (sCr) and symmetric dimethylarginine (sSDMA) were measured daily until discharge/death.

RESULTS

The overall case fatality rate was 18.6%. Fifteen dogs (12.7%) developed AKI, which was associated with death (relative risk, 3.2; 95% confidence interval [CI], 1.57-6.55). All 5 urinary biomarkers were significantly higher in hospitalized dogs compared to controls, with minimal overlap. uHSP70/uCr, uGGT/uCr, and uIL-6/uCr at presentation were higher in dogs which later developed AKI. Areas under the receiver operator characteristic curve (AUROC) (95% CI) for the 3 biomarkers as predictors of AKI were 0.67 (0.51-0.83), 0.68 (0.55-0.81), and 0.78 (0.65-0.91), respectively. When they were categorically classified as elevated/normal, each additional elevated biomarker increased the odds for AKI (OR, 2.83; 95% CI, 1.23-6.52, P = .01). Agreement between sCr and sSDMA was poor (Cohen's kappa = .071). The AUROC of SDMA at presentation for AKI prediction was 0.73 (0.51-0.95).

CONCLUSIONS AND CLINICAL IMPORTANCE

Kidney injury was common, irrespective of subsequent worsening of azotemia or death. The predictive value of individual urinary biomarkers was reduced by moderate sensitivities and specificities. SDMA showed moderate discriminatory utility for AKI prediction, and often displayed discordant results with sCr.

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.

Renal expression and urinary excretion of aquaporin-2 in postobstructive uropathy in rats

This work assessed the time course of water renal management together with aquaporin-2 (AQP2) kidney expression and urinary AQP2 levels (AQP2u) in obstructive nephropathy. Adult male Wistar rats were monitored after 1, 2, and 7 days of bilateral ureteral release (bilateral ureteral obstruction (BUO); BUO-1, BUO-2 and BUO-7). Renal water handling was evaluated using conventional clearance techniques. AQP2 levels were assessed by immunoblotting and immunohistochemical techniques. AQP2 expression in apical membranes was downregulated in BUO-1 rats and upregulated both in BUO-2 and BUO-7 animals. AQP2 protein expression in whole cell lysate fraction from kidney cortex and medulla were significantly decreased in all the experimental groups. Concomitantly, mRNA levels of AQP2 decreased in renal medulla of all groups and in renal cortex from BUO-1; however, in renal cortex from BUO-2 and BUO-7 a recovery and an increase in the level of AQP2 mRNA were, respectively, observed. BUO-7 group showed a significant increase in AQP2u. The alterations observed in apical membranes AQP2 expression could explain, at least in part, the evolution time of water kidney management in the postobstructive phase of BUO. Additionally, the AQP2u increase after 7 days of ureteral release may be postulated as a biomarker of improvement in the kidney function.

Serial serum creatinine, SDMA and urinary acute kidney injury biomarker measurements in dogs envenomated by the European adder (Vipera berus)

Background

Acute kidney injury (AKI) is associated with high morbidity and mortality in dogs, but diagnosis may be impaired due the insensitivity of routine renal function biomarkers to detect earlier or milder forms of injury. Snake envenomation is one of several causes of AKI in dogs and humans. Dogs are commonly envenomated by the European adder (Vipera berus) between April and October each year, but few studies exist examining serial serum creatinine (sCr) and symmetric dimethylarginine (SDMA) measurements and AKI biomarkers in these dogs. Novel urinary biomarkers could improve clinical outcome by allowing earlier diagnosis of and intervention in AKI. The aim of this study was to assess the presence of AKI in dogs envenomated by V. berus at 12, 24 and 36 h after bite, as well as 14 days later, using sCr, SDMA and a panel of urinary AKI biomarkers normalised to urine creatinine (uCr), compared to a group of healthy control dogs.

Results

Thirty-five envenomated dogs and 35 control dogs were included. Serum creatinine did not exceed the upper reference limit at any time point in any dog after envenomation. Serum SDMA did not exceed 0.89 μmol/L in any dog. Compared to controls, urinary albumin/uCr, neutrophil gelatinase-associated lipocalin/uCr and monocyte chemotactic protein-1/uCr were significantly elevated 12 h (P <  0.0001, P <  0.0001, P = 0.01), 24 h (P <  0.001, P <  0.001, P = 0.002) and 36 h (P <  0.001, P <  0.001, P = 0.0008) after bite. Osteopontin/uCr was higher 24 and 36 h after bite (P < 0.0001), kidney injury molecule-1/uCr, interleukin-8/uCr and γ- glutamyl transferase/uCr were significantly higher 36 h after bite (P = 0.003, P = 0.0005, P = 0.001). Urinary cystatin C/uCr was not significantly different to controls at any timepoint. Biomarker/uCr ratios were not significantly different 14 days after envenomation compared to controls.

Conclusion

Urinary biomarker/Cr ratios are indicative of mild transient, non-azotaemic AKI in dogs envenomated by V. berus.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12917-021-02851-8.

Evaluation of urinary γ-glutamyl transferase and serum creatinine in non-azotaemic hospitalised dogs

Urinary and blood biomarkers for diagnosis of acute kidney injury (AKI) in hospitalised dogs were evalueted. This prospective study included 97 dogs, classified according to the International Renal Interest Society classification into no AKI and AKI grade 1 (48-hour increase in serum creatinine≥0.3 mg/dl and/or urinary production <1 ml/kg/hour for at least six hours). A total of 62 of 97 dogs (64 per cent) were classified as AKI 1. A statistically significant difference was found between no AKI and AKI 1 in urine protein to creatinine ratio, urinary γ-glutamyl transferase (uGGT) and uGGT/cu (P<0.0001). Thirteen of 97 dogs (13.4 per cent) that developed increased creatinine and change in AKI grade showed high mortality (n=9/13; 69.2 per cent). The receiver operating characteristic (ROC) curve analysis of uGGT/cu index as a marker for AKI grade 1 had an area under the ROC curve of 0.78; optimal cut-off point was 57.50 u/g, with sensitivity and specificity of 75.4 per cent and 75.6 per cent, respectively. Overall intensive care unit mortality was 23.7 per cent (23/97), 13.4 per cent (13/97) of which died during hospitalisation and 10.3 per cent (10/97) within 28 days after discharge. uGGT is an acceptable marker for distinguishing between AKI 1 and no AKI.

Renal Expression and Urinary Excretion of Na-K-2Cl Cotransporter in Obstructive Nephropathy

Renal damage due to urinary tract obstruction accounts for up to 30% of acute kidney injury in paediatrics and adults. Bilateral ureteral obstruction (BUO) is associated with polyuria and reduced urinary concentrating capacity. We investigated the renal handling of water and electrolytes together with the renal expression and the urinary excretion of the Na-K-Cl cotransporter (NKCC2) after 1 (BUO-1), 2 (BUO-2), and 7 (BUO-7) days of release of BUO. Immunoblotting and immunohistochemical studies showed that NKCC2 expression was upregulated in apical membranes both from BUO-2 and from BUO-7 rats. The apical membrane expression, where NKCC2 is functional, may be sufficient to normalize water, potassium, sodium, and osmolytes tubular handling. NKCC2 abundance in homogenates and mRNA levels of NKCC2 was significantly decreased in almost all groups suggesting a decrease in the synthesis of the transporter. Urinary excretion of NKCC2 was increased in BUO-7 groups. These data suggest that the upregulation in the expression of NKCC2 in apical membranes during the postobstructive phase of BUO could contribute to improving the excretion of sodium and consequently also the excretion of potassium, osmolytes, and water. Moreover, the increase in urinary excretion of NKCC2 in BUO-7 group could be a potential additional biomarker of renal function recovery.

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.

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.

Organic anion transporter 5 renal expression and urinary excretion in rats with vascular calcification

It has been described renal damage in rats with vascular calcification. The organic anion transporter 5 (Oat5) is only expressed in kidney, and its urinary excretion was proposed as potential early biomarker of renal injury. The aim of this study was to evaluate the Oat5 renal expression and its urinary excretion in an experimental model of vascular calcification in comparison with traditional markers of renal injury. Vascular calcification was obtained by the administration of an overdose of vitamin D₃ (300,000 IU/kg, b.w., i.m.) to male Wistar rats. Oat5 urinary abundance was evaluated by Western blotting. Traditional markers of renal injury, such as creatinine and urea plasma levels, urinary protein levels, and urinary alkaline phosphatase (AP) activity, were determined using commercial kits. Histology was assessed by hematoxylin/eosin staining. Oat5 renal expression was evaluated by Western blotting and by immunohistochemistry. An increased expression of Oat5 in renal homogenates, in apical membranes, and in its urinary excretion was observed in rats with vascular calcification. The traditional parameters used to evaluate renal function were not modified, with the exception of histology. It is possible to postulate the urinary excretion of Oat5 as a potential noninvasive biomarker of renal injury associated with vascular calcification.

Urinary biomarkers for acute kidney injury in dogs

Routinely, kidney dysfunction and decreased glomerular filtration rate (GFR) are diagnosed by the evaluation of changes in the serum creatinine (SCr) and blood urea nitrogen (BUN) concentrations. However, neither of these tests is sensitive or specific enough for the early diagnosis of impaired kidney function because they are both affected by other renal and nonrenal factors. Furthermore, kidney injury can be present in the absence of kidney dysfunction. Renal reserve enables normal GFR even when nephrons are damaged. Renal biomarkers, especially those present in urine, may be useful for the study of both acute and chronic nephropathies. The aim of this review is to describe the current status of urinary biomarkers as diagnostic tools for kidney injury in dogs with particular focus on acute kidney injury (AKI). The International Renal Interest Society (IRIS) canine AKI grading system and the implementation of urinary biomarkers in this system also are discussed. The discovery of novel urinary biomarkers has emerged from hypotheses about the pathophysiology of kidney injury, but few proteomic urine screening approaches have been described in dogs. Lack of standardization of biomarker assays further complicates the comparison of novel canine urinary biomarker validation results among studies. Future research should focus on novel biomarkers of renal origin and evaluate promising biomarkers in different clinical conditions. Validation of selected urinary biomarkers in the diagnosis of canine kidney diseases must include dogs with both renal and nonrenal diseases to evaluate their sensitivity, specificity as well as their negative and positive predictive values.

Clinical approach to advanced renal function testing in dogs and cats

Serum creatinine concentration is insensitive for detecting kidney injury and does not assist in differentiation between glomerular versus tubular damage. Advanced renal function tests, including glomerular filtration rate testing, determining fractional excretion of electrolytes, and assay of urine biomarkers, may allow earlier detection of reduced renal function mass, differentiation of renal from non-renal causes of azotemia, and assist with localization of damage. This article reviews the principles, indications, and limitations of these tests and describes their use in sample clinical scenarios.

Organic anion transporter 5 (Oat5) renal expression and urinary excretion in rats treated with cisplatin: a potential biomarker of cisplatin-induced nephrotoxicity

Cisplatin is one of the most potent chemotherapeutic antitumor drugs used in the treatment of a wide range of solid tumors. Its primary dose-limiting side effect is nephrotoxicity. The organic anion transporter 5 (Oat5) is exclusively localized in the kidney. Oat5 urinary excretion was recently proposed as a potential early biomarker of acute kidney injury (AKI). The aim of this study was to evaluate Oat5 renal expression and its urinary excretion in rats exposed to different doses of cisplatin, in comparison with traditional markers of renal injury, like renal histology, creatinine and urea plasma levels, creatinine clearance, protein and glucose urinary levels and urinary alkaline phosphatase (AP) activity. Male Wistar rats were treated with a single injection of cisplatin at different doses of 1, 2, 5 and 10 mg/kg b.w., i.p. (Cis1, Cis2, Cis5 and Cis10, n = 4, respectively) and experiments were carried out 48 h after cisplatin administration. The renal expression of Oat5 was evaluated by immunohistochemistry and Western blotting. Oat5 abundance, AP activity, creatinine, glucose and proteins were assayed in urine. Creatinine clearance and creatinine and urea plasma levels were also evaluated. In this experimental model, plasma urea and creatinine levels, creatinine clearance, AP urinary activity and protein and glucose urinary levels were significantly modified only at the highest cisplatin dose of 10 mg/kg b.w., i.p., as compared to control rats. In contrast, Oat5 urinary abundance was increased in a dose-related manner after the administration of cisplatin. Oat5 urinary abundance was elevated at a dose as low as 1 mg/kg b.w., i.p., implying renal perturbation, when no modifications of traditional markers of renal injury are yet observed. Oat5 renal expression was decreased in a dose-related manner, both in homogenates and apical membranes from cisplatin-treated kidneys. The increase in urinary Oat5 excretion might explain the decrease in the amount of Oat5 molecules in the renal tubule cells. Hence, the preclinical animal results showed in this work propose that Oat5 urinary excretion might potentially serve as a non-invasive early biomarker of cisplatin-induced AKI.

Gender related differences in kidney injury induced by mercury

The aim of this study was to determine if there are sex-related differences in the acute kidney injury induced by HgCl₂ since female rats express lower levels of renal Oat1 and Oat3 (transporters involved in renal uptake of mercury) as compared with males. Control males and females and Hg-treated male and female Wistar rats were employed. Animals were treated with HgCl₂ (4 mg/kg body weight (b.w.), intraperitoneal (i.p.)) 18 h before the experiments. HgCl₂ induced renal impairment both in male and female rats. However, female rats showed a lower renal impairment than male rats. The observed increase in kidney weight/body weight ratio seen in male and female rats following HgCl₂ treatment was less in the female rats. Urine volume and creatinine clearance decreased and Oat5 urinary excretion increased in both males and females, but to a lesser degree in the latter. Urinary alkaline phosphatase (AP) activity and histological parameters were modified in male but not in female rats after HgCl₂ administration. These results indicate that the lower Oat1 and Oat3 expression in the kidney of females restricts Hg uptake into renal cells protecting them from this metal toxicity. These gender differences in renal injury induced by mercury are striking and also indicate that Oat1 and Oat3 are among the main transporters responsible for HgCl₂-induced renal injury.

Long-term follow-up of renal function in dogs after treatment for ACTH-dependent hyperadrenocorticism

BACKGROUND

Systemic hypertension and proteinuria are frequent complications in dogs with Cushing's syndrome and do not always resolve after treatment of hypercortisolism. Therefore, dogs with Cushing's syndrome may be at risk for renal dysfunction before and after treatment.

HYPOTHESIS/OBJECTIVES

To assess renal function in dogs with ACTH-dependent hyperadrenocorticism (ADHAC) before and after treatment.

ANIMALS

A total of 19 dogs with ADHAC and 12 control dogs.

METHODS

Renal function was assessed before and at 1, 3, 6, and 12 months after treatment. Twelve dogs were treated with trilostane and 7 dogs by transsphenoidal hypophysectomy. Routine renal markers were measured and urinary albumin (uALB), immunoglobulin G (uIgG), and retinol-binding protein (uRBP) were assessed by ELISA. Urinary N-acetyl-β-D-glucosaminidase (uNAG) was determined colorimetrically. All urinary markers were indexed to urinary creatinine concentration (c). Plasma clearance of creatinine (Cl(creat)), exo-iohexol (Cl(exo)), and endo-iohexol (Cl(endo)) was used to measure glomerular filtration rate (GFR). Data were analyzed using a general linear model.

RESULTS

Serum creatinine and urea concentrations increased post-treatment, but remained within reference ranges. Plasma Cl(creat) and Cl(endo) were significantly lower post-treatment, whereas Cl(exo) was not different. Urinary protein-to-creatinine ratio (UPC), uALB/c, uIgG/c, and uRBP/c were decreased post-treatment, but at 12 months 5/13 dogs remained proteinuric. Urinary NAG/c did not change significantly.

CONCLUSIONS AND CLINICAL IMPORTANCE

A decrease in GFR and persistent proteinuria post-treatment may warrant the clinician's attention. Future research including renal histopathology of dogs with persistent proteinuria or low GFR is needed to further assess renal outcome.

Evaluation of kidney injury in dogs with pyometra based on proteinuria, renal histomorphology, and urinary biomarkers

BACKGROUND

Proteinuria is a feature of pyometra-associated renal dysfunction, but its prevalence and clinical relevance are not well characterized.

OBJECTIVES

To define which subset of dogs with pyometra has clinically relevant kidney injury by quantification of proteinuria; light, immunofluorescence, and electron microscopic examination of kidney biopsy specimens; and measurement of urinary biomarkers.

ANIMALS

Forty-seven dogs with pyometra. Ten clinically healthy intact bitches of comparable age.

METHODS

Prospective study. Routine clinicopathological variables including urinary protein to creatinine ratio (UPC) were analyzed. Validated assays were used to quantify urinary biomarkers for glomerular (urinary albumin, urinary immunoglobulin G, urinary C-reactive protein, urinary thromboxane B(2)) and tubular function (urinary retinol-binding protein, urinary N-acetyl-β-d-glucosaminidase). Kidney biopsy specimens from 10 dogs with pyometra and dipstick urine protein concentrations of 2+ or 3+ were collected during ovariohysterectomy. Urinalysis was repeated within 3 weeks after surgery in 9 of the 10 dogs.

RESULTS

UPC (median, range) was significantly higher in dogs with pyometra (0.48, 0.05-8.69) compared with healthy bitches (0.08, 0.02-0.16) (P < .01). Twenty-two of 47 dogs with pyometra had UPC>0.5, 12 had UPC>1.0, and 7 had UPC>2.0. Glomerulosclerosis and tubulointerstitial nephritis were common kidney biopsy findings in proteinuric dogs with pyometra. Dogs with glomerulosclerosis (5/10), either global or focal and segmental, had UPC>1.0 at ovariohysterectomy and afterward. Dogs with structural glomerular and tubular changes mostly had urinary biomarker to creatinine ratios above the 75th percentile.

CONCLUSION

Dogs with pyometra and UPC>1.0 or high ratios of urinary biomarkers appear likely to have clinically relevant renal histologic lesions and require monitoring after ovariohysterectomy. Future studies should evaluate the role of pyometra-associated pathogenic mechanisms in causing or exacerbating focal and segmental glomerulosclerosis in dogs.

Effect of Sampling Method and Storage Conditions on Albumin, Retinol-Binding Protein, And N-Acetyl-β-D-Glucosaminidase Concentrations in Canine Urine Samples

Urinary markers for renal dysfunction are gaining interest, but effects of sampling method, storage conditions, and urinary tract inflammation or infection on these markers are unclear. Therefore, the objectives of the current study were to determine the difference in urinary albumin (uALB), urinary retinol-binding protein (uRBP), and urinary N-acetyl-β-D-glucosaminidase (uNAG) concentrations in cystocentesis and voided samples and to investigate concentration changes after storage at −20°C and at −80°C. Effects of a protease inhibitor were also assessed in samples stored at −80°C for 12 months. In a pilot experiment, influence of in vitro hematuria, pyuria, and bacteriuria on the urinary markers was evaluated. A mixed model was used to calculate mean differences and 95% confidence intervals. Urinary ALB, uNAG, and uRBP concentrations were similar in voided and cystocentesis samples. After storage for 4 months at −20°C, uALB concentration was not affected, and uRBP concentration showed a mild and clinically irrelevant decrease, whereas uNAG activity was significantly lower compared with fresh samples. After storage for 12 months at −80°C, uALB and uRBP concentrations did not differ from fresh samples, but uNAG activity was severely decreased. Protease inhibitor addition did not preserve uNAG activity. Experimental hematuria, pyuria, and bacteriuria did not seem to affect urinary markers, although further research is needed.

Oat5 and NaDC1 protein abundance in kidney and urine after renal ischemic reperfusion injury

The aim of this study was to evaluate the abundance of the organic anion transporter 5 (Oat5) and the sodium-dicarboxylate cotransporter 1 (NaDC1) in kidney and urine after renal ischemic reperfusion injury. Renal injury was induced in male Wistar rats by occlusion of both renal pedicles for 0 (Group Sham), 5 (Group I5R60), or 60 (Group I60R60) min. The studies were performed after 60 min of reperfusion. The expression of Oat5 and NaDC1 was evaluated by IHC and Western blotting. Oat5 and NaDC1 abundance and alkaline phosphatase activity (AP) were assayed in urine. A decreased expression in renal homogenates and apical membranes and an increase in urinary excretion of Oat5 and NaDC1 were observed in I60R60 rats, as well as alterations of other widely used parameters for renal dysfunction and injury (plasma creatinine, urinary AP activity, kidney weight, histological lesions). In contrast, in the I5R60 group, only an increase in urinary excretion of Oat5 and mild histopathological damage was detected. This is the first study on Oat5 and NaDC1 detection in urine. These results suggest that urinary excretion of Oat5 might be an early indicator of renal dysfunction, which is useful for detection of even minor alterations in renal structural and functional integrity.

Renal histomorphology in dogs with pyometra and control dogs, and long term clinical outcome with respect to signs of kidney disease

Background

Age-related changes in renal histomorphology are described, while the presence of glomerulonephritis in dogs with pyometra is controversial in current literature.

Methods

Dogs with pyometra were examined retrospectively for evidence of secondary renal damage and persisting renal disease through two retrospective studies. In Study 1, light microscopic lesions of renal tissue were graded and compared in nineteen dogs with pyometra and thirteen age-matched control bitches. In Study 2, forty-one owners of dogs with pyometra were interviewed approximately 8 years after surgery for evidence ofclinical signs of renal failure in order to document causes of death/euthanasia.

Results

Interstitial inflammation and tubular atrophy were more pronounced in dogs with pyometra than in the control animals. Glomerular lesions classified as glomerular sclerosis were present in both groups. No unequivocal light microscopic features of glomerulonephritis were observed in bitches in any of the groups.

Two bitches severely proteinuric at the time of surgery had developed end stage renal disease within 3 years. In five of the bitches polyuria persisted after surgery. Most bitches did not show signs of kidney disease at the time of death/euthanasia.

Conclusion

Tubulointerstitial inflammation was observed, but glomerular damage beyond age-related changes could not be demonstrated by light microscopy in the dogs with pyometra. However, severe proteinuria after surgery may predispose to development of renal failure.

Cardiac troponin I levels in canine pyometra

BACKGROUND

Myocardial injury may contribute to unexpected deaths due to pyometra. To detect myocardial damage, measurement of cardiac troponin I (cTnI) is currently the most sensitive and specific method. The aims of the present study were to evaluate presence of myocardial damage in canine pyometra by analysis of cTnI, to explore whether myocardial injury was associated with systemic inflammatory response syndrome (SIRS) and to evaluate whether other clinical or laboratory parameters were associated with cTnI increase.

METHODS

Preoperative plasma levels of cTnI were investigated in 58 female dogs with pyometra and 9 controls. The value of physical examination findings, haematological, serum biochemical and pro-inflammatory (CRP and TNF-alpha) parameters as possible predictors of increased cTnI levels was also evaluated.

RESULTS

Seven dogs with pyometra (12%) and one control dog (11%) had increased levels of cTnI. In the pyometra group, the levels ranged between 0.3-0.9 microg l-1 and in the control dog the level was 0.3 microg l-1. The cTnI levels did not differ significantly between the two groups. No cardiac abnormalities were evident on preoperative physical examinations. Four of the pyometra patients died within two weeks of surgery, of which two were examined post mortem. In one of these cases (later diagnosed with myocarditis and disseminated bacterial infection) the cTnI levels increased from 0.9 microg l-1 preoperatively to 180 microg l-1 the following day when also heart arrhythmia was also detected. The other patient had cTnI levels of 0.7 microg l-1 with no detectable heart pathology post mortem. CTnI increase was not associated with presence of SIRS. There was a trend for the association of cTnI increase with increased mortality. No preoperative physical examination findings and few but unspecific laboratory parameters were associated with increased cTnI levels.

CONCLUSION

Increased cTnI levels were observed in 12% of the dogs with pyometra. The proportions of dogs with cTnI increase did not differ significantly in the pyometra group compared with the control group. CTnI increase was not associated with presence of SIRS. A trend for association of cTnI increase and mortality was observed. Preoperative physical examination findings and included laboratory parameters were poor predictors of increased cTnI levels.

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.

Safety of reduced-dosage ketoprofen for long-term oral administration in healthy dogs

OBJECTIVE

To evaluate the safety of reduced-dosage ketoprofen (RDKET) for long-term oral administration in healthy dogs.

ANIMALS

14 healthy Beagles.

PROCEDURES

Racemic ketoprofen (0.25 mg/kg, PO) and gelatin capsules, as a drug-free placebo, were each administered to 7 dogs for 30 days. Dogs were periodically monitored via physical examination, blood analyses, endoscopic examinations, fecal occult blood tests (tetramethylbenzidine and guaiac methods), renal function tests (effective renal plasma flow and glomerular filtration rate), urinalyses, urinary enzyme indices (N-acetyl-beta-D-glucosaminidase and gamma-glutamyl-transferase), and hemostatic function tests (buccal mucosa bleeding time, cuticle bleeding time, prothrombin time, activated partial thromboplastin time, and fibrinogen concentration).

RESULTS

Pyloric antrum lesion grade was significantly higher in the RDKET group on day 28, compared with the pretreatment and control group grades. Fecal occult blood grade measured by use of the tetramethylbenzidine method was significantly higher in the RDKET group on day 30, compared with the pretreatment grade. No other significant differences were detected between treatment groups.

CONCLUSIONS AND CLINICAL RELEVANCE

RDKET induced mild to moderate gastric mucosal injuries especially in the pyloric antrum in healthy Beagles, whereas no adverse effects were observed in renal function or hemostasis. Fecal occult blood tests may be useful as screening tests for adverse gastrointestinal effects induced by RDKET in dogs.

Evaluation of adverse effects of long-term orally administered carprofen in dogs

OBJECTIVE

To evaluate the adverse effects of carprofen in dogs after oral administration for 2 months.

DESIGN

Prospective, randomized, blinded, placebo-controlled clinical trial.

ANIMALS

22 dogs with osteoarthritis in the hip or elbow joint.

PROCEDURE

13 dogs received orally administered carprofen daily for 2 months, and 9 dogs received a placebo for 2 months. Dogs were weighed, and serum and urine samples were collected before initiation of treatment and 4 and 8 weeks after initiation of treatment. Serum concentrations of total protein, albumin, urea, and creatinine and serum activities of alkaline phosphatase (ALP) and alanine aminotransferase (ALT) were measured. Urinary ALP-to-creatinine, gamma-glutamyltransferase (GGT)-to-creatinine, and protein-to-creatinine ratios were calculated. Dogs were observed by owners for adverse effects.

RESULTS

Serum protein and albumin concentrations were lower in treated dogs than in those that received placebo at 4 weeks, but not at 8 weeks. No changes were observed in serum urea or creatinine concentrations; ALP or ALT activity; or urinary ALP-to-creatinine, GGT-to-creatinine, or protein-to-creatinine ratios. Dogs' weights did not change. Severity of vomiting, diarrhea, and skin reactions did not differ between groups, but appetite was better in dogs receiving carprofen than in dogs in the placebo group.

CONCLUSIONS AND CLINICAL RELEVANCE

It is possible that the transient decreases in serum protein and albumin concentrations in dogs that received carprofen were caused by altered mucosal permeability of the gastrointestinal tract because no indications of renal or hepatic toxicity were observed. Carprofen appeared to be well tolerated by dogs after 2 months of administration.

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.

Vasopressin secretion in response to osmotic stimulation and effects of desmopressin on urinary concentrating capacity in dogs with pyometra

OBJECTIVE

To determine vasopressin (VP) secretory capacity during osmotic stimulation and the response to desmopressin treatment in dogs with pyometra and control dogs.

ANIMALS

6 dogs with pyometra before and after ovariohysterectomy and 6 control dogs.

PROCEDURE

Urine osmolality (Uosm) was measured during 12 hours. Values measured on the first day defined the basal Uosm pattern. On the second day, dogs were given desmopressin to induce a desmopressin-stimulated Uosm pattern. On day 3, the VP response to osmotic stimulation was examined.

RESULTS

Median Uosm on day 1 was 340 mOsm/kg (range, 104 to 1,273 mOsm/kg) and 807 mOsm/kg (range, 362 to 1,688 mOsm/kg) in dogs with pyometra before and after surgery, respectively, and 1,511 mOsm/kg (range, 830 to 1,674 mOsm/kg) in control dogs. Median Uosm during desmopressin treatment was 431 mOsm/kg (range, 168 to 1,491 mOsm/kg) and 1,051 mOsm/kg (range, 489 to 1,051 mOsm/kg) in dogs with pyometra before and after surgery, respectively, and 1,563 mOsm/kg (range, 1,390 to 2,351) in control dogs. In dogs with pyometra, threshold for VP secretion was lower before surgery (median, 340 mOsm/kg; range, 331 to 366 mOsm/kg) than after surgery (median, 358 mOsm/kg; range, 343 to 439 mOsm/kg) or in control dogs (median, 347 mOsm/kg; range, 334 to 360 mOsm/kg). Highest maximum plasma VP values were found in dogs with pyometra.

CONCLUSIONS AND CLINICAL RELEVANCE

Dogs with pyometra had increased urine concentration in response to desmopressin but not to the degree of control dogs, whereas VP secretory ability was not reduced.

Canine pyometra: a study of the urinary proteins by SDS–PAGE and Western blot

Canine pyometra often causes glomerulonephritis by immune complex deposition in the glomeruli. Proteinuria, ranging from moderate to severe, may be present secondary to renal damage. To determine urinary protein excretion due to pyometra, sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) was conducted on urine from 15 bitches with pyometra and 10 healthy bitches. To characterize urinary immunoglobin excretion, Western blot analysis of the urine samples using antibodies to canine IgG and IgA was also performed. Nine bands were detected by electrophoresis in bitches with pyometra, while only four were detected in the healthy animals. The urinary proteins from bitches with pyometra were primarily of glomerular origin; 58% were of medium-high molecular weight (MW), and the remainder were low MW. None of the healthy dogs had IgG or IgA in their urine, whereas three bitches with pyometra had IgG in their urine and another bitch with pyometra had both IgG and IgA. The low proportion of bitches with urinary immunoglobins was probably be due to early diagnosis of the disease. Although only a limited number of dogs was used, this study is apparently the first to characterize the electrophoretic pattern of urinary proteins and to quantify urinary excretion of IgG and IgA in bitches with pyometra.

Creatinine in the Dog: A Review

Creatinine is the analyte most frequently measured in human and veterinary clinical chemistry laboratories as an indirect measure of glomerular filtration rate (GFR). Although creatinine metabolism and the difficulties of creatinine measurement have been reviewed in human medicine, similar reviews are lacking in veterinary medicine. The aim of this review is to summarize information and data about creatinine metabolism, measurement, and diagnostic significance in the dog. Plasma creatinine originates from the degradation of creatine and creatine phosphate, which are present mainly in muscle and in food. Creatinine is cleared by glomerular filtration with negligible renal secretion and extrarenal metabolism, and its clearance is a good estimate of GFR. Plasma and urine creatinine measurements are based on the nonspecific Jaffé reaction or specific enzymatic reactions; lack of assay accuracy precludes proper interlaboratory comparison of results. Preanalytical factors such as age and breed can have an impact on plasma creatinine (P-creatinine) concentration, while many intraindividual factors of variation have little effect. Dehydration and drugs mainly affect P-creatinine concentration in dogs by decreasing GFR. P-creatinine is increased in renal failure, whatever its cause, and correlates with a decrease in GFR according to a curvilinear relationship, such that P-creatinine is insensitive for detecting moderate decreases of GFR or for monitoring progression of GFR in dogs with severely reduced kidney function. Low sensitivity can be obviated by determining endogenous or exogenous clearance rates of creatinine. A technique for determining plasma clearance following IV bolus injection of exogenous creatinine and subsequent serial measurement of P-creatinine does not require urine collection and with additional studies may become an established technique for creatinine clearance in dogs.