Symmetric Dimethylarginine Assay Validation, Stability, and Evaluation as a Marker for the Early Detection of Chronic Kidney Disease in Dogs

Symmetric and asymmetric dimethylarginines in healthy and colic horses

This study investigated the plasma concentrations of symmetric dimethylarginine (SDMA) and asymmetric dimethylarginine (ADMA) in healthy horses and in horses affected by colic in relation to the type of colic and systemic inflammation response syndrome (SIRS) status. Upon admission (T0), horses underwent a physical examination, and the SIRS status was assessed. The horses with colic were divided retrospectively based on the type of colic, SIRS status, treatment, and outcome. SDMA and ADMA levels were measured at T0 and then every 24 h at four time points (T1, T2, T3, T4). Differences between groups (healthy, non-strangulating intestinal obstruction, strangulating intestinal obstruction, SIRS-positive, and SIRS-negative) were analysed with the Kruskal-Wallis test. Changes within groups over time were assessed using Friedman's two-way analysis of variance by ranks. Generalized linear mixed models (GLMMs) were used to analyze SDMA and ADMA levels in colic horses. Diagnostic accuracy was assessed using receiver operating characteristic curves, cut-off values, area under the curve analysis, and 95 % confidence intervals. SDMA concentrations were significantly lower in healthy horses compared to colic patients across all sampling times. ADMA levels were significantly higher at T2 in strangulating colic and SIRS-positive horses compared to healthy horses. GLMM analysis revealed no differences in SDMA or ADMA concentrations based on colic type, SIRS status, treatment, or outcome. Neither SDMA nor ADMA appeared to offer clinical utility as biomarkers in distinguishing between strangulating and non-strangulating colic or SIRS-positive and negative horses.

New biomarkers and scintigraphic evaluation of renal function in dogs with canine leishmaniosis

This study evaluated the utility of new renal biomarkers in canine leishmaniosis (CanL). A total of 6 healthy dogs (CG) and 22 dogs with CanL (LeishVet stage III or GIII (n = 11) and stage IV or GIV (n = 11)) were included. Plasma creatinine, urea, cystatin C (pCysC), and symmetric dimethylarginine were analyzed. In urine, neutrophil gelatinase-associated lipocalin, retinol-binding protein, Tamm-Horsfall protein, and total protein were measured using their ratios with creatinine (uNGAL/c, uRBP/c, uTHP/c, and UPC, respectively). The estimated glomerular filtration rate (eGFR) was assessed by 99mTc-DTPA scintigraphy. All glomerular biomarkers strongly correlated with eGFR and showed statistically significant differences between CanL stages but not with CG, except for pCysC, which was particularly noteworthy for its statistical significance, instilling confidence in its potential use. All tubular biomarkers presented significant differences between GIV and CG; however, only uNGAL/c and uTHP/c differentiated between GIII and CG. Moreover, none could distinguish between the GIII and GIV groups. These data suggest that the new glomerular biomarkers could help determine stages of renal disease in CanL. uNGAL/c and uTHP/C showed advantages in making an earlier diagnosis. Ultimately, pCysC presented tremendous potential, as it was statistically significant for both uses. This research provides valuable information to understand the behavior of these biomarkers in renal disease secondary to CanL.

Renal Biomarkers in Companion Animals-A Review

Recent advancements in molecular biology have led to the discovery of potential biomarkers for the diagnosis of acute kidney disease (AKD) and chronic kidney disease (CKD). The use of multiple biomarkers in the diagnosis of kidney disease has the potential to enhance both specificity and sensitivity, enabling early detection and intervention that could ultimately reduce morbidity and mortality rates. This review provides an overview of studies on urine and blood biomarkers and examines their utility and significance in various clinical settings. Further and continuous research is needed to support the application of these biomarkers in clinical practice to facilitate early diagnosis, guidance for different interventions, and the monitoring of disease progression.

A Retrospective Evaluation of Serum Symmetric Dimethylarginine Concentration in Dogs With Protein-Losing Enteropathy

BACKGROUND

Serum symmetric dimethylarginine (SDMA) is abnormally increased in people with inflammatory bowel disease (IBD). Changes in dogs with gastrointestinal disease, such as protein-losing enteropathy (PLE), have not been assessed.

OBJECTIVES

Evaluate SDMA concentration in non-azotemic dogs with PLE.

ANIMALS

A total of 127 client-owned dogs, 17 with PLE, 34 controls matched for age, breed, sex, and neuter status, and 76 additional controls for multiple linear regression modeling.

METHODS

Retrospective case-control study. The clinical records of a United Kingdom referral hospital were reviewed. Dogs with azotemia or prior glucocorticoid or immunosuppressive treatment were excluded. Dogs diagnosed with PLE that had serum symmetric dimethylarginine (SDMA) concentrations measured were compared with the matched controls. Signalment, clinical presentation, clinicopathological abnormalities, treatment, and SDMA concentration pre- (PLE-T0) and post- (PLE-T1) treatment were recorded.

RESULTS

At baseline, SDMA concentration was higher in PLE (T0, 15.2 ± 2.02 μg/dL) than in control (11.0 ± 3.13 μg/dL) dogs (p < 0.001; Hedge's G, 1.48), but decreased with treatment (PLE-T1: 10.3 ± 2.78 μg/dL; T0 vs. T1: p = 0.01, Hedge's G, 1.31). Serum creatinine concentration was similar in PLE (T0, 0.81 ± 0.24 μg/dL) and control (0.85 ± 0.26 μg/dL) dogs at baseline (p = 0.57; Hedge's G, 0.18). Serum albumin concentration was lower in PLE (1.60 ± 0.51 g/dL) than in control (2.96 ± 0.49 g/dL) dogs (p < 0.001; Hedge's G, 2.68) before treatment, but increased with treatment (PLE-T1: 2.29 ± 0.65 g/dL; T0 vs. T1: p = 0.003; Hedge's G, 1.14), although it remained lower than the concentration in controls (p = 0.002; Hedge's G, 1.23). No other clinicopathological differences were evident.

CONCLUSIONS AND CLINICAL IMPORTANCE

Serum SDMA concentration is increased in dogs with PLE; the clinical relevance of this finding requires further investigation.

Influence of Carcinoma and Sarcoma on Neutrophil Gelatinase-Associated Lipocalin and Symmetric Dimethylarginine Concentrations in Dogs

BACKGROUND

It is unknown if tumors or concomitant renal disease influence neutrophil gelatinase-associated lipocalin (NGAL) and symmetric dimethylarginine (SDMA) concentrations in tumor-bearing dogs.

OBJECTIVES

Determine the effect of tumor presence, tumor type, and metastasis on concentrations of serum NGAL (sNGAL), SDMA, urinary NGAL (uNGAL), and uNGAL-to-creatinine ratio (uNGAL/Cr) in dogs with carcinoma or sarcoma without clinically relevant renal disease.

ANIMALS

Twenty-one dogs with carcinoma, 18 with sarcoma, and 20 healthy age-controlled dogs.

METHODS

Concentrations of sNGAL, SDMA, and uNGAL, and uNGAL/Cr ratio were measured from banked samples collected during a previous prospective study. Patient clinicopathological and histopathology records were reviewed, and those with renal azotemia or moderate to severe histopathological renal abnormalities were classified as having clinically relevant renal disease. Biomarker concentrations were compared between tumor-bearing dogs without clinically relevant renal disease and healthy age-controlled dogs. Additionally, comparisons were made between dogs with carcinoma and sarcoma, as well as between dogs with and without metastasis. Correlations between uNGAL and sNGAL concentrations, along with acute phase protein (APP) concentrations, were also analyzed.

RESULTS

Tumor-bearing dogs without clinically relevant renal disease had increased uNGAL/Cr (p < 0.001), but not sNGAL, compared with healthy controls. Although median SDMA concentrations did not significantly differ between groups, increased concentrations were found in 32% of dogs with carcinoma and 20% of dogs with sarcoma. No differences were found between dogs with carcinoma and those with sarcoma, or between dogs with metastasis and those without. Urinary and serum NGAL concentrations were moderately correlated, while weak to no correlations were observed with APPs.

CONCLUSION

Carcinomas and sarcomas, but not metastasis, influence uNGAL/Cr and SDMA concentrations in dogs.

Evaluation of renal function in dogs using pulsed Doppler ultrasonography

Background

In human medicine, efforts have been made to evaluate venous blood flow in the kidneys to diagnose renal disease and estimate renal function. In dogs, previous studies have predicted renal function using the resistive index (RI) and pulsatility index (PI), which are derived from renal arterial blood flow velocity assessed via pulsed Doppler ultrasonography. However, to date, no study has been conducted on renal venous blood flow velocity in dogs.

Aim

To investigate the relationship between renal venous blood flow velocity and renal function.

Methods

Ten normal beagle dogs underwent blood tests and glomerular filtration rate (GFR) measurements. Pulsed Doppler ultrasonography was performed under sedation to measure the maximum venous flow velocity (Vmax), minimum venous flow velocity (Vmin), and venous impedance index in the renal and interlobular veins. The RI and PI were calculated from the renal and interlobular arteries.

Results

Vmax and Vmin of the renal vein were negatively correlated with GFR in both kidneys. No significant correlations were found between other measures and GFR. These results suggest a relationship between GFR and venous flow velocity in the renal veins assessed using pulsed Doppler ultrasonography.

Conclusion

These findings demonstrate the potential of this methodology as a new tool for predicting abnormalities in the renal venous blood flow and renal congestion in dogs. Further large-scale studies and comparisons between healthy dogs and dogs with impaired renal function are needed to validate this relationship.

Diagnostic validation of the urine albumin-to-creatinine ratio for early renal disease in healthy dogs and dogs with chronic kidney disease

IMPORTANCE

This paper highlights the urine albumin-to-creatinine ratio (UAC) as a valuable biomarker for the early detection of chronic kidney disease (CKD) in dogs. The UAC effectively distinguishes between healthy dogs and those with CKD, particularly in the early stages, and enhances diagnostic accuracy when used alongside other renal biomarkers.

OBJECTIVE

To evaluate the utility of the UAC as a biomarker for early CKD diagnosis in dogs and examine its correlation with other renal biomarkers in a large-scale clinical study.

METHODS

This study included 99 healthy dogs and 122 dogs with CKD. The UAC and other renal biomarkers were measured and evaluated in healthy dogs and those with CKD and categorized according to the staging criteria of the International Renal Interest Society (IRIS).

RESULTS

Dogs with CKD had significantly higher UACs than healthy dogs (p < 0.05). The UAC correlated with the IRIS stages and other renal biomarkers (p < 0.05). Receiver operating characteristic curve analysis yielded an area under the curve of 0.817 (p < 0.05) for the UAC, with a cut-off value of 19.20 mg/g, showing 72% sensitivity and 71% specificity. A "grey zone" diagnostic window for early-stage CKD was introduced.

CONCLUSIONS AND RELEVANCE

The UAC is effective for the early diagnosis of renal disease in dogs. The UAC can differentiate between healthy dogs and those with CKD at IRIS stage 1. The diagnostic value is enhanced when used alongside other renal biomarkers, allowing for more specific guidelines for pet owners and veterinarians. This large-scale study addresses the limitations of previous research conducted on small clinical samples.

Urinary neutrophil gelatinase-associated lipocalin as early biomarker for renal disease in dogs with leishmaniosis

Canine leishmaniosis (CanL), caused by Leishmania sp., presents a wide array of symptoms; renal dysfunction is frequently observed in these dogs and is associated with a poor prognosis and increased mortality. The traditional biomarkers namely urea and creatinine can detect renal damage but only in advanced stages of the disease. However, it has been shown that the symmetric dimethylarginine assay (SDMA) or the protein/creatinine ratio (UPC) and are early biomarkers of renal dysfunction. Their elevation occurs earlier than that of creatinine, but other novel biomarkers such as neutrophil gelatinase-associated lipocalin (NGAL) are currently under investigation. Our objective was to determine whether the urine NGAL-creatinine ratio (uNGAL/c) can provide very early diagnosis of kidney disease in CanL. In total, 68 dogs were included in the study: 15 healthy dogs and 53 dogs with CanL who were classified according to International Renal Interest Society (IRIS) classification: IRIS 1 (N= 34), IRIS 2 (N= 9) and IRIS 3/4 (N= 10). IRIS 1 was subdivided according to proteinuria in IRIS 1NP (13 dogs with UPC < 0.2), IRIS 1BL (8 dogs with UPC = 0.2-0.5) and IRIS 1 P (13 dogs with UPC > 0.5). Blood samples were collected for complete hematological and biochemistry analysis including plasma NGAL. Urinalysis included specific gravity, UPC, CysC and NGAL expressed as a ratio with creatinine. The mean concentrations of pCysC and SDMA in CanL, show a statistically significant increase from IRIS 1NP, not being statistically significant for pCysC in the IRIS 1BL group. The UPC show a statistically significant increase from IRIS 1NP. In all groups with CanL for uCysC/c and uNGAL/c was observed a statistically significant increase. The uNGAL/c in the group proteinuric animals, presents a positive correlation with all renal biomarkers studied. In the group of non-proteinuric animals, the uNGAL/c presents a positive correlation with SDMA and UPC. The uNGAL/c can be considered a reliable indicator of renal disease in dogs diagnosed with CanL who are non-azotemic and non-proteinuric.

Glomerular filtration rate determined by measuring serum clearance of iohexol in unanesthetized cheetahs (Acinonyx jubatus) with comparison to serum symmetric dimethylarginine

One of the more common diseases affecting zoo-managed cheetahs (Acinonyx jubatus) is chronic renal disease, which can impact their welfare and ultimately shortens their lifespan. Early diagnosis, for which estimating Glomerular Filtration Rate (GFR) is one such tool, is imperative to help mitigate the negative impacts of this insidious disease. GFR was determined by measuring the serum clearance of iohexol in nine clinically normal, cheetahs managed under human care that presented for voluntary blood collection. A 2-sample iohexol clearance method was performed, along with serum symmetric dimethylarginine (SDMA) determination. SDMA has shown promise in humans, dogs, and cats, as an early biomarker of renal disease. Additionally, the relationship between GFR and SDMA, along with serum creatinine and BUN were analyzed. The mean values for the uncorrected GFR and corrected GFR were 2.08 ± 0.215 mL/min/kg body weight and 1.87 ± 0.173 mL/min/kg body weight, respectively. No significant correlations were observed between GFR, SDMA, serum creatinine, or BUN. Both the uncorrected and corrected iohexol-based GFR values were similar to an inulin-based GFR reference interval determined in zoo managed cheetahs and a reported domestic cat iohexol-based GFR reference interval. Serum SDMA values support previous research suggesting cheetahs have a separate reference interval from domestic cats (0-14 μg/dL). Measuring GFR by the serum clearance of iohexol shows promise as a readily available, cheap, and easily administered clearance marker that can be used in cheetahs trained for voluntary blood collection, thereby avoiding the need for anesthesia.

Levopositioned caudal vena cava and circumcaval left ureter with subsequent hydronephrosis and hydroureter in a dog

The presentation and investigation of a levopositioned caudal vena cava, a rare congenital vascular abnormality seen mainly in Bernese Mountain Dogs, which resulted in ureteral compression, hydronephrosis and hydroureter. Surgical transection, transposition and anastomosis were performed to reposition the circumcaval ureter. A 19-month-old male neutered Bernese Mountain Dog was presented with a 13-month history of vague signs including intermittent abdominal pain, inappetence and diarrhoea, which were poorly responsive to medical management. Abdominal ultrasound revealed left-sided hydronephrosis and hydroureter. Further investigation included abdominal computed tomography and pre- and post-intravenous iodinated contrast, which revealed a levopositioned caudal vena cava with associated ureteral displacement to a circumcaval position, resulting in ureteral compression and proximal dilation affecting both the proximal ureter and the left kidney. The patient was also found to have concomitant gall bladder agenesis. Surgery was performed to transect, transpose and anastomose the ureter in a normal anatomical position, and the patient made an excellent clinical recovery. All gastrointestinal signs resolved within 2 weeks of surgery and remained resolved 12 months later. Follow-up ultrasound and pyelography were performed at 4-month post-surgery, revealing a mild improvement in the hydronephrosis and hydroureter. Although rare, circumcaval ureter should be considered a differential in dogs presenting with hydroureter and hydronephrosis, especially Bernese Mountain Dogs.

Assessment of cell cycle arrest biomarkers and neutrophil gelatinase-associated lipocalin to distinguish acute kidney injury from other diseases in dogs

BACKGROUND

Cell cycle arrest biomarkers (tissue inhibitor of metalloproteinase-2 [uTIMP-2] and insulin-like growth factor binding protein 7 [uIGFBP7]), and neutrophil gelatinase-associated lipocalin (NGAL) variables are valuable biomarkers for early diagnosis of acute kidney injury (AKI) in people.

OBJECTIVES

To evaluate uTIMP-2, uIGFBP7, fractional excretion of NGAL (FeNGAL), and urinary to serum NGAL ratio (u/sNGAL) in healthy dogs, dogs with AKI, dogs with chronic kidney disease (CKD), and critically ill (CI) dogs.

ANIMALS

Forty-two client-owned dogs (healthy, n = 10; AKI, n = 11; CKD, n = 11; CI, n = 10).

METHODS

Prospective, observational study. After assessment of routine renal biomarkers, stress (uTIMP-2, uIGFBP7) and damage (NGAL) biomarkers were measured, using ELISA kits, and normalized to urinary creatinine (uCr).

RESULTS

Normalized uTIMP-2 and [uTIMP-2] × [uIGFBP7]/uCr were significantly higher in the AKI group (median 151.9 [range, 2.2-534.2] and 62.9 [1.1-266.8] pg/mL respectively), compared to healthy dogs (0.3 [0.2-74.7]; P < .001 and 0.16 [0.1-58.1] pg/mL; P < .001), dogs with CKD (0.7 [0.3-742.5]; P = .04 and 0.37 [0.2-180.1] pg/mL; P = .03) and CI dogs (1.9 [0.2-37.0]; P = .03 and 0.8 [0.1-16.1] pg/mL; P = .02). Fractional excretion of NGAL was significantly higher in dogs with AKI (54.17 [7.93-155.32] %), than in healthy (0.03 [0.01-0.21] %; P < .001) and CI dogs (3.05 [0.05-28.86] %; P = .02).

CONCLUSIONS AND CLINICAL IMPORTANCE

Normalized uTIMP-2, [uTIMP-2] × [uIGFBP7]/uCr, and FeNGAL can be valuable renal biomarkers for early diagnosis of AKI in dogs.

Early Detection of Chronic Kidney Disease Using Plasma Neutrophil Gelatinase-Associated Lipocalin and Kidney Injury Molecule-1 in Small-Breed Dogs: A Retrospective Pilot Study

Multiple diagnostic modalities are urgently needed to identify early-stage kidney diseases. Various molecules have been investigated; however, most studies have focused on identifying specific biomarkers in urine. Considering that assessing the symmetrical dimethylarginine (SDMA) plasma concentration is more suitable as an early diagnostic test for chronic kidney disease (CKD) in routine veterinary practice, we aimed to investigate the clinical usefulness of plasma neutrophil gelatinase-associated lipocalin (pNGAL) and plasma kidney injury molecule-1 (pKIM-1) concentrations for CKD detection in small-breed dogs. Through a retrospective analysis, we found that numerous clinicopathological data showed a log-normal distribution, even when they satisfied normality tests. Moreover, the log-transformed pNGAL and pKIM-1 concentrations successfully identified CKD International Renal Interest Society (IRIS) stages 1-4 and the risk group with underlying CKD risk factors. Correlation analysis and group comparison of other factors confirmed the possibility of using these two biomarkers for detecting the CKD risk group and IRIS stage 1. Receiver operating characteristic curve analysis revealed that the diagnostic accuracy for discriminating the risk group was superior in the order of pKIM-1, pNGAL, SDMA, and serum creatinine levels. In conclusion, these results suggest that pKIM-1 and pNGAL are possible early or quantifiable markers of insignificant CKD or can be at least used as an adjunct with traditional indicators.

Reference Interval Creation for Symmetric Dimethylarginine (SDMA) in Healthy Hispaniolan Amazon Parrots (Amazona ventralis) and Quaker Parrots (Myiopsitta monachus)

Renal disease is often identified as a cause of morbidity and mortality in avian patients. However, currently, early antemortem detection of renal disease in avian patients is difficult. Anatomical and physiological differences between mammals and birds mean the use of commonly employed diagnostic testing (ie, measurement of blood urea nitrogen [BUN] and serum creatinine, urinalysis, and ultrasonography) are either nondiagnostic or difficult to achieve. Symmetric dimethylarginine (SDMA) is considered a more sensitive marker for renal disease in humans, dogs, and cats. However, SDMA has not yet been assessed for diagnostic use in any psittacine species. In this study, we establish reference ranges for SDMA in both Hispaniolan Amazon parrots (Amazona ventralis, HAP) and Quaker parrots (Myiopsitta monachus, QP). Blood was collected from 23 Amazon parrots and 32 Quaker parrots maintained in research facilities. Measurement of SDMA through a commercially available immunoassay (IA-SDMA) as well as creatinine, BUN, uric acid, phosphorus, calcium, sodium, potassium, and chloride were determined through IDEXX Laboratories. Plasma SDMA concentrations ranged from 6 to 15 µg/dL and 3 to 15 µg/dL for the HAP and QP, respectively. Sex was a confounding factor for the QP population, but sex did not have a significant effect on SDMA for the HAP population. No significant correlations were identified between SDMA concentrations and other parameters in either psittacine species. Our results show proof of concept for the IA-SDMA and provide reference intervals for SDMA in HAP and QP. Further investigation is required to determine the validity of this assay and the predictive power of SDMA in the detection of renal impairment for parrots and other common companion birds.

Investigation of symmetric dimethylarginine as a serologic marker for kidney function in striped skunks (Mephitis mephitis)

IMPORTANCE

Kidney disease is prevalent among veterinary species, including zoo animals; however, investigations into this condition in striped skunks (Mephitis mephitis) are scarce. Diagnostic tools for kidney diseases in this species also remain limited.

OBJECTIVE

This study aimed to assess the utility of symmetric dimethylarginine as a biomarker for kidney disease in captive striped skunks in Korea.

METHODS

This retrospective study analysed 11 striped skunks housed at the Everland Zoo between 2017 and 2021. Blood samples were collected during health checks. Kidney function was assessed through blood analysis and diagnostic ultrasound, with necropsies conducted on deceased animals. Symmetric dimethylarginine levels were measured in 27 plasma samples collected from 11 skunks.

RESULTS

Over the study period, seven skunks were diagnosed with kidney disease. Analysis of 27 blood samples revealed a concurrent increase in SDMA levels with concentrations of blood urea nitrogen and blood creatinine. In 3 of the 7 skunks with kidney disease, symmetric dimethylarginine exceeded 14 µg/dL prior to the elevation of blood urea nitrogen and blood creatinine above the upper reference limit.

CONCLUSIONS AND RELEVANCE

To our knowledge, this is the first study investigating symmetric dimethylarginine in captive striped skunks in Korea. Our findings suggest that symmetric dimethylarginine may serve as an early and consistent biomarker for renal dysfunction in striped skunks. Further studies with larger clinical sample size from striped skunks are needed to validate the clinical utility of blood symmetric dimethylarginine concentration.

Description of serum symmetric dimethylarginine concentration and of urinary SDS-AGE pattern in dogs with ACTH dependent hyperadrenocorticism

Serum symmetric dimethylarginine (SDMA) and patterns of urinary protein separated by sodium dodecyl sulfate agarose gel electrophoresis (SDS-AGE) have not been investigated as biomarkers in dogs with ACTH-dependent hyperadrenocorticism (ADHAC). This exploratory prospective study aimed to evaluate SDMA, serum creatinine (sCR), and SDS-AGE in dogs with ADHAC with and without proteinuria (ADHAC-P and ADHAC-nP, respectively). Thirty-five pet dogs classified as ADHAC-P (n=16), ADHAC-nP (n=6) and healthy (n=13) were included. Renal biomarkers were evaluated in all dogs at diagnosis. Baseline concentration of SDMA was not significantly different between the three groups (P = 0.15) whereas sCr was significantly lower in dogs in ADHAC dogs compared to healthy dogs (88.0 µmol/L [70.4-132.6; 79.2-114.4]) whether they had proteinuria or not (P = 0.014 and 0.002, respectively). However, baseline concentrations of sCr and SDMA were not significantly different between dogs with ADHAC-P dogs (SDMA, 8 µg/dL [5-12; 7-9]; sCr, 57.2 µmol/L [35.2-212.2; 52.8-92.4]) and ADHAC-nP dogs (SDMA, 8.5 µg/dL [7-13; 8-10]; sCr, 70.4 µmol/L [61.6-79.2; 61.6-70.4]) (P = 0.35 and P = 0.41, respectively). Proteinuria in dogs with ADHAC-P was mainly of glomerular origin (SDS-AGE pattern: glomerular in 10/16 dogs; mixed glomerular/tubular in four dogs). In our study, SDMA was neither significantly different in dogs with ADHAC whether they were proteinuric or not, nor between ADHAC and healthy dogs. Urinary electrophoresis provides additional information to the UPC and further investigations are needed to determine whether it may help identify dogs with ADHAC-P requiring specific antiproteinuric treatment.

Quantitative studies on B-mode ultrasound and point shear wave elastography of kidneys in nonazotemic dogs

Renal diseases in dogs can be diagnosed effectively using B-mode ultrasound. Point shear wave elastography (pSWE) has demonstrated usefulness in diagnosing renal diseases in human medicine. However, its application in veterinary medicine is in its nascent stage. It was hypothesized that establishing pSWE reference values in nonazotemic dogs would prove valuable in differentiating renal diseases. In light of this, a single-center, quantitative study with an objective to normalize B-mode ultrasound parameters and pSWE values of the kidney in nonazotemic dogs was conducted. A total of 198 animals presented with clinical signs of anorexia, vomiting, weight loss, and dehydration were enrolled in the study spanning 2 years. Among them, 52 nonazotemic dogs were included as subjects for the study. B-mode ultrasound quantitative parameters, including length (L), breadth (B), height (H), cortical thickness (RCT), and medulla thickness (RMT) of the kidneys, as well as the diameter of the aorta (Ao), were normalized. Additionally, calculated parameters such as L:Ao, B:Ao, H:Ao, RCT:Ao, and corticomedullary ratios were worked out. Point shear wave elastography values were obtained from the cranial and caudal poles of renal cortices using ElastPQ stiffness software. The pSWE values of kidneys in nonazotemic dogs were normalized. The mean ± standard error values were 1.04 ± 0.08 m/s (95% confidence interval: 0.88-1.19 m/s) and 4.18 ± 0.62 kPa (95% confidence interval: 2.93-5.42 kPa). In conclusion, B-mode ultrasound quantitative parameters, ratios, and pSWE values were normalized in nonazotemic dogs, which may prove valuable in differentiating renal pathologies in canine patients.

A Pilot Study of the Role of Selected Biomarkers of Kidney Injury in Dogs with Dilated Cardiomyopathy

Heart and kidney diseases are among the most frequent medical conditions diagnosed in small animals. Due to the functional interconnection between these organs, the concept of the cardio-renal axis has been developed. In this context, renal disease or dysfunction often occurs secondary to heart diseases, such as dilated cardiomyopathy (DCM). DCM is the most common cardiomyopathy and a leading cause of mortality in large-breed dogs. Traditional biomarkers like creatinine or symmetric dimethylarginine concentration are not always effective, especially in the early stages of the disease, underscoring the need for more sensitive markers of renal impairment during heart failure (HF). This study aimed to evaluate the efficacy of selected biomarkers as indicators for early kidney damage in dogs with stage B2 DCM. We measured serum concentrations of cystatin C, KIM-1 (kidney injury molecule-1), and NGAL (neutrophil gelatinase-associated lipocalin) and their ratios to creatinine, analyzing their diagnostic values. Cystatin C was quantified using a sandwich enzyme immunoassay, while KIM-1 and NGAL were measured with enzyme-linked immunosorbent assay kits designed for canine diagnostics. The concentrations were indexed against serum creatinine. The study included 26 dogs: 9 with HF and 17 healthy controls. The mean ± standard deviation for healthy dogs for cystatin C, cystatin C/creatinine ratio, KIM-1, KIM-1/creatinine ratio, NGAL, and NGAL/creatinine ratio were 0.24 ± 0.04, 0.26 ± 0.07, 0.61 ± 0.07, 0.67 ± 0.13, 2.76 ± 1.8, and 2.79 ± 1.81, respectively. For DCM dogs, these values were 0.27 ± 0.1, 0.32 ± 0.12, 0.61 ± 0.08, 0.69 ± 0.17, 6.46 ± 5.22 (p = 0.02), and 7.99 ± 6.53 (p = 0.04). This study's findings suggest that during the asymptomatic phase of DCM, only NGAL concentration and the NGAL/creatinine ratio may serve as diagnostic markers for early-stage kidney injury.

Symmetric dimethylarginine correlates with the urea, creatinine, potassium, and clinical scores in feline urethral obstructions

BACKGROUND

A urethral obstruction (UO) is an emergency commonly observed in male cats, which can result in significant clinical and laboratory alterations, leading to complications and death.

OBJECTIVES

This study aimed to correlate symmetric dimethylarginine (SDMA) with the urea, creatinine, potassium, and bicarbonate levels in cats with UO. In addition, the correlation between clinical score and time of obstruction was evaluated.

METHODS

Thirty male cats were selected and allocated into a control group (CG, n = 13) and an obstruction group (OG, n = 17). The laboratory analyses were conducted before treatment (M0) and at different times after treatment (12 h [M12], 24 h [M24], and 48 h [M48]). Correlations were established between SDMA and creatinine, urea, bicarbonate, potassium, time of obstruction, and the clinical score.

RESULTS

A strong correlation (r > 0.6) was observed between SDMA and creatinine, urea, and potassium in the OG. Furthermore, there was substantial agreement (kappa value) between SDMA and creatinine at M24. A higher clinical score was associated with a longer time of obstruction. In the OG, at M48, the SDMA and creatinine levels were 50% and 41.2% higher, respectively.

CONCLUSIONS

A correlation was observed between SDMA and creatinine in obstructed cats, and significant agreement between these values was observed 24 h after the unblocking treatment. A correlation among SDMA, urea, and potassium was observed. Approximately 9% more cats continued to have elevated SDMA levels after 48 h of treatment compared to creatinine. This suggests a slightly lower sensitivity of the latter biomarker but does not exclude the possibility of congruent and normalized values after a longer evaluation period.

Serum symmetric dimethylarginine in older dogs: Reference interval and comparison of a gold standard method with the ELISA

BACKGROUND

Serum symmetric dimethylarginine (SDMA) is used to screen for renal dysfunction in dogs. The gold standard technique for measuring SDMA, liquid chromatography-tandem mass spectrometry (LC-MS/MS) is not widely available. Age-specific reference intervals for SDMA in older dogs are lacking.

OBJECTIVES

Prospective study in older dogs to validate a commercially available LC-MS/MS method for SDMA, compare SDMA concentrations with concentrations measured using ELISA and obtain a reference interval (RI) for older dogs using both methods.

ANIMALS

Client-owned older dogs undergoing health screening.

METHODS

The LC-MS/MS method was analytically validated (limit of detection, precision, and linearity). Serum was sent cooled overnight for ELISA or was frozen at -80°C until batch analysis using LC-MS/MS. Results of LC-MS/MS and ELISA were compared and RIs for older dogs were calculated according to international guidelines.

RESULTS

The LC-MS/MS method showed good linearity (r2  = .99) and precision (coefficient of variation <10%), with a laboratory RI between 8.0 and 14.0 μg/dL. Paired measurements were available from 118 different dogs. Median SDMA concentration were 9.4 (range, 5.0-21.2) using LC-MS/MS and 12.0 (range, 5.0-22.0) μg/dL using ELISA. Both methods significantly differed with a mean difference of 2.2 μg/dL. The RI for older dogs for LC-MS/MS was 4.4-15.0 μg/dL, and for ELISA was 6.4-17.4 μg/dL.

CONCLUSIONS AND CLINICAL IMPORTANCE

The ELISA provided significantly higher SDMA concentrations compared to the validated LC-MS/MS method, indicating the need for device- or assay-specific RI. The obtained age-specific RI for SDMA is considerably higher in older dogs compared to the general laboratory RI.

Bilateral neoureterocystostomy with distal ureteral tapering in a dog with severe bilateral hydroureteronephrosis

A 3.5-year-old intact male Labrador retriever was seen for hematuria. The results of clinical pathology tests were unremarkable. However, urinalysis revealed dark, cloudy, alkalotic, and isosthenuric urine containing red and white blood cells, epithelial cells, and struvite crystals. Severe bilateral enlargement of ureters and markedly enlarged kidneys were identified on abdominal radiographs. Computerized tomography revealed extensive bilateral hydroureteronephrosis with no definitive cause of obstruction. The dog underwent bilateral ureteral tapering with bilateral neoureterocystostomy and placement of temporary bilateral ureteral stents and a cystostomy tube. The dog was monitored in the intensive care unit for 7 d after surgery and was discharged 9 d after surgery and after the stent and cystostomy tube were removed. The dog remained clinically normal and was reported to have been euthanized at 11 y of age (2021) due to unspecified causes. Key clinical message: There are several potential causes of severe bilateral hydroureteronephrosis in animals. Based on this case report, dogs with severe bilateral hydroureteronephrosis that are clinically asymptomatic may have favorable outcomes following bilateral ureteral reconstruction and neoureterocystostomy, even if a definitive cause is not identified.

Novel renal injury markers in dogs with ehrlichiosis

Canine monocytic ehrlichiosis (CME) has been observed to impact renal function. Currently, the recognition of acute kidney injury is through the nonspecific biomarker serum creatinine (sCr). Novel markers of renal injury such as urinary clusterin (uClust) and urinary cystatin B (uCysB) may increase our understanding of the relationship between ehrlichiosis and renal cellular injury. The aim of this study was to evaluate novel renal injury biomarkers in dogs with acute CME. Twenty healthy dogs were enrolled in the control group (CG), and 16 dogs naturally infected with Ehrlichia canis were included in the Ehrlichia Group (EG). All dogs were followed for 45 days. EG dogs were treated with doxycycline twice daily for the first 30 days. Urine and serum were collected at: 0, 0.5, 1, 15, 30, and 45 days after start of treatment. Urine concentrations of uClust and uCysB were determined using a research ELISA immunoassay. A linear mixed model was used to estimate population mean of renal injury markers with patient as the random effect, and day and treatment as fixed effects. EG was observed to have higher uClust values compared to CG (estimated population mean EG: 213 ng/dL vs. CG: 84 ng/dL, P < 0.001). EG was observed to have higher uCysB values compared to CG (estimated population mean EG: 248 ng/dL vs. CG: 38 ng/dL, P < 0.001). Increases in uCysB and uClust suggest the presence of renal injury and a possible mechanism for the observed predisposition to chronic kidney disease in dogs with ehrlichiosis.

Use of physical examination, electrocardiography, radiography, and biomarkers to predict echocardiographic stage B2 myxomatous mitral valve disease in preclinical Cavalier King Charles Spaniels

INTRODUCTION

Cavalier King Charles Spaniels (CKCS) are predisposed to developing myxomatous mitral valve disease (MMVD). Dogs with stage B2 MMVD benefit from medication.

OBJECTIVES

To develop (1) breed-specific cut-offs for individual screening tests and (2) predictive models utilizing physical examination (PE), ECG, radiograph, and blood-based biomarker variables in combination for identification of echocardiographic stage B2 MMVD in preclinical CKCS.

ANIMALS

Adult, preclinical CKCS not receiving cardiac medications (N = 226).

MATERIALS AND METHODS

Prospective, cross-sectional study. Enrolled CKCS underwent PE, ECG, radiography, Doppler blood pressure measurement, echocardiography, and biomarker testing. Dogs were grouped by MMVD stage using echocardiography only. The discriminatory ability of individual tests to identify stage B2 was assessed, and prediction models were developed using variables derived from four 'tests' (PE, ECG, radiography, and biomarkers).

RESULTS

N-terminal pro-B-type natriuretic peptide (NT-proBNP) and radiographic vertebral heart size (VHS) had the best discriminatory ability of individual diagnostic tests to differentiate stage A/B1 CKCS from stage B2, with an area under the curve (AUC) of 0.855 and 0.843, respectively. An NT-proBNP ≥1138 pmol/L or a VHS ≥11.5 had high specificity for predicting stage B2 (90.1% and 90.6%, respectively). Prediction models incorporating variables from multiple tests had better discriminatory ability than single tests. The four-test prediction model had an AUC of 0.971. Three and two-test models had AUCs ranging between 0.925-0.959 and 0.895-0.949, respectively.

CONCLUSIONS

Both NT-proBNP and VHS have good utility for predicting echocardiographic stage B2 MMVD in CKCS as individual tests. Prediction models incorporating multiple test variables have superior discriminatory ability.

Differentiation of stable kidney function versus progressive dysfunction in dogs

BACKGROUND

Circulating creatinine and symmetric dimethylarginine (SDMA) are biomarkers of kidney function that have been used variously to define stable vs progressive chronic kidney disease (CKD). Slope monitoring of inverse biomarker values (creatinine-1 or SDMA-1 ) has shown promise, but quantitative criteria to distinguish stable vs progressive CKD using this approach are lacking.

OBJECTIVE

Assessment of creatinine-1 and SDMA-1 slope cutoffs to distinguish stable vs progressive CKD.

ANIMALS

One hundred ten clinically healthy university staff-owned dogs and 29 male colony dogs with progressive X-linked hereditary nephropathy (XLHN).

METHODS

Retrospective analysis combining 2 prospective observational studies, 1 tracking kidney function biomarkers in healthy dogs (HDs) to a maximum of 3 years, and 1 tracking kidney function biomarkers in male colony dogs with progressive XLHN to a maximum of 1 year. The minimum slope of creatinine-1 or SDMA-1 as measured using the IDEXX SDMA test from HD was assigned as the slope cutoff for stable kidney function.

RESULTS

The stable vs progressive slope cutoff was -0.0119 week × dL/mg for creatinine-1 and -0.0007 week × dL/μg for SDMA-1 .

CONCLUSIONS AND CLINICAL IMPORTANCE

In the studied CKD population, progressive dysfunction can be distinguished from stable kidney function by using the slope of creatinine-1 or SDMA-1 . These criteria may serve to characterize CKD in other cohorts of dogs and to establish guidelines for degrees of progression rate in dogs with naturally occurring CKD.

Diagnostic assessment of two-dimensional shear wave elastography in relation to dimethyl arginine levels in dogs with chronic kidney disease

BACKGROUND

In veterinary medicine, previous studies regarding the diagnostic performance of shear wave elastography (SWE) in chronic kidney disease (CKD) are not consistent with each other. Moreover, there has been no study evaluating the relationship between symmetric dimethyl arginine (SDMA) concentration and renal shear wave velocity (SWV) using two-dimensional SWE (2D SWE) in dogs with CKD.

OBJECTIVES

This study aimed to evaluate the diagnostic capability of 2D SWE in dogs with CKD and to assess the relationship between renal SWV and SDMA concentration.

METHODS

Dogs with healthy kidneys and dogs with CKD underwent 2D SWE and SDMA assay. Renal stiffness was estimated as renal SWV in m/s.

RESULTS

SDMA concentration had a weak positive correlation with the left (r = 0.338, p = 0.022) and right renal SWV (r = 0.337, p = 0.044). Renal SWV was not significantly different between healthy kidney and CKD groups in the left (p = 0.085) and right (p = 0.171) kidneys.

CONCLUSIONS

2D SWE may could not distinguish between dogs with healthy kidney and dogs with early stage of CKD, but it would be useful for assessing the serial change of renal function in dogs.

Urinary cystatin B differentiates progressive versus stable IRIS Stage 1 chronic kidney disease in dogs

BACKGROUND

Early identification of dogs with progressive vs stable chronic kidney disease (CKD) might afford opportunity for interventions that would slow progression. However, currently no surrogate biomarker reliably predicts CKD progression.

HYPOTHESIS/OBJECTIVES

Urinary cystatin B (uCysB), a novel kidney injury biomarker, predicts progressive disease in International Renal Interest Society (IRIS) CKD Stage 1.

ANIMALS

Seventy-two dogs, including 20 dogs from 4 university centers with IRIS CKD Stage 1, with IDEXX symmetric dimethylarginine (SDMA) concentration up to 17 μg/dL and no systemic comorbidities, and 52 clinically healthy staff-owned dogs from a fifth university center.

METHODS

A multicenter prospective longitudinal study was conducted between 2016 and 2021 to assess uCysB concentration in IRIS CKD Stage 1 and control dogs. Dogs were followed to a maximum of 3 years (control) or 25 months (CKD). Stage 1 IRIS CKD was classified as stable or progressive using the slope of 1/SDMA, calculated from 3 timepoints during the initial 90-day period. Dogs with slope above or below -0.0007 week × dL/μg were classified as stable or progressive, respectively. Mixed effects modeling was used to assess the association between uCysB and progression rate.

RESULTS

Estimates of first visit uCysB results predictive of active ongoing kidney injury based on the mixed effects models were 17 ng/mL for control, 24 ng/mL for stable CKD, and 212 ng/mL for progressive CKD (P < .001).

CONCLUSIONS AND CLINICAL IMPORTANCE

Urinary cystatin B differentiated stable vs progressive IRIS CKD Stage 1. Identification of dogs with progressive CKD may provide an opportunity for clinicians to intervene early and slow progression rate.

Association between Hyperglycemia and Canine Serum Pancreatic Lipase Immunoreactivity Concentration in Diabetic Dogs

It has been reported that hypertriglyceridemia can partially mediate between diabetes mellitus (DM) and pancreatitis in dogs, implying that another mediator, such as chronic hyperglycemia, might exist. Therefore, this study aimed to evaluate the relationship between hyperglycemia and serum canine pancreatic lipase immunoreactivity (cPLI) concentration in diabetic dogs. This retrospective cohort study included 26 client-owned diabetic dogs, divided according to their serum fructosamine levels (<500 μmol/L = well-controlled DM group; ≥500 μmol/L = untreated or poorly controlled DM group). Five of the 26 DM dogs (19.2%) had serum cPLI concentrations consistent with pancreatitis, among which two showed ultrasonographic evidence of pancreatitis without clinical signs. The serum cPLI concentrations (median [interquartile range]) were significantly higher in the untreated or poorly controlled group (520 μg/L [179.76-1000 μg/L]) than in the well-controlled group (77 μg/L [32.22-244.6 μg/L], P = 0.0147). The serum fructosamine concentration was positively correlated with the serum cPLI concentration (r = 0.4816; P = 0.0127). Multivariate analysis revealed serum triglyceride and fructosamine concentrations were associated with the serum cPLI concentration. In conclusion, this study suggests that chronic hyperglycemia may induce pancreatic inflammation in diabetic dogs; however, the clinical significance of increased cPLI concentration is unknown.

Effect of storage temperature and time on measurement of serum symmetric dimethylarginine concentration using point-of-care and commercial laboratory analyzers in cats and dogs

BACKGROUND

Stability of serum symmetric dimethylarginine (sSDMA) during short- and long-term storage has not been assessed for the immunoassay of the Point-of-Care IDEXX Catalyst DX (POC) analyzer and the Enzyme Multiplied Immunoassay Technique of IDEXX commercial laboratory (CL). Also, the agreement between both analyzers is questioned.

OBJECTIVES

To determine (a) the effect of storage time and temperature on sSDMA measured by POC and CL; (b) the agreement between sSDMA measured by POC and CL; and (c) the imprecision of the POC.

ANIMALS

Serum of cats (n = 17) and dogs (n = 18) with a range of SDMA concentrations (6 to >100 μg/dL).

METHODS

Based on an equivalence trial with predefined equivalence range (-3.0 to +3.0 μg/dL) and using T0 as baseline, stability was evaluated after 24 hours at 22°C and 4°C (POC); after 7 days at 4°C (POC and CL) and after 10 and 24 months at -24°C and -80°C (CL). Bland-Altman plots enabled method comparison. Imprecision of the POC was assessed by duplicate sSDMA measurements at T0.

RESULTS

The POC analyzer produced equivalent sSDMA measurements if samples were stored for 24 hours at 4°C (95% confidence interval [CI]: -2.5-2.0 μg/dL), but not when stored for 24 hours at room temperature (RT; 95% CI: -4.1 to 0.5 μg/dL) or after 7 days at 4°C (95% CI: -3.6-1.0 μg/dL). The CL analyzer was less affected by preanalytical variation with clinically similar results obtained when samples were stored for 7 days at 4°C (95% CI: -2.2 to 2.4 μg/dL) and for at least 24 months at -24°C (95% CI: -1.7 to 2.9 μg/dL) and -80°C (95% CI: -1.5 to 3 μg/dL). A relevant mean difference of -2.3 μg/dL between both analyzers was found. Duplicate POC measurements were equivalent (95% CI: -2.6 to 2.0 μg/dL).

CONCLUSIONS

Delayed analysis may significantly change sSDMA depending on storage and measurement conditions. Interchangeable use of assays should be done with caution because analytical variation could be interpreted as clinically relevant change.

PRELIMINARY EVALUATION OF SYMMETRIC DIMETHYLARGININE AS A BIOMARKER OF RENAL INSUFFICIENCY IN WILD AND REHABILITATED FLORIDA MANATEES (TRICHECHUS MANATUS LATIROSTRIS)

Currently, there are limited antemortem tests available to evaluate renal function in Florida manatees (Trichechus manatus latirostris). Although few reports of renal pathology in manatees exist in the veterinary literature, debilitated animals that present to rehabilitation centers are frequently dehydrated, may have sustained renal trauma secondary to watercraft injury, and may experience ischemic events related to coagulation disorders leading to renal compromise. Clinicians remain limited to the analysis of blood urea nitrogen, creatinine levels, and urinalysis (if urine is obtained) to determine the extent of renal insufficiency, which may not accurately reflect renal function. This poses a diagnostic challenge for clinicians in discerning how critical renal compromise is to the animal's overall health and prognosis. For the first phase of this study, retrospective symmetric dimethylarginine (SDMA) values were determined from banked serum or plasma samples from 14 wild Florida manatees that had been collected while the animals were under rehabilitation in zoological institutions prior to their deaths. Values of SDMA for nine samples from eight manatees with known renal disease, as determined by histopathology, were compared to SDMA values for seven samples from six manatees with no reported renal lesions on histopathology. Values of SDMA from wild Florida manatees with known renal disease (mean 33.56 µg/dl ± 13.15, P= 0.017) were statistically significantly elevated when compared to SDMA values from manatees with no reported renal lesions (mean = 18.71 µg/dl ± 6.9) on histopathology. For the second phase of the study, serum or plasma samples were obtained from wild manatee populations from two geographically separate presumed-healthy wild manatee populations (n = 57). Although the upper limit was higher, serum SDMA concentrations from presumed-healthy wild manatees were comparable to those reported in small animal and equine medicine at 5.88-16.97 µg/dl.

Evaluation of renal values during treatment for heartworm disease in 27 client-owned dogs

BACKGROUND

Canine heartworm disease (CHD) caused by Dirofilaria immitis remains a common preventable disease with increasing incidence in some parts of the USA. The treatment guidelines of the American Heartworm Society (AHS) currently recommend monthly macrocyclic lactone administration, 28 days of doxycycline given orally every 12 h and three injections of melarsomine dihydrochloride (1 injection on day 2 of treatment followed 30 days later by 2 injections 24 h apart). Minocycline has also been utilized when doxycycline is unavailable. The systemic effects of CHD, which particularly impact cardiac and renal function, have been described, with infected dogs often experiencing renal damage characterized by an increase in serum concentrations of renal biomarkers. Although the AHS treatment protocol for CHD has been shown to be safe and effective in most cases, the potential for complications remains. No study as of yet has evaluated changes in symmetric dimethylarginine (SDMA), a sensitive marker of renal function, during treatment for CHD. The purpose of the present study was to evaluate renal function in dogs by measuring serum creatinine and SDMA concentrations during the adulticide treatment period.

METHODS

Serum creatinine and SDMA concentrations were measured in 27 client-owned dogs affected by CHD at the following time points: prior to starting doxycycline or minocycline therapy (baseline), during doxycycline or minocycline therapy (interim), at the time of the first dose of melarsomine (first dose), at the time of the second dose of melarsomine (second dose) and at the dog's follow-up visit after treatment, occurring between 1 and 6 months after completion of therapy (post-treatment). Concentrations of creatinine and SDMA were compared between time points using a mixed effects linear model.

RESULTS

Mean SDMA concentrations following the second dose of melarsomine were significantly lower (-1.80 ug/dL, t-test, df = 99.067, t = -2.694, P-Value = 0.00829) than baseline concentrations. There were no other statistically significant differences in the concentration of either biomarker between the baseline and the other time points in CHD dogs undergoing treatment.

CONCLUSIONS

The results suggest that the current AHS protocol may not have a substantial impact on renal function.

Urinary cystatin C and N-acetyl-beta-D-glucosaminidase (NAG) as early biomarkers for renal disease in dogs with leishmaniosis

Canine leishmaniasis (CanL) is a disease caused by Leishmania infantum that can vary from a subclinical infection to a severe disease. Dogs affected with CanL present varying degrees of renal dysfunction. Unfortunately, traditional biomarkers such as urea and creatinine detect renal damage in advanced stages of the disease, so more accurate biomarkers are needed. Hence, we aimed to study how urinary cystatin C (CysC) and N-acetyl-beta-D-glucosaminidase (NAG), behave in dogs with CanL at different stages of the disease. Eighty-six CanL infected dogs were classified according to LeishVet stages: LI (16 dogs), LIIa (12 dogs), LIIb (12 dogs), LIII (16 dogs) and LIV (30 dogs); as a control, 17 healthy dogs were studied. Blood samples were collected for complete haematological and biochemistry analysis including plasma cystatin C. Urine analysis included urine specific gravity (USG), urine protein to creatinine ratio (UPC), CysC and NAG expressed as a ratio with creatinine uCysCc (μg/g) and uNAGc (IU/g). The haematological, biochemical and urinary analysis coincided with the LeishVet guidelines. The statistical study of the uCysCc ratio and the uNAGc, showed significant increase when compared against control starting from group LI (p < 0.05). Interestingly, when the cut-off values were calculated using the ROC curve, uCysCc (258.85 µg/g) and uNAGc (2.25 IU/g) 75 % of the dogs included in LI groups surpassed the threshold. Hence our study indicates that uCysCc and uNAGc, could help to detect early renal damage in CanL affected dogs.

Effects of Mouse Kidney Parvovirus on Pharmacokinetics of Chemotherapeutics and the Adenine Model of Chronic Kidney Disease

Mouse kidney parvovirus (MKPV) causes inclusion body nephropathy in severely immunocompromised mice and renal interstitial inflammation in immunocompetent mice. Here we sought to determine the effects of MKPV on pre-clinical murine models that depend on renal function. To assess the effects of MKPV infection on the pharmacokinetics of 2 renally excreted chemotherapeutic agents, methotrexate and lenalidomide, we measured drug concentrations in the blood and urine of MKPV-infected or uninfected immunodeficient NOD.Cg-PrkdcscidIl2rgtm1Wjl/SzJ (NSG) and immunocompetent C57BL/6NCrl (B6) female mice. No differences in plasma pharmacokinetics were observed for lenalidomide. However, the AUC of methotrexate was 1.5-fold higher in uninfected NSG mice compared with infected NSG mice, 1.9-fold higher in infected B6 mice compared with uninfected B6 mice, and 4.3-fold higher in uninfected NSG mice compared with uninfected B6 mice. MKPV infection did not significantly affect the renal clearance of either drug. To assess effects of MKPV infection on the adenine diet model of chronic kidney disease, MKPV-infected and uninfected B6 female mice were fed a 0.2% adenine diet, and clinical and histopathologic features of disease were assessed over 8 wk. MKPV infection did not significantly alter urine chemistry results, hemogram findings, or serum concentrations of BUN, creatinine, or symmetric dimethylarginine. However, infection did influence histologic outcomes. As compared with uninfected mice, MKPV-infected mice had more interstitial lymphoplasmacytic infiltrates after 4 and 8 wk of diet consumption and less interstitial fibrosis at week 8. Macrophage infiltrates and renal tubular injury were similar between in infected and uninfected mice. These findings indicate that MKPV infection had minimal effects on the renal excretion of 2 chemotherapeutics and on serum biomarkers of renal function. However, infection significantly influenced two histologic features of the adenine diet model of chronic renal disease. MKPV-free mice are critically important in studies evaluating renal histology as an experimental outcome.

Arginine, symmetric and asymmetric dimethylarginine levels in canine leishmaniasis

The study aimed to investigate the levels of arginine, symmetric dimethylarginine (SDMA), and asymmetric dimethylarginine (ADMA) in dogs with canine leishmaniasis (CanL) and their relationship with some renal and cardiovascular parameters. A total of 60 dogs were enrolled, including 40 with CanL and 20 healthy controls. The CanL group was divided into four stages based on clinical and laboratory findings. The levels of plasma arginine, SDMA, and ADMA were determined by high performance liquid chromatography (HPLC). The data from the healthy group were compared with those from the CanL group, and according to the stages. In dogs with CanL, systolic and diastolic blood pressure, plasma creatinine, cystatin-C, phosphorus, potassium, and low-density lipoprotein concentrations, the urine protein/creatinine ratio, the amount of nitric oxide, and creatine kinase-MB activity were higher, while the high-density lipoprotein concentration was lower compared to healthy controls. The concentration of arginine was low (p < 0.05) and the levels of ADMA (p < 0.001) and SDMA (p < 0.05) were high in dogs with CanL. There were no statistically significant differences in arginine concentration among the different stages of CanL. However, the concentration of plasma ADMA was higher in all stages of CanL compared to the healthy group, and the concentration of plasma SDMA was higher in Stage IV compared to the healthy group and Stage III. The present study demonstrates for the first time a decrease in arginine concentration and an increase in ADMA concentration in dogs with CanL. The increase in SDMA concentration in dogs with CanL was consistent with previous studies. However, compared to other renal parameters, SDMA exhibited limited performance distinguishing between clinical stages of CanL. These findings could be a source for future diagnostic and therapeutic studies to explain the renal and cardiovascular pathophysiology of CanL. Additional clinical studies that include treatment and patient follow-up with an assessment of the acute phase response are needed to provide a more detailed understanding of the changes observed in dogs with CanL.

EVALUATION OF SYMMETRIC DIMETHYLARGININE AS AN ENDOGENOUS MARKER OF RENAL DISEASE IN GREATER FLAMINGOS (PHOENICOPTERUS ROSEUS)

Detection of renal disease in birds is currently reliant on biochemical measures such as uric acid, which is only elevated after significant renal compromise has occurred. Symmetric dimethylarginine (SDMA) production has not been previously evaluated in birds and no reference intervals (RI) for measurement exist in avian species. This study aimed to develop an RI for SDMA in greater flamingos (Phoenicopterus roseus) and evaluate the association between SDMA levels and renal disease. Blood from 60 flamingos was collected for RI development and the RI of SDMA was found to be 11.8-34.2 µg/dl. Symmetric dimethylarginine showed a strong positive correlation with uric acid, a moderate positive correlation with creatine kinase, and moderate negative correlations with total protein, albumin, and glucose. No correlation was found with pododermatitis score or body condition. Using the SDMA RI, six clinical cases were included for assessment of the clinical relevance of SDMA in renally compromised patients. All birds that were euthanized had elevated SDMA levels and severe renal or systemic pathology on necropsy.

Outcome of Acquired Fanconi Syndrome Associated with Ingestion of Jerky Treats in 30 Dogs

Acquired canine proximal renal tubulopathy (Fanconi syndrome) related to excessive ingestion of jerky treats has been recognized since 2007. This study aimed to improve knowledge about the syndrome’s characteristics, especially long-term outcome. By reaching out to veterinarians and dog owners, dogs suspected of jerky induced Fanconi syndrome were identified. The dog’s medical records were reviewed, and owners interviewed. Data was analyzed using linear mixed models (p < 0.05 was considered statistically significant) and descriptive statistics are reported. Thirty dogs, median body weight 6.8 (range 1.2−59) kg and age 6.5 (0.5−14) years, were enrolled as suspected cases based on history of jerkey ingestion and confirmed normoglycemic/hypoglycemic glycosuria. Clinical signs included polydipsia (23/30), polyuria (21/30), lethargy (19/30), weight loss (15/30), hyporexia (11/30), vomiting (7/30), diarrhea (7/30) and no clinical signs (2/30). Para-clinical findings included azotemia (6/28), hypophosphatemia (9/25), metabolic acidosis (3/8), hypokalemia (6/20), proteinuria (13/26), aminoaciduria (4/4), hematuria (22/29) and ketonuria (7/27). Clinical signs resolved in 22/28 within 11 (0.3−52) weeks and glycosuria resolved in 28/30 within 6.5 (1−31) weeks. There were no associations between serum creatinine and urea and the amount/duration of jerky ingestion. Serum symmetric dimethylarginine concentrations were only available for a few dogs, therefore no conclusion was achieved on a possible association with duration of jerky ingestion. Apart from a larger percentage of dogs achieving complete recovery, the current findings are in agreement with previous reports.

Serum uromodulin in dogs with chronic kidney disease

BACKGROUND

Serum uromodulin concentration has been described as a novel biomarker of chronic kidney disease (CKD) in humans but not dogs.

OBJECTIVE

To evaluate the serum uromodulin concentration in dogs with CKD and assess its diagnostic performance in distinguishing dogs with CKD from healthy dogs.

ANIMALS

Forty-nine dogs with CKD (International Renal Interest Society [IRIS] Stage 1, n = 23; Stage 2, n = 20; Stage 3-4, n = 6) and 25 healthy controls.

METHODS

Prospective, observational study. Serum uromodulin concentration was measured using a canine-specific enzyme-linked immunosorbent assay (ELISA), and its correlation with conventional renal markers was analyzed.

RESULTS

Serum uromodulin concentrations were significantly lower in the CKD group than in the control group (P < .001), but no significant difference was observed among stages of CKD. A negative correlation was observed between serum uromodulin concentration and conventional renal markers (blood urea nitrogen concentration, r = -.60, P < .0001; serum creatinine concentration, r = -.46, P < .0001; serum symmetric dimethylarginine concentration [SDMA], r = -.65, P < .0001). In receiver operating characteristic analysis, the area under the curve (AUC) of uromodulin (AUC, 0.97; 95% confidence interval [CI], 0.94-1.00) was higher than that of SDMA (AUC, 0.87; 95% CI, 0.79-0.95) for CKD diagnosis (P = .01). The AUC of uromodulin (AUC, 0.95; 95% CI, 0.89-1.00) also was higher than that of SDMA (AUC, 0.72; 95% CI, 0.58-0.87) in distinguishing dogs with Stage 1 CKD from controls (P = .001).

CONCLUSIONS AND CLINICAL IMPORTANCE

Serum uromodulin concentration is decreased in dogs with CKD. Thus, serum uromodulin may be a valuable diagnostic marker for CKD in dogs, particularly in identifying early-stage CKD.

Efficacy of domperidone plus renal diet in slowing the progression of chronic kidney disease in dogs with leishmaniosis

BACKGROUND

Chronic kidney disease (CKD) represents the main cause of mortality in dogs with leishmaniosis. Domperidone has recently been reported to improve kidney function in leishmaniotic dogs affected by CKD. Serum symmetric dimethylarginine (sSDMA) has also been shown to be a useful biomarker for earlier detection of decreased kidney function when compared to serum creatinine (sCr). This study aimed to assess the efficacy of domperidone plus renal diet in slowing the progression of nephropathy in leishmaniotic dogs with CKD, evaluating sSDMA and sCr as markers of kidney function.

METHODS

This study was a therapeutic, prospective, randomized, controlled, 11-month-long field trial. Dogs were recruited if classified as "exposed" to or "infected" with Leishmania infantum and affected by CKD at early stages. After enrolment (T0), dogs were randomized into groups T (treatment) and C (control). All dogs were fed a renal diet and then followed up at 90 (T1), 210 (T2), and 330 (T3) days after inclusion in the study. At T1 and T2, dogs in group T received an oral suspension of domperidone (1 ml/10 kg once a day for up to 28 days).

RESULTS

Twenty-two dogs (i.e., n = 12 in group T and n = 10 in group C) completed the study. At T0, the entire population of enrolled dogs presented a mean sSDMA value of 16.5 ± 3.4 μg/dl. At T1 (i.e., after 3 months of renal diet), sSDMA was significantly decreased in both groups, with an sSDMA of 13.1 ± 4.4 μg/dl for the entire population involved. From T1 to T3, sSDMA gradually increased in group C, while remaining stable in group T, which continued to show a significantly lower value of sSDMA at T3 than at T0. Regarding sCr, at T0 and T1, the mean values of the entire population of dogs were 1.1 ± 0.3 and 1.0 ± 0.4 mg/dl, respectively, with no statistical differences between groups T and C. In group T, sCr decreased significantly from T0 to T1, while returning at T3 to values similar to T0.

CONCLUSIONS

In this study, domperidone plus renal diet reduced the progression of kidney disease in leishmaniotic dogs affected by CKD.

Assessment of serum symmetric dimethylarginine and creatinine concentrations in cats with urethral obstruction

OBJECTIVES

The aims of this study were to evaluate serum symmetric dimethylarginine (SDMA) and creatinine concentrations in cats with urethral obstruction pre- and post-decompression of the obstruction, and to determine if pre-decompression values were predictive of post-decompression renal function, as measured by SDMA and creatinine.

METHODS

This was a prospective observational study. Twenty-five client-owned cats with urethral obstruction were hospitalized for decompression of the obstruction. Serum SDMA and creatinine were prospectively assessed at presentation, 24 h post-decompression and 5-20 days post-decompression. Urinalysis and culture were assessed at presentation and at the final follow-up. Exclusion criteria included positive urine culture, reobstruction or failure to obtain required samples.

RESULTS

Mean SDMA concentration dropped by 41.8% from an initial pre-decompression concentration of 17.6 µg/dl to 10.3 µg/dl 24 h post-decompression (P <0.001). The mean creatinine value dropped by 38.4% from an initial pre-decompression concentration of 2.5 mg/dl to 1.5 mg/dl 24 h post-decompression (P <0.001). There was no association between SDMA concentration at initial presentation and SDMA concentration 5-20 days after urethral catheterization (Spearman's ρ = 0.205, P = 0.314). Creatinine concentration upon initial presentation was associated with the 5-20 day values after urethral catheterization (Spearman's ρ = 0.583, P <0.002). Twenty percent of cases were excluded due to bacterial growth on initial urine culture. SDMA and creatinine concentrations were significantly higher in these cases (median 59 µg/dl and 10.9 mg/dl, respectively) compared with those with negative cultures (median 14 µg/dl and 1.6 mg/dl [P <0.002 and P <0.001], respectively).

CONCLUSIONS AND RELEVANCE

Both SDMA and creatinine decreased significantly after urethral catheterization, suggesting that renal function post-decompression cannot be predicted by the pre-decompression concentrations of these values.

No adverse consequences associated with targeting clinical signs to initiate antimicrobial treatment of postoperative subclinical bacteriuria in dogs following surgical decompression of Hansen type I thoracolumbar disk herniation

OBJECTIVE

To describe the prevalence of postoperative bacteriuria, clinical course of subclinical bacteriuria in the absence of antimicrobial intervention, clinical signs of bacteriuria that trigger antimicrobial treatment, and outcomes for dogs with subclinical bacteriuria following surgical decompression of acute intervertebral disc herniation (IVDH) Hansen type I.

ANIMALS

Twenty client-owned dogs undergoing hemilaminectomy for acute (≤ 6 days) IVDH Hansen type I affecting the thoracolumbar spinal cord segments between August 2018 and January 2019.

PROCEDURES

In this prospective study, dogs were serially evaluated at presentation, hospital discharge, 2 weeks postoperatively, and between 4 and 6 weeks postoperatively. Dogs were monitored for clinical signs of bacteriuria, underwent laboratory monitoring (CBC, biochemical analyses, urinalysis, urine bacterial culture), and were scored for neurologic and urinary status. In the absence of clinical signs, bacteriuria was not treated with antimicrobials.

RESULTS

Four of the 18 dogs developed bacteriuria without clinical signs 4 days to 4 to 6 weeks after surgery. In all 4 dogs, bacteriuria resulted in lower urinary tract signs 13 to 26 weeks postoperatively. No dogs had evidence of systemic illness despite delaying antimicrobial treatment until clinical signs developed. New-onset incontinence was the only clinical sign in 3 dogs. All bacterial isolates had wide antimicrobial susceptibility. Bacteriuria and clinical signs resolved with beta-lactam antimicrobial treatment.

CLINICAL RELEVANCE

Postoperative bacteriuria occurs in some dogs with IVDH Hansen type I and, when present, may lead to clinical signs over time. Clinical signs of bacteriuria may be limited to new-onset urinary incontinence, inappropriate urination, or both. Delaying antimicrobial treatment until clinical signs of bacteriuria developed did not result in adverse consequences or systemic illness.

Evaluating maternal exposure to an environmental per and polyfluoroalkyl substances (PFAS) mixture during pregnancy: Adverse maternal and fetoplacental effects in a New Zealand White (NZW) rabbit model

Mixtures of per- and polyfluoroalkyl substances (PFAS) are often found in drinking water, and serum PFAS are detected in up to 99% of the population. However, very little is known about how exposure to mixtures of PFAS affects maternal and fetal health. The aim of this study was to investigate maternal, fetal, and placental outcomes after preconceptional and gestational exposure to an environmentally relevant PFAS mixture in a New Zealand White (NZW) rabbit model. Dams were exposed via drinking water to control (no detectable PFAS) or a PFAS mixture for 32 days. This mixture was formulated with PFAS to resemble levels measured in tap water from Pittsboro, NC (10 PFAS compounds; total PFAS load = 758.6 ng/L). Maternal, fetal, and placental outcomes were evaluated at necropsy. Thyroid hormones were measured in maternal serum and kit blood. Placental gene expression was evaluated by RNAseq and qPCR. PFAS exposure resulted in higher body weight (p = 0.01), liver (p = 0.01) and kidney (p = 0.01) weights, blood pressure (p = 0.05), and BUN:CRE ratio (p = 0.04) in dams, along with microscopic changes in renal cortices. Fetal weight, measures, and histopathology were unchanged, but a significant interaction between dose and sex was detected in the fetal: placental weight ratio (p = 0.036). Placental macroscopic changes were present in PFAS-exposed dams. Dam serum showed lower T4 and a higher T3:T4 ratio, although not statistically significant. RNAseq revealed that 11 of the 14 differentially expressed genes (adj. p < 0.1) are involved in placentation or pregnancy complications. In summary, exposure elicited maternal weight gain and signs of hypertension, renal injury, sex-specific changes in placental response, and differential expression of genes involved in placentation and preeclampsia. Importantly, these are the first results to show adverse maternal and placental effects of an environmentally-relevant PFAS mixture in vivo.

Symmetric Dimethylarginine is a Promising Biomarker for the Early Detection of Age-Related Kidney Dysfunction in Zoo Felids

Chronic renal failure is one of the leading causes of death in African lions, cheetahs, and tigers. Conventional methods to measure renal dysfunction include measuring serum creatinine and blood urea nitrogen (BUN). Symmetric dimethylarginine (SDMA) measurement is a reliable predictor of renal dysfunction in the domestic cat because SDMA serum levels increase early when the kidneys are damaged. Serum SDMA levels were assessed and correlated with creatinine as well as BUN from healthy captive Bengal tigers and lions at the Everland Zoo in Korea. Serum SDMA concentrations were increasingly associated with increased age in lions. However, SDMA concentrations were higher in some young Bengal tigers than in older ones, which may allow for earlier renal dysfunction detection in these young cats than would be BUN and creatinine alone. In Bengal tigers, the correlation between the SDMA and BUN was slightly higher than that between SDMA and creatinine. In lions, SDMA correlated better with creatinine than with BUN concentration. These results show that serum SDMA concentration can be used as a biomarker for age-associated renal dysfunction. SDMA measurement may be an essential preventive management method in zoos.

The association between symmetric dimethylarginine concentrations and various neoplasms in dogs and cats

Following the introduction of the symmetric dimethylarginine (SDMA) immunoassay, cases were reported where the SDMA concentration was markedly increased above the reference interval (RI) with neither concurrent increases in serum creatinine (Cr) concentrations nor clinical signs of kidney disease. Many of these animals were also concurrently diagnosed with cancer, most commonly lymphoma. The purpose of the study was to evaluate the association of increased SDMA in dogs and cats with lymphoma and other cancers as compared with age- and breed-matched non-tumour controls. In this retrospective case-control study, serum chemistry results from 1804 tumour cases, and age- and breed-matched non-tumour control animals were used. Matched-pair odds ratios between animals diagnosed with neoplasms and non-tumour controls for dichotomized SDMA values were determined by tumour type. SDMA concentrations were significantly higher in dogs and cats with lymphoma (p < .0001) compared with non-tumour controls. The odds ratio for increased SDMA concentrations in dogs with lymphoma was 10.0 (95% CI, 5.98-16.72) and for cats with lymphoma was 3.04 (95% CI 1.95-4.73). A significant number of canine and feline lymphoma cases had an increased SDMA concentration not associated with an increased Cr concentration (p < .001). Canine and feline lymphoma patients have an increased odds of having a SDMA concentration above the RI at diagnosis. Further characterization and evaluation of dogs and cats with lymphoma is required to help understand the mechanism(s) and the clinical significance of these alterations.

Evaluation of renal injury and function biomarkers, including symmetric dimethylarginine (SDMA), in the rat passive Heymann nephritis (PHN) model

Symmetric dimethylarginine (SDMA) is a serum biomarker of excretory renal function which consistently correlates with glomerular filtration rate (GFR) across multiple species including rats, dogs, and humans. In human and veterinary clinical settings SDMA demonstrates enhanced sensitivity for detection of declining renal function as compared to other serum biomarkers, but application in preclinical study designs thus far has been limited. The purpose of this study was to determine the performance of serum SDMA in a rat passive Heyman nephritis model of glomerulopathy. In addition to SDMA other biomarkers of excretory renal function were measured including serum creatinine (sCr), blood urea nitrogen (BUN), and cystatin C along with creatinine clearance. Urinary renal biomarkers including microalbumin (μALB), clusterin (CLU), cystatin C, kidney injury marker-1 (KIM-1), neutrophil gelatinase-associated lipocalin (NGAL), and osteopontin (OPN) were also measured. PHN was induced using commercial sheep anti-Fx1A serum. Tissue, serum, and urine were collected from groups of control and anti-Fx1A-treated animals for biomarker evaluation, hematology, urinalysis, serum biochemistry, and histologic examination of kidney. Over the course of a 28-day study, concentrations of the urinary biomarkers μALB, CLU, cystatin C, NGAL, KIM-1 and the serum biomarker cystatin C increased significantly in anti-Fx1A-treated rats as compared to controls but no significant increase in serum SDMA, sCr, BUN, or creatinine clearance were noted in anti-Fx1A-treated rats. Given lack of direct GFR measurement or significant change in the renal function biomarkers sCr, BUN, and creatinine clearance, it is unclear if GFR differed significantly between control and anti-Fx1A-treated rats in this study, though urinary biomarkers and histopathologic findings supported renal injury in anti-Fx1A-treated rats over the time course investigated. This study is among the first to investigate serum SDMA in a rat model relevant to preclinical safety assessment and serves to inform future experimental designs and biomarker selection when evaluation of glomerular injury is of priority.

Blood concentration of symmetric dimethylarginine correlates with kidney damage as assessed with a proposed histologic grading system for chronic kidney disease in tigers (Panthera tigris)

OBJECTIVE

To determine the utility of blood symmetric dimethylarginine (SDMA) concentration measurement as a diagnostic tool for chronic kidney disease (CKD) in tigers (Panthera tigris) by comparing results for SDMA with those for traditional renal biomarkers and investigating correlations between these biomarkers and histopathologic kidney changes in tigers with CKD.

SAMPLE

Blood, urine, and kidney samples from 35 tigers with CKD from 2 sanctuaries.

PROCEDURES

Blood (serum or plasma) and urine samples were collected antemortem. Necropsy, including gross and histologic assessment, was performed for tigers that died or were euthanized for quality-of-life reasons. Results for CKD biomarkers in blood (BUN, creatinine, phosphorus, and SDMA concentrations) and urine (protein concentration, urine protein-to-creatinine ratio, and urine specific gravity) were evaluated for correlation with histologic kidney damage scored with an objective grading scale defined by percentage of inflammation, fibrosis, and tubular atrophy.

RESULTS

Symmetric dimethylarginine had the strongest significant correlation (ρ = 0.667) with histologic kidney damage score, followed by urine specific gravity (ρ = -0.639), blood creatinine concentration (ρ = 0.624), and BUN (ρ = 0.588). No significant correlation with kidney score was identified for blood phosphorus concentration, urine protein concentration, or the urine protein-to-creatinine ratio.

CLINICAL RELEVANCE

We recommend SDMA be prioritized as a renal biomarker in tigers, with SDMA results considered in addition to those of other traditional renal biomarkers when assessing kidney function in tigers. Additionally, the grading scale we developed could be replicated across patients and pathologists for more consistent postmortem assessment of CKD in tigers.

Symmetrical Dimethylarginine as a Diagnostic Parameter in Hermann's Tortoises (Testudo hermanni)

Background

Despite improvements in habitational conditions, kidney disease is relatively common in tortoises.

Objectives

Purpose of this study was the establishment of Symmetrical dimethylarginine (SDMA) reference values for clinically healthy Hermann's Tortoises.

Animals

Clinically healthy Hermann's Tortoises (n = 131) were included in the period from October 2017 to September 2019.

Methods

Creatinine and other biomarkers were tested at IDEXX Laboratories, Germany using residual blood samples from Hermann's tortoises. SDMA was measured with the IDEXX test and verified by liquid chromatography-mass spectrometry at IDEXX Laboratories, USA.

Results

SDMA values ranged from 1 to 21 μg/dl (n = 131) for the IDEXX SDMA Test and SDMA values ranged from 1 to 17 μg/dl (n = 82) for LC-MS. For the comparison of the two measuring systems, the following results were obtained R 2 = 0.75 (p < 0.001).

Conclusion and Clinical Importance

SDMA can be measured in Hermann's Tortoises and the reference values range in clinically healthy animals is comparable to that of dogs and cats.

Short course of immune-suppressive doses of prednisolone, evaluated through a prospective double-masked placebo-controlled clinical trial in healthy Beagles, is associated with sustained modifications in renal, hydration, and electrolytic status

OBJECTIVE

To investigate the effects and duration of orally administered prednisolone on renal function evaluated by glomerular filtration rate (GFR) determination and creatinine (Cr) and symmetric dimethylarginine (SDMA) concentrations as well as on urinalysis, electrolytes, and hydric status in healthy dogs.

ANIMALS

14 healthy Beagles.

PROCEDURES

In this prospective double-masked placebo-controlled study, dogs were randomized after baseline evaluation to receive a 7-day course of either prednisolone (1.5 to 2.0 mg/kg, PO, q 12 h) or a placebo. A repeated-measure design was performed, each dog participating in 4 successive sampling sessions. Clinical data, systolic blood pressure, CBC, and biochemical analyses including serum SDMA concentration, GFR determination, urine output quantification, and complete urinalysis were performed for all dogs the day before (D0) and at the end of steroid administration (D7) as well as 2 weeks (D21) and 4 weeks (D35) after the end of treatment.

RESULTS

At D7, when compared with baseline, GFR increased significantly in treated dogs, whereas creatinine and SDMA concentrations decreased significantly. GFR and Cr but not SDMA modifications persisted significantly at D21. None of the variables differed significantly from baseline at D35. The OR of presenting an albumin band on urine electrophoresis was 2.4 times as high in treated versus control dogs (OR, 36; 95% CI, 1.8 to 719.4; P = 0.02).

CLINICAL RELEVANCE

A short-term course of immune-suppressive prednisolone treatment in healthy dogs leads to a sustained but reversible renal hyperfiltration state. Modification in electrolytic variables can affect the clinical interpretation of blood work in such patients.

Drug-Dosing Adjustment in Dogs and Cats with Chronic Kidney Disease

Chronic kidney disease is a common kidney disorder in adult and aged dogs and cats; the management of associated complications and comorbidities generally requires a life-long medical treatment to ensure a good quality of life of affected patients. However, indications and the literature on drug dosing in dogs and cats with chronic kidney disease are often lacking. The aim of this review is to revise the current literature on drug dosing in canine and feline patients with renal impairment, with a special focus on the most commonly used medications to manage chronic kidney disease and possible comorbidities.