Serum symmetric dimethylarginine shows a relatively consistent long-term concentration in healthy dogs with a significant effect of increased body fat percentage

Longitudinal Study of Renal Health Screening in Apparently Healthy Aging Dogs

BACKGROUND

Combined measurement of functional, glomerular, and tubular markers in aging dogs is essential to detect early renal disease.

OBJECTIVES

Prospective longitudinal study to describe renal function and assess which biomarkers are associated with the development of early renal disease or death.

ANIMALS

One hundred and twenty-two apparently healthy senior and geriatric dogs.

METHODS

Prospective longitudinal study. Renal function was evaluated at baseline (T0) and every 6-12 months over 2 years, using systolic blood pressure measurements (SBP) and validated serum (creatinine, symmetric dimethylarginine, cystatin C [sCysC]), and urinary (specific gravity [USG], protein:creatinine [UPC], albumin:creatinine, retinol-binding protein:creatinine [uRBPcr]) biomarkers. Glomerular filtration rate (GFR) was measured in a subgroup. Survival models were used to assess the predictive value of measured biomarkers at baseline for the onset of azotemic chronic kidney disease (CKD) or death, respectively.

RESULTS

A total of 122 dogs were included; follow-up was available in 106 (T12) and 92 (T24); and GFR was estimated in 18 (T0), 11 (T12), and 10 (T24) dogs. Throughout the study, 15/122 (12%) dogs showed evidence of non-azotemic CKD, and in 11/106 (10%) dogs, azotemic CKD developed. Proteinuria was not associated with azotemic CKD, in contrast to muscle condition score, functional markers, and uRBPcr. Death was weakly associated with USG, UPC, and sCysC.

CONCLUSIONS AND CLINICAL IMPORTANCE

Over a 2-year period, 20% (26/122) of older dogs developed CKD, mostly persistent renal proteinuria (15/122). Muscle wasting and functional markers combined with uRBPcr had the best predictive value for the onset of azotemic CKD in these older, previously apparently healthy dogs.

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.

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.

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.

Effect of withholding food versus feeding on creatinine, symmetric dimethylarginine, cholesterol, triglycerides, and other biochemical analytes in 100 healthy dogs

BACKGROUND

Withholding food is often recommended before collection of blood for routine biochemical analysis in dogs despite a paucity of evidence to support this requirement.

OBJECTIVES

To compare measurements of selected biochemical analytes collected before and after feeding in clinically healthy dogs.

ANIMALS

One hundred clinically healthy staff- and student-owned dogs weighing ≥15 kg.

METHODS

Prospective observational study. Food was withheld from the dogs for 10-26 hours. Preprandial serum was collected, and then dogs were fed their usual food at an amount equivalent to at least 2/3 resting energy requirement (RER). Selected serum analytes were measured at 2-, 4-, 6-, and 8-hours postprandially. The proportion of postprandial values that exceeded either the reported allowable total error (TEa), or for symmetric dimethylarginine (SDMA), the reference change value (RCV), was determined. As neither TEa nor RCV is available for lipase, comparison was made to the high end of the reference interval (RI).

RESULTS

The proportion of dogs with at least 1 postprandial measurement that exceeded the TEa or RCV was 92/100 for triglycerides, 66/100 for blood urea nitrogen (BUN), 46/100 for phosphorus, 17/100 for glucose, 9/100 for bilirubin, 5/100 for SDMA, 2/100 for creatinine, and 0/100 for cholesterol and albumin. Postprandial lipase never exceeded the RI in dogs with normal fasted lipase.

CONCLUSIONS AND CLINICAL IMPORTANCE

Withholding food is generally not necessary before performing routine biochemical analysis in clinically healthy dogs. Withholding food might be helpful to limit variability in analytes impacted by feeding, such as triglycerides and phosphorus.

Using bioelectrical impedance analysis for modeling regression and predicting body fat accumulation in dogs in East Thailand

Background and Aim: Obesity in dogs leads to several health problems, such as premature death, and contributes to other diseases. Recently, body fat percentage has been considered to represent the body condition of dogs, and bioelectrical impedance analysis (BIA) is the most effective method for accurately measuring body fat in dogs. In Thailand, information on the body condition of dogs is limited, and there is no standard body fat level for Thai or mongrel dogs. This study was designed to evaluate and analyze the body fat percentage in dogs through BIA using a handheld instrument. The results of this study can help enhance the quality of life and health of dogs and aid in setting a standard body fat level for Thai or mongrel dogs. Materials and Methods: The body fat percentage of 340 Thai and mongrel dogs in East Thailand was measured in the standing position, and the body condition score (BCS) (range, 1–5), sex, sterilization status, age, type of diet, and lifestyle were recorded. A linear regression model was developed to compare the variables and the predicted body fat percentage, and multiple linear regressions were used to analyze the factors for body fat increment. Results: The linear regression model used to estimate the percentage of body fat (y) for each BCS (x) was y = 0.84 + 8.36x (R2 = 0.7219; p < 0.0001); the average body fat percentage was 27.52% for all studied dogs; specifically, 24.83% for the Thai Bangkaew, 26.42% for the Thai Ridgeback, and 27.65% for mongrels. The median body fat percentage was significantly higher in female than in male dogs. We found that as age increases, body fat percentage also increases; this increasing trend begins at the age of 5 years. However, increasing the level of activity and decreasing meal frequency leads to an increase in body fat percentage in neutered male dogs. Conclusion: The average body fat percentage of dogs in East Thailand is 27.52% and this value is expected to increase when these dogs reach the age of 5 years. BIA is a valid and effective measurement tool for detecting the body fat percentage in dogs.