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. 2021 Nov;35(6):2891-2896.
doi: 10.1111/jvim.16295. Epub 2021 Nov 5.

Symmetric dimethylarginine concentrations in healthy neonatal foals and mares

Rana Bozorgmanesh  1 , Jessica Thornton  1 , Jackie Snyder  1 , Caitlin Fletcher  1 , Rebekah Mack  2 , Michael Coyne  2 , Rachel Murphy  2 , Evan Hegarty  2 , Nathan Slovis  1
Affiliations

Symmetric dimethylarginine concentrations in healthy neonatal foals and mares

Rana Bozorgmanesh et al. J Vet Intern Med. 2021 Nov.

Abstract

Background: Symmetric dimethylarginine (SDMA) is a renal biomarker correlated with glomerular filtration rate (GFR).

Objectives: Describe changes in SDMA in clinically healthy foals and their mares during the first month postfoaling.

Animals: Convenience sampling of healthy periparturient Thoroughbred mares and their full-term foals from a population of client-owned horses.

Methods: Serum and EDTA whole blood samples were collected from mares in their last month of pregnancy and then from mares and foals at approximately <12 hours, 48 hours, 7 days, and 30 days postbirth. Samples were processed at a commercial reference laboratory for CBC and serum biochemistry, including SDMA concentrations.

Results: A total of 125 foals and 104 mares were included. Upper limits for SDMA concentrations in foals were above the adult horse reference interval for the first 20 or more days of life. Median SDMA concentrations decreased from 70 μg/dL (range, 7-100 μg/dL) to 18 μg/dL (range, 6-27 μg/dL) during the first 3 to 4 weeks of life. At birth, the SDMA concentration reference range was established as 0 to 100 μg/dL (upper limit of the assay); 0 to 85 μg/dL for 1 to 4 days old, 0 to 36 μg/dL for 5 to 10 days old, and 0 to 24 μg/dL for 20 to 30 days old. The upper reference limits for SDMA concentrations in mares did not differ from the general reference interval for adult horses. No correlation was identified between mare and foal SDMA concentrations (ρ = .06, P = .58).

Conclusions and clinical importance: Foal SDMA concentrations remained higher than the upper limit of the adult reference range and foals require a different reference range dependent on age.

Keywords: horse; kidney; neonate; renal.

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Conflict of interest statement

Rebecca Mack, Michael Coyne, Rachel Murphy, Evan Hegarty have an affiliation with the commercial funders of this research as current employees of IDEXX Laboratories, Inc (https://www.idexx.com/en/about-idexx/).

Figures

FIGURE 1
FIGURE 1
Foal symmetric dimethylarginine (SDMA) and serum creatinine concentrations (sCr) at the different age ranges throughout the study period. The upper reference limits are illustrated with the red lines for each age range, with the dashed red lines representing the 95% confidence intervals. (A) Foal SDMA concentrations. The dashed black line represents the upper limit of the adult reference range (14 μg/dL). (B) Foal sCr. The dashed black line represents the upper limit of the adult reference range (1.8 mg/dL)
FIGURE 2
FIGURE 2
Mare symmetric dimethylarginine (SDMA) and serum creatinine concentrations (sCr) at the different age ranges throughout the study period. The upper reference limits are illustrated with the red lines for each age range, with the dashed red lines representing the 95% confidence intervals. (A) Mare SDMA concentrations. The dashed black line represents the upper limit of the adult reference range (14 μg/dL). (B) Mare sCr. The dashed black line represents the upper limit of the adult reference range (1.8 mg/dL)
FIGURE 3
FIGURE 3
Correlation between paired mare and foal symmetric dimethylarginine (SDMA) and serum creatinine concentrations (sCr) at birth. (A) SDMA, illustrating no evidence of correlation (ρ = .06, P = .58). (B) SCr, illustrating no evidence of correlation (ρ = .13, P = .27)
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