Changes of clinical, electrolytes, acute phase proteins, and some cardiovascular biomarkers in lambs and kids from birth to 2 days of age

Fetal cardiac troponin I levels decline toward birth in sheep

Elevated cardiac troponin I (cTnI), a myocardial damage biomarker, has been reported in cord blood of neonates delivered vaginally or by cesarean section. Although the neonatal peak likely reflects the physiological adjustment to extrauterine life, a better understanding of serial prepartum changes is required to determine physiological causes of fetal cTnI release. We longitudinally sampled eight healthy lambs (20 days before spontaneous birth to 5 days postnatal), and from three fetuses receiving intravenous IGF-1. Samples were collected into heparin, and the plasma was stored at -80°C for later determination of high-sensitivity (hs) cTnI levels (BeckmanCoulter UniCel DxI Access IA; log transformed detection limit = 0.30, quantification limit = 0.78, 99th percentile = 1.78). Positive and negative control samples were drawn from an adult ewe during a terminal experiment (myocardial ischemia) and similarly assessed. hs-cTnI data were log transformed from ng/L. Log(hs-cTnI) was 1.47 ± 0.30 (means ± SD) at 20 days before birth and declined to 1.02 ± 0.65 in fetuses 12 ± 4 h before birth (P < 0.0001, R2 = 0.7869). Birth stimulated a delayed, transient peak in hs-cTnI (P = 0.0058). Newborn (43 ± 19 min postnatal) levels were 1.39 ± 0.40 (P = 0.0650 vs. fetus on day of birth) and 2.14 ± 0.63 the day after birth (P = 0.0331 vs. newborn). The second day after birth, levels declined to 1.65 ± 0.48 (P = 0.0238 vs. day 1). IGF-1 infusion increased hs-cTnI levels 25-50% over baseline (P = 0.0252, R2 = 0.9938). Baseline adult ewe log(hs-cTnI) was below the limit of detection; 3 h following coronary artery ligation, levels were 3.21. In conclusion, we newly report that fetal hs-cTnI levels decline concomitantly with reduced proliferation of cardiomyocytes toward term.NEW & NOTEWORTHY Serial blood samples were collected from catheterized, normally developing fetal and newborn lambs and high-sensitivity cardiac troponin I (hs-cTnI) levels were assessed, providing unprecedented insight into the physiological processes leading to high levels in the perinatal period. Moderately high levels of hs-cTnI found in the normally developing fetus declined toward term. An elevation to high levels peaked the day after birth, after which hs-cTnI declined again. Stimulation of fetal cardiomyocyte proliferation with IGF-1 also elevated hs-cTnI.

Reference intervals for serum amyloid A, haptoglobin, ceruloplasmin, and fibrinogen in apparently healthy neonatal lambs

BACKGROUND

Acute-phase proteins (APPs) are considered biomarkers for diagnoses, prognoses, and treatment and health status monitoring. Reference intervals (RIs) are an integral part of diagnostic laboratory testing and clinical decision-making. The RIs for neonatal lambs are lacking.

OBJECTIVE

This study aimed to determine the RIs of serum amyloid A (SAA), haptoglobin (Hp), ceruloplasmin (Cp), and fibrinogen (Fb) concentrations in neonatal cross-bred Kivircik lambs.

METHODS

The study consisted of 42 neonatal cross-bred Kivircik lambs. Physical examinations were performed daily, and blood samples were collected at 0 (precolostrum), 1, 3, 7, 14, 21, and 28 days of age. The RIs of SAA, Hp, Cp, and Fb concentrations were calculated according to the recommendation of the American Society for Veterinary Clinical Pathology. Results were also evaluated for age- and sex-related effects.

RESULTS

The RI for serum Hp was 0-0.4 g/L, and no apparent effect of age or sex was noted. Because of significant age- and sex-related differences, the SAA (0.34-55.12 µg/mL), Cp (2.4-26.07 mg/mL), and Fb (218.86-527.82 mg/mL) results were given as minimum and maximum values. Serum SAA on the 1st, 3rd, and 7th days of life, and Cp and Fb concentrations on the 14th and 21st days of life, were significantly higher than those on other study days.

CONCLUSIONS

This study is the first to establish RIs for neonatal lambs, and the values obtained could be useful for making clinical decisions regarding cross-bred Kivircik lambs during this critical period.