Texas Equine Veterinary Association

www.texasequineva.com • 12 (USG<1.008) due to the high liquid diet. Blood urea nitrogen (BUN) is similar to adult RR at birth and is decreased in foals up to two months of age. Foal lactate is elevated at birth and will decrease within the first 24 hours. Persistent or increasing lactate levels are most commonly due to tissue hypoxia or decreased perfusion, with other causes including sepsis/SIRS, seizures, and hepatic disease. Due to the epitheliochorial placenta, foal's have low levels of immunoglobulin at birth and rely on passive transfer of colostral immunity through suckling. Moderate to severe hypoproteinemia is common in foals who have not nursed. Albumin is similar to adult horses at birth and may decrease with post-foaling fluid shis, with most foals having low-normal or mild hypoalbuminemia compared to adult RR. If globulins are elevated at birth, this is indication of an in-utero antigenic stimulation. While adult references ranges are not translatable to the neonatal population, knowing and understanding differences in neonatal physiology and the effects on serum biochemistry reference ranges can help guide on farm evaluation and improve care for foals as they start to come into the clinic. NEONATAL REFERENCE RANGES Figure 1: COMPLETE BLOOD COUNT At birth 24 hours 1 week Hematocrit % 40–52 32–46 28–43 Total White Blood Cell (WBC) cells/μL 6.9–14.4 4.9–11.7 6.3–13.6 Neutrophils cells/μL 5.61–2.4 3.4x–9.6 4.4–10.6 Lymphocytes cells/μL 0.5–2.5 0.7–2.1 1.4–2.3 Figure 2: INFLAMMATORY MARKERS Fibrinogen: At birth: 50–300 mg/dL At 24 hours: 100–400 mg/dL SAA: Days 1-3 27.1 (0–98.8) mg/L SERUM C Figure 3: SERUM CHEMISTRY <12 hours* 24 hours 1 week Creatine kinase (CK) At birth 24 hours 1 week Aspartate transami- nase (AST) U/L 97–315 146–340 237– 620 Alkaline phospha- tase (ALP) U/L 152–2835 861– 2671 137– 1169 Gamma-glutamyl transferase (GGT) U/L 13–39 18–43 14–64 Sorbitol dehydroge- nase (SDH) U/L 1–21** -- 1–18 Total bilirubin mg/dL 0.8–2.8 1.6–5 0.8– 2.9 Serum bile acids μmol/L 22–82** -- 17–29 Creatinine mg/dL 0.15–0.37 0.11– 0.38 0.09– 0.15 BUN mg/dL 12–27 9–40 4–20 Total protein g/dL -- 4.1–6.6 -- Albumin g/dL -- 2.5–3.5 -- *Aer suckling **Prior to suckling Aoki, T., & Ishii, M. (2012). Hematological and Biochemical Profiles in Peripartum Mares and Neonatal Foals (Heavy Dra Horse). Journal of Equine Veterinary Science, 32(3), 170–176. https://doi.org/10.1016/j.jevs.2011.08.015 Axon, J. E., & Palmer, J. E. (2008). Clinical Pathology of the Foal. Veterinary Clinics of North America - Equine Practice, 24(2), 357–385. https://doi.org/10.1016/j.cveq.2008.03.005 Barton, M. H., & Hart, K. A. (2020). Clinical Pathology in the Foal. Veterinary Clinics of North America - Equine Practice, 36(1), 73–85. https://doi.org/10.1016/j.cveq.2019.11.003 LAVOIE, J. P., MADIGAN, J. E., CULLOR, J. S., & POWELL, W. E. (1990). Haemodynamic, pathological, haematological and behavioural changes during endotoxin infusion in equine neonates. Equine Veterinary Journal, 22(1), 23–29. https://doi. org/10.1111/j.2042-3306.1990.tb04198.x Sgorbini, M., Bonelli, F., Rota, A., Baragli, P., Marchetti, V., & Corazza, M. (2013). Hematology and Clinical Chemistry in Amiata Donkey Foals from Birth to 2 Months of Age. Journal of Equine Veterinary Science, 33(1), 35–39. https://doi.org/10.1016/j. jevs.2012.04.010 Stoneham, S. J., Palmer, L., Cash, R., & Rossdale, P. D. (2001). Measurement of serum amyloid A in the neonatal foal using a latex agglutination immunoturbidimetric assay: Determina- tion of the normal range, variation with age and response to disease. Equine Veterinary Journal, 33(6), 599–603. https://doi. org/10.2746/042516401776563472

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