Reference intervals for electrolytes and serum pH in adult alpacas (Vicugna pacos, Linnaeus 1758) raised in Uruguay

Abstract

The alpaca (Vicugna pacos, Linnaeus 1758) a native Andean domestic camelid. In Uruguay, it's an exotic resource introduced for recreation (bioparks, rural tourism establishments) and protection of sheep from wild and domestic predators. Physiological levels upon acclimatization to low altitudes, four distinct seasons, and high winter relative humidity are unknown. This study sought to estimate Reference Intervals (RI) for serum electrolyte profiles in adult alpacas and to evaluate the sex effect. In the winter of 2014, a random sample of 24 apparently healthy adults was taken, 13 males and 11 females of the Huacaya breed, raised outdoors at a tourist establishment in Punta del Este, Maldonado (latitude 34.4°S, longitude 55.0°W, altitude 60 m a.s.l.). Peripheral blood was drawn into dry serum tubes by veterinarians at the facility. Serum was centrifuged (5000 rpm) in a private laboratory and refrigerated until values ​​were determined using a flame spectrophotometer. Eosinophil count was the exclusion criterion, eliminating samples outside the Oregon Veterinary Diagnostic Laboratory RI (687-4867 cells/mL). Descriptive statistics, exploratory analysis, and RI calculation with Confidence Intervals (CI, 90%) were performed using the Reference Value Advisor V2.1 using a standard or robust method, following guidelines from the American Society for Veterinary Clinical Pathology (ASVCP) for samples less than 40 with parametric distribution (with or without Box-Cox transformation). The sex effect was evaluated (alpha: 0.05). The means and RI (CI in parentheses) were for Sodium 152.6 mEq/L, from 147.4 (146.4-149.3) to 157.9 (156.8-159.5); for Potassium 6.0 mEq/L, from 4.6 (4.4-4.9) to 7.8 (7.2-8.5); for Chlorine 112.8 mEq/L, from 107.6 (106.9-108.9) to 118.0 (115.9-119.7); for ionized Calcium 4.9 mg/dL, from 4.1 (4.0-4.3) to 5.5 (5.3-5.7); for total calcium 9.5 mg/dL, from 8.2 (7.8-8.6) to 10.8 (10.5-11.2) and for pH 7.8, from 7.4 (7.2-7.5) to 8.1 (8.0-8.2). There were no significant differences by sex for any variable.