Comparison of methods for measuring serum immunoglobulin concentrations in neonatal llamas

Blood samples were collected from 25 neonatal llamas before suckling and at 24, 48, 72, 96, and 120 hours of age. Nine tests for determining serum immunoglobulin concentrations were performed on each sample, to compare within-test variation and correlations among tests. The single radial immunodiffusion assay was the only quantitative test and therefore, was judged the most accurate test for determining the status of passive transfer of immunoglobulins in neonatal llamas. Measurement of globulin concentration and total serum protein, and the sodium sulfite precipitation test were accurate when compared with radial immunodiffusion assay results. Measurements of total serum solids by use of a hand-held refractometer and of albumin concentration, and the zinc sulfate turbidity and 10% glutaraldehyde coagulation tests were not reliable for detecting failure of passive transfer in neonatal llamas. Ten of 25 neonatal llamas were suspected of having partial to complete failure of passive transfer on the basis of results of the single radial immunodiffusion assay. The other tests used in this study identified between 4 and 7 of these 10 llamas at 24 hours of age. On follow-up communication 4 to 6 months after the last-blood sample collection, none of the 25 llamas were identified as having been clinically ill or had received any treatments for illness associated with low immunoglobulin concentrations.