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To develop appropriate reference ranges for plasma IgG concentrations of llamas.


643 llamas on 5 farms.


Plasma IgG concentration was measured by using a single radial immunodiffusion assay kit. Farm of origin, age, body condition score, and sex were recorded for each llama. The effect of each factor on plasma IgG concentration was evaluated separately, using ANOVA; the association between age and IgG concentration was evaluated, using linear regression. Multivariable regression models were developed to examine concurrent effects of age, sex, body condition score, farm, and various interactions on IgG concentration.


The IgG concentrations were between 127 and 3,969 mg/dl. In llamas < 12 months old, farm of origin accounted for 29% of variability for IgG concentration. Reference range for plasma IgG concentrations in llamas < 12 months old was 391 to 2,357 mg/dl; for llamas > 12 but < 28 months old was 771 to 2,796 mg/dl; and for llamas > 28 months old was 570 to 3,264 mg/dl. These ranges were applicable only for the kit used in this study.


Healthy llamas have a wide range of IgG concentrations. Determinants of IgG concentration are multifactorial, and their importance varies with age of the llamas.

Clinical Implications

The wide range of IgG concentrations observed in healthy llamas and the influence that age and farm may have on IgG concentrations indicate that a result for one specific llama should be interpreted in relation to those of its herdmates. (Am J Vet Res 1998;59:406–409)

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in American Journal of Veterinary Research