Evaluation of assays for determination of passive transfer status in neonatal llamas and alpacas

Objective-To evaluate several practice-adapted assays for determination of passive transfer status in crias. Animals-24 Ilama and 9 alpaca crias. Design-Prospective study. Procedure-Serum IgG concentration was measured by use of a radial immunodif fusion assay when crias were 45 to 51 hours old. Results were compared with serum gamma-glutamyltransferase (GGT) activity, serum total protein, album in, globulin, and total solids concentrations, and results of commercially available and traditional sodium sulfite turbidity (SST) tests. Results-Mean (+/- SD) serum IgG concentration was 1,762 +/- 1,153 mg/dl. On the basis of a threshold value of 1,000 mg of IgG/dl at 48 hours of age, 5 of 33 (15.15%) crias had failure of passive transfer. Serum total solids, protein, and globulin concentrations were significantly associated with ser um IgG concentration, whereas serum GGT activity and serum albumin concentr ation were not. Serum IgG concentrations were significantly different among crias with negative, 2+, and 3+ scores on the traditional SST test. Serum IgG concentrations were not significantly different between crias with nega tive and 100 mg/dl scores or 100 and 300 mg/dl scores on the commercially a vailable SST test. However, all other comparisons between crias with differ ent scores revealed significant differences. Sensitivity and specificity ra nged between 0 and 1, depending on the test and endpoint selected. Conclusions and Clinical Relevance-The commercially available SST test and determination of serum total protein and globulin concentrations are suitab le methods for assessing passive transfer status in Ilama and alpaca crias.