F03 - Assessment of an Immunocrit Method to Detect Failure of Passive Transfer in Crias

Abstract:

Background: Failure of passive transfer is associated with diarrhea, septicemia, arthritis, omphalitis, pneumonia and increased mortality in crias. Direct measurement of immunoglobulin through radial immunodiffusion (RID) is the most common laboratory method of evaluating passive transfer, but results take 24 hours. This study evaluates two field-friendly methods: measurement of total solids and ammonium sulfate precipitation (immunocrit method). Immunocrit has been assessed in multiple species, but not crias. Hypothesis/

Objectives: To evaluate the ability of immunocrit measurement to detect failure of passive transfer in crias, compared to RID and total solids measurement. Animals: 50 client-owned alpaca crias, with owner consent. Blood was collected 24 hours after birth and stored for later analysis.

Methods: Total plasma solids were measured via refractometry. Immunocrit was determined by precipitating protein in plasma with ammonium sulfate in a microhematocrit tube. RID was measured using a commercial RID kit.

Results: The immunocrit method (R-squared = 0.46) and total solids measurement (R-squared = 0.52) had similar correlations to RID. In calculating sensitivity and specificity, an immunocrit cutoff value of < 12 % would have a 100 % sensitivity and 84.44 % specificity for detection of failure of passive transfer. Conclusions & Clinical Importance: This study represents the first assessment of the immunocrit method in crias. It appears to be a simple, inexpensive method to estimate immunoglobulin. Unlike studies in other species, comparison with total solids was performed and revealed immunocrit demonstrated a similar ability as total solids to estimate IgG.