Assessing Failure of Passive Transfer in Foals

Veterinarians can easily determine whether a foal is suffering from failure of passive transfer using the immunocrit method.

The article “Assessment of the immunocrit method to detect failure of passive immunity in newborn foals” was authored by E. Mortola, G. Miceli, L. Alarcon, M. Azcurra and A. Larsen.

This study assessed the validity of the immunocrit method to detect failure of passive transfer (FPT) in foals. The technique, which is inexpensive and provides results within minutes, is based on the ability of ammonium sulphate to precipitate the immunoglobulin fraction of serum.

A total of 211 newborn Thoroughbred foals were included in the study over a two-year period. Blood samples were obtained when the foals were 10–14 hours old and after foals had suckled from their dams. 

A 40% ammonium sulphate solution was used to precipitate the immunoglobulins in the serum, and the separation between the precipitate and the liquid supernatant was measured using a haematocrit reader. The assay was performed in triplicate and included a negative control with a serum sample taken before the foal suckled colostrum. Results were compared with those of agarose gel electrophoresis, which also measures total immunoglobulins.

The values obtained by the immunocrit method were significantly correlated (R = 0.871; P<0.001) with those measured by agarose gel electrophoresis. A cut‐off value of 8 g/L of serum immunoglobulins by agarose gel electrophoresis and its equivalent of 9.5% for the immunocrit test was indicative of FPT. The sensitivity and specificity of the immunocrit method at this cut‐off point were 94% and 82%, respectively.

Bottom line: The immunocrit test is a quantitative, quick, inexpensive, reliable and objective method to detect FPT in foals.

You can access this article from the Wiley online library.