The incidence and consequences of failure of passive transfer of immunity on a thoroughbred breeding farm.

This research study monitors the concentration level of IgG (antibodies) in newborn foals, demonstrating that failure of passive transfer of immunity from mother to offspring contributes to the development of septic illness within the first month of life. Foals born later in the season had a higher risk of failing to receive maternal immunity, as did those that required assistance at birth or those born from a mare with peripartum complications.

Methodology

• The research took place over three consecutive years on a Thoroughbred breeding farm, involving 323 foals.
• The concentration of the foals’ circulating IgG was measured between 12 and 24 hours after birth.
• The criteria used to define failure of passive transfer (FPT) was a foal circulating IgG concentration of less than 8g/L.

Findings

• The incidence of FPT in the foals was found to be 9.6%.
• Foals born later in the season (i.e. between October and December) were more likely to have FPT.
• Foals that required significant assistance at birth or were born to a mare with periparturient issues were also more likely to be subjected to FPT.

Impact of FPT

• It was noted that failing to receive passive immunity significantly increased the foal’s chances of developing various septic illnesses within the first month of life, such as joint ill, septicaemia, and pneumonia.
• Although susceptible to these conditions, FPT was not found to have a significant effect on the likelihood of the foal developing diarrhoea or Rhodococcus equi pneumonia.

Conclusion and Recommendations

• The results highlight the importance of monitoring the passive immune status of newborn foals to detect potential cases of FPT early on.
• It is recommended that foals considered at risk for FPT should be given early treatment to prevent the onset of diseases.