Immunodeficiencies and immune-mediated disorders in foals

Abstract

From this theoretical review I can conclude that the basic understanding of the development and activation of the immune system is important because neonatal foals lack a functional adaptive immunity for a short period in their early life. The neonatal foal does develop an immune system but it is generally deficient in many cells at birth that are required to initiate the adaptive immunity. It is born into an environment full of microbes which challenge its defence. This exposure is important for its immune development but additional protection is ultimately required while its defence is being stimulated and developing. The downfall in neonatal foal immune protection is caused by the lack of maternal antibody transfer intra-uterine. The foal is therefore born immune deficient and its only means of defence is by maternal antibody- and lymphocyte-supplement through breast-feeding. For many reasons this passive transfer can fail leaving the foal vulnerable and susceptible to infectious agents. This process is called failure of passive transfer (FPT) and is the most common secondary immunodeficiency in neonatal foals. This deficiency leads to septicaemia which is the biggest cause of death in thus affected foals.