ALB and susceptibility to pneumonia measurement: Serum concentration of total plasma proteins and albumin did not differ between the two groups studied, which was expected, since, to the author’s knowledge, they have not been directly related to the development of pneumonia by R. equi. However, we included these parameters as a measurement of total proteins and albumin are routinely assessed in the evaluation of neonatal foals to assess the degree of dehydration and/or failure of passive transfer of immunity, together with other markers such as urine density and IgGs.