Respiratory distress disorder caused by hyaline membrane disease (Figure 1) was diagnosed by Dublin in a two-day-old calf, which had been gasping since birth. Its lungs were very poorly aerated and non spongy. Neonatal hyaline membrane disease is wellrecognised in foals and is occasionally seen in calves. The pathogenesis in domestic species is assumed to result from a failure of the immature type two pncumocytes to secrete functional surfactant causing alveoli and small bronchioles to collapse on each exhalation. The tensions and shear stresses during reinflation of these collapsed airspaces injure type one pneumocytcs and Clara cells.
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