RESUMEN
Twenty-five hybrid dogs were injected intravenously with oleic acid of the dose 0.3 ml/kg of body weight to prepare a model of respiratory distress syndrome (RDS) . The animals were killed 24 hours after injection. PaO2, PaCO2 and pH of the arterial and mixed venous blood were determined before and immediately, 0.5, 1?2, 4, 6, 22 and 24 hours after injection. The average pulmonary arterial pressure was measured hourly. The chest x-ray films were taken 2,4, 6 and 24 hours after injection. The electrolytes T3, T4, the hematocrit and RBC count, and the serum corticosteroid level were measured before and 24 hours after injection.25 dogs were divided into two groups; the control group consisted of 8 dogs and the therapeutic group consisted of 17 dogs, among which nine were treated with hyosine hydrobromide and 8 with dexamethasone. The histologic specimens of the animals of the control group and hyosine hydrobromide treated group were examined with both light and electron microscopes but the specimens of the animals of dexamethasone treated group were examined with light microscope only.It was found that dexamethasone is effective in the treatment of RDS produced with oleic acid injection while hyosine hydrobromide is of no value.