EFFICIENCY OF 5-HYDROXYTRYPTAMINE RECEPTOR BLOCKADE AS THERAPEUTIC MEASURE DURING ACUTE RESPIRATORY-DISTRESS SYNDROME IN DOUBLE-MUSCLED CATTLE

During this investigation, which involved 58 Belgian White and Blue double-muscled calves affected by a naturally occurring Acute Respiratory Distress Syndrome, the clinical efficiency of a 5-HT2 receptor blockade with metrenperone (group A) was compared to the efficiency of a nonsteroidal (flunixine meglumine - group B) and a steroidal (prednisolone sodium succinate-group C) antiinflammatory drug. Each animal of this trial was treated with ceftiofur sodium as antimicrobial agent. A clinical score and a breathing score were calculated at each step of the investigation period, i. e. before (T 0) and 1 hour (T 1), 12 hours (H), 24 H, 48 H and 168 H (T 3) after the first treatment, the interval 12 H - 48 H being considered as period T 2. Three clinical parameters were also taken into account separately: rectal and peripheral temperatures and heart rate. A significant improvement of the clinical score was registered at T 2 in group A and at T 3 in groups A and B, while this score did not significantly change in group C. In group A, the breathing score was significantly improved at T 2 and T 3, but not in groups B and C. Peripheral and rectal temperatures recorded at T 1 were, in group A, significantly increased and decreased respectively, but not significantly changed in groups B and C. The proportions requiring change of treatment during the investigation period were significantly (P = 0.022) different in the three groups, being 5.6, 21.4 and 50.0 % in groups A, B and C respectively. In conclusion, compared with flunixine meglumine and prednisolone sodium succinate, metrenperone significantly reduced the proportion requiring treatment change in double-muscled calves affected by a naturally occurring Acute Respiratory Distress Syndrome. Furthermore, the respiratory and clinical status of the animals subjected to such a 5-HT2 receptor blockade improved more quickly.