Acute metabolic responses to a combined viral-bacterial respiratory disease challenge in heifers administered transdermal flunixin meglumine

A trial was conducted to determine effects of altering time of transdermal flunixin meglumine (BTD; Banamine Transdermal, Merck Animal Health, Summit, NJ) administration relative to a viral-bacterial respiratory disease challenge in beef heifers. Thirty-two healthy heifers (170 ± 21.1 kg BW) were assigned to one of four treatments (n=8/treatment): 1) Control (CON), receiving no BTD; 2) Arrival (ARR), receiving BTD the day after arrival (-144h; 3.33 mg/kg BW); 3) Viral (VIR), receiving BTD at viral challenge (-72h); or 4) Bacterial (BAC), receiving BTD at bacterial challenge (0h). At -72h, all cattle received 1x108 PFU bovine herpesvirus-1 (BHV-1) intra-nasally and were returned to outdoor group-pens by treatment. At 0h, all cattle were challenged intra-tracheally with an average dose of 1.18x106 CFU Mannheimia haemolytica, fitted with an indwelling jugular catheter, and moved to individual stanchions in an environmentally controlled barn. Blood for serum was collected at -144h, -72h, at 1-h intervals from 0 to 8 h, and at 12, 24, 36, 48, 60, 72, and 144h relative to M. haemolytica challenge. Data were analyzed using the Mixed procedure of SAS specific for repeated measures with fixed effects of treatment, time, and their interaction. No significant treatment × time interactions were detected (P ≥ 0.31), with the exception of a tendency for serum cortisol (P = 0.058), where cortisol was greatest for the BAC treatment prior to the BHV-1 challenge. Serum cortisol, glucose, NEFA, and urea N concentrations were not affected by BTD administration at any time (P ≥ 0.78). These data indicate that cortisol concentration and metabolic indicators of disease were not affected by flunixin meglumine administered prior to or during a respiratory disease challenge. Furthermore, these data provide some evidence that flunixin meglumine does not affect metabolic or endocrine mediators measured for 144h after a combined viral-bacterial respiratory disease challenge in beef heifers.