Abstract
The aim of this study was to correlate the serum levels of acute phase proteins (APPs) and cytokines in response to treatment by various antimicrobial agents in feedlots calves (FL) naturally infected with Mannheimia haemolytica (M. haemolytica) and Histophilus somni (H. somni). 840 feedlot calves in one farm in Al-Kharg region, Saudi Arabia were clinically examined for the presence of respiratory disease manifestations. The infection was confirmed using nasopharyngeal swabs. Blood samples from diseased animals were collected before and after (7 days) treatment for biochemical analysis of serum amyloid A (SAA), haptoglobin (HP) and cytokines tumor necrosis factor alpha (TNF-alpha), interferon gamma (IFN-gamma), interleukin-1 beta (IL-1 beta), and interleukin-8 (IL-8). FL that were positive for M. haemolytica and/or H. somni (n=69) received treatment with one antibiotic, including tulathromycin (Tula; n=26 cases), florfenicol (FFC; n=19), tilmicosin (Tm; n=13), or ceftiofur (CEF; n=11) and one non-steroidal anti-inflammatory drug (Flunixin meglumine (FM; n=43) or phenylbutazone (PBZ; n=26). We demonstrated the selective potent inhibitory effect of the administrated anti-inflammatory agents either FM or PBZ on the production of APPs and pro-inflammatory cytokines in FL infected with bovine respiratory disease (BRD). Our findings showed the antibacterial efficacy of FFC and Tm for the treatment of infected FL when administrated with either FM or PBZ. However, Tula was preferable to administrate in combination with FM for the treatment of FL with respiratory manifestations. Importantly, monitoring the sera level of Hp, IL-1 beta, and interleukin-8 (IL-8) in feedlots treated with either FM combined with Tula, FFC, or Tm or PBZ combined with FFC, and Tm has been effective in predicting the disease prognosis. (C)2020 PVJ. All rights reserved