title: Lung pathology and infectious agents in fatal feedlot pneumonias and relationship with mortality, disease onset, and treatments.
abstract: This study charted 237 fatal cases of bovine respiratory disease (BRD) observed from May 2002 to May 2003 in a single Oklahoma feed yard. Postmortem lung samples were used for agent identification and histopathology. Late in the study, 94 skin samples (ear notches) were tested for Bovine viral diarrhea virus (BVDV) by immunohistochemistry (IHC). Bovine respiratory disease morbidity was 14.7%, and the mortality rate of all causes was 1.3%, with more than half (53.8%) attributed to BRD (0.7% total of all causes). The agents isolated were the following: Mannheimia haemolytica (25.0%), Pasteurella multocida (24.5%), Histophilus somni (10.0%), Arcanobacterium pyogenes (35.0%), Salmonella spp. (0.5%), and Mycoplasma spp. (71.4%). Viruses recovered by cell culture were BVDV-1a noncytopathic (NCP; 2.7%), BVDV-1a cytopathic (CP) vaccine strain (1.8%), BVDV-1b NCP (2.7%), BVDV-2a NCP (3.2%), BVDV-2b CP (0.5%), and Bovine herpesvirus 1 (2.3%). Gel-based polymerase chain reaction (PCR) assays were 4.6% positive for Bovine respiratory syncytial virus and 10.8% positive for Bovine coronavirus. Bovine viral diarrhea virus IHC testing was positive in 5.3% of the animals. The mean values were determined for the treatment data: fatal disease onset (32.65 days), treatment interval (29.15 days), number of antibiotic treatments (2.65), number of different antibiotics (1.89), and day of death (61.81 days). Lesions included the following: 1) duration: acute (21%), subacute (15%), chronic (40.2%), healing (2.8%), normal (18.1%), and autolyzed (2.8%); 2) type of pneumonia: lobar bronchopneumonia (LBP; 27.1%), LBP with pleuritis (49.1%), interstitial pneumonia (5.1%), bronchointerstitial pneumonia (1.4%), septic (0.9%), embolic foci (0.5%), other (2.8%), normal (10.3%), and autolyzed (2.8%); and 3) bronchiolar lesions: bronchiolitis obliterans (39.7%), bronchiolar necrosis (26.6%), bronchiolitis obliterans/bronchiolar necrosis (1.4%), other bronchiolar lesions (6.5%), and bronchiolar lesion negative (25.7%). Statistically significant relationships were present among the agents, lesions, and the animal treatment, disease onset, and mortality data. Clinical illnesses observed in this study were lengthier than those reported 16-20 years ago, based on fatal disease onset, treatment interval, and day of death.
authors: Department of Veterinary Pathobiology, Room 250, McElroy Hall, Center for Veterinary Health Sciences, Oklahoma State University, Stillwater, OK 74078, USA. robert.fulton@okstate.edu
authors: Robert W
authors: RW
authors: Fulton
authors: K Shawn
authors: KS
authors: Blood
authors: Roger J
authors: RJ
authors: Panciera
authors: Mark E
authors: ME
authors: Payton
authors: Julia F
authors: JF
authors: Ridpath
authors: Anthony W
authors: AW
authors: Confer
authors: Jeremiah T
authors: JT
authors: Saliki
authors: Lurinda T
authors: LT
authors: Burge
authors: Ronald D
authors: RD
authors: Welsh
authors: Bill J
authors: BJ
authors: Johnson
authors: Amy
authors: A
authors: Reck
mesh_terms: D000818:Animals; D000900:Anti-Bacterial Agents / Q000627:therapeutic use; D001424:Bacterial Infections / Q000401:mortality / Q000662:veterinary; D048090:Bovine Respiratory Disease Complex / Q000188:drug therapy / Q000401:mortality* / Q000473:pathology; D002417:Cattle; D002418:Cattle Diseases / Q000382:microbiology / Q000473:pathology*; D006799:Housing, Animal; D008168:Lung / Q000382:microbiology / Q000473:pathology*; D011014:Pneumonia / Q000188:drug therapy / Q000401:mortality / Q000662:veterinary*; D014777:Virus Diseases / Q000401:mortality / Q000662:veterinary
chemical_list: D000900:Anti-Bacterial Agents