Septicemic pasteurellosis in free-ranging neonatal pronghorn in Oregon

As part of a study to determine the cause(s) of population decline and low survival of pronghorn (Antilocapra americana) neonates on Hart Mountain Nat ional Antelope Refuge (HMNAR), Oregon (USA), 55 of 104 neonates captured du ring May 1996 and 1997 were necropsied (n = 28, 1996; n = 27, 1997) to dete rmine cause of death. Necropsies were conducted on fawns that died during M ay, June, or July of each year. The objectives of this study were to report the occurrence and pathology of pasteurellosis in neonates and determine i f the isolated strain of Pasteurella multocida was unique. Septicemic paste urellosis, caused by P. multocida, was diagnosed as the cause of death for two neonates in May and June 1997. Necropsy findings included widely scatte red petechial and ecchymotic hemorrhages found over a large portion of the subcutaneous tissue, meninges of the brain, epicardium, skeletal muscle, an d serosal surface of the thorasic and abdominal cavities. Histological exam ination of lung tissues revealed diffuse congestion and edema and moderate to marked multifocal infiltrate of macrophages, neutrophils, and numerous b acteria within many terminal bronchioles and alveoli. Pasteurella multocida serotypes A:3,4, and B:1 were isolated from several tissues including lung , intestinal, thorasic fluid, and heart blood. Each B:1 isolate had DNA res triction endonuclease fingerprint profiles distinct from isolates previousl y characterized from domestic cattle, swan (Olor spp.), moose (Alces alces) , and pronghorn from Montana (USA). This is the first report of pasteurello sis in pronghorn from Oregon and the B:1 isolates appear to be unique in co mparison to DNA fingerprint profiles from selected domestic and wild specie s.