Comparison of antemortem antimicrobial treatment regimens to antimicrobial susceptibility patterns of postmortem lung isolates from feedlot cattle with bronchopneumonia.

A retrospective study was performed to compare the treatment regimens in feedlot cattle that died with bovine respiratory disease (BRD) to the antimicrobial susceptibility patterns of the microorganisms isolated from lungs. Forty-three cattle submitted by the Willard Sparks Beef Research Center (WSBRC) to the Oklahoma Animal Disease Diagnostic Laboratory for postmortem examination during 2007 had bronchopneumonia (acute = 16, subacute = 5, or chronic = 22). Lungs from cattle were cultured aerobically (40 cattle) and for Mycoplasma spp. (34 cattle). Susceptibility panels were performed. At least 1 BRD pathogen (Mannheimia haemolytica, Pasteurella multocida, Histophilus somni, Mycoplasma bovis, or Arcanobacterium pyogenes) was isolated from 39 cattle, and 77% (30/39) had multiple organisms recovered. Mycoplasmal infections were common (25/34) and a major component of mixed infections (24/25). The majority (60%) of the M. haemolytica, P. multocida, and H. somni isolates were resistant to tetracycline. Most of the H. somni isolates (67%) were susceptible to tilmicosin (Ti), enrofloxacin (En), ceftiofur (Ce), and florfenicol, despite extensive treatment with Ti, En, and Ce (75% of isolates were from cattle that received each antimicrobial once). Most of the M. haemolytica (65%) and P. multocida (79%) isolates were susceptible to En and Ce, despite antemortem treatment of cattle with these antimicrobials. Hence, the current study reports a discrepancy between the antemortem treatment of clinical BRD and the susceptibility patterns of the bacteria isolated from lungs postmortem. Based on these findings, factors other than antimicrobial resistance are playing a role in the death of feedlot cattle with BRD.

Acquired cervical scoliosis attributed to Parelaphostrongylus tenuis infection in an alpaca.

CASE DESCRIPTION: A 2-year-old alpaca was evaluated because of acute onset of cervical scoliosis. CLINICAL FINDINGS: Physical examination revealed severe scoliosis of the caudal portion of the cervical vertebral column with a C-shaped curvature to the right side. No gait deficits were observed. Cervical radiography confirmed severe curvature of C4 to C6 but did not reveal any bony changes. Cerebrospinal fluid had high total protein concentration and extremely high nucleated cell count with a high proportion of eosinophils, suggesting parasitic infection. TREATMENT AND OUTCOME: The alpaca was treated for suspected parelaphostrongylosis with ivermectin, fenbendazole, flunixin, vitamin E, thiamine, physical therapy, and a custom-made neck brace. The alpaca's condition continued to deteriorate, and it developed tetraparesis and ataxia and was euthanized after approximately 1 month. Microscopic evaluation of the cervical spinal cord revealed marked vacuolar changes in the left medial portion of the ventral funiculus, mild lymphoplasmacytic infiltration, and multifocal granulomas. The lesions were continuous from C1 to C7 and were compatible with parasite migration. CLINICAL RELEVANCE: To the authors' knowledge, this is the first report of acquired scoliosis in an alpaca, which appears to represent an unusual manifestation of parelaphostrongylosis that was reported in horses.