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Bone Marrow Response in Cattle with Chronic Dermatitis Caused by Psoroptes ovis
- Stromberg, P. C., Guillot, F. S.
- Hereford, Psoroptes ovis, anemia, animal pathology, biopsy, bone marrow, calves, dermatitis, eosinophils, fibrinogen, heifers, hyperplasia, lymphocytes, mites, neutropenia, neutrophils
- Six Hereford heifer calves were infested with Psoroptes ovis and compared to six uninfested control calves. Infested calves developed severe exudative dermatitis which covered 100% of the body surface by 7 weeks after infestation. They developed moderate nonregenerative anemia, decreased numbers of neutrophils and lymphocytes, and increased plasma protein and fibrinogen concentrations. Sternal marrow core biopsies taken 7 weeks after infestation were 75 to 90% cellular, while cores from uninfested calves were 10 to 20% cellular. Comparison of myelograms between the two groups of calves revealed increased M: E ratio, myelocyte and metamyelocyte hyperplasia with depletion of mature neutrophils and eosinophils in the P. ovis-infested calves. It was concluded that P. ovis-infested calves develop myeloid hyperplasia and that mange-related neutropenia is not due to bone marrow suppression by a mite or scab-associated toxin.