Feline immunodeficiency virus associated myopathy in the adult cat

Authors

  • Michael Podell MSc, DVM,

    Corresponding author
    1. Department of Veterinary Clinical Sciences, College of Veterinary Medicine, The Ohio State University, Columbus, Ohio 43210, USA
    2. Comprehenisve Cancer Center, The Ohio State University, Columbus, Ohio, USA
    • Department of Veterinary Clinical Sciences, College of Veterinary Medicine, The Ohio State University, Columbus, Ohio 43210, USA
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  • Esther Chen BS,

    1. Department of Veterinary Clinical Sciences, College of Veterinary Medicine, The Ohio State University, Columbus, Ohio 43210, USA
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  • G. Diane Shelton DVM, PhD

    1. Comparative Neuromuscular Laboratory, Department of Pathology, University of California, San Diego, La Jolla, California, USA
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Abstract

Human immunodeficiency virus (HIV-1) associated myopathy can be a debilitating disease in humans, leading to weakness, myalgia, and muscle wasting. Subclinical neuromuscular involvement is also common. A range of histologic lesions have been described in both forms that include both inflammatory and degenerative changes. The purpose of this study was to determine whether a myopathy was present in adult cats experimentally infected with feline immunodeficiency virus (FIV). Six specific pathogen-free, laboratory-housed cats were challenged intravenously with 1000 TCID50 of the Maryland isolate of FIV (FIV-MD) at 8 months of age. The highest serum creatine kinase values were seen at 18 months postinfection (mean 9838, SD 4805 U/L) compared to preinfection (mean 950, SD 374 U/L). Needle EMG studies revealed abnormal spontaneous activity in 2 cats. All FIV-MD infected cats exhibited at least one abnormality in muscle pathology. Of the 24 muscle samples, 15 (63%) had histopathologic lesions. The predominant histologic abnormalities consisted of perivascular and pericapillary lymphocytic infiltration, and myofiber necrosis, phagocytosis, and regeneration. Lymphocytic infiltration was graded 2+ or higher in 12 of 24 muscle samples (0 = negligible; 4+ = extensive). Immunohistochemical phenotypic lymphocyte labeling in all cats demonstrated only CD8+ lymphocyte staining. This report demonstrates the presence of a FIV associated inflammatory myopathy in the adult cat. Several similarities are apparent in comparison to HIV-1 associated polymyositis reported in humans. Future studies in the cat may thus prove useful in elucidating the pathogenesis of retrovirus related myopathy in humans. © 1998 John Wiley & Sons, Inc. Muscle Nerve 21: 1680–1685, 1998

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