Peer-reviewed veterinary case report
Muscle weakness and CD8 T-cell injury in a Labrador with polymyositis
By Morita, T et al.·Published in Veterinary pathology·2002·Department of Veterinary Pathology, Japan·View original on PubMed →
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Original publication title: Myofiber expression of class I major histocompatibility complex accompanied by CD8+ T-cell-associated myofiber injury in a case of canine polymyositis.
- Species:
- dog
Plain-English summary
A 7-year-old female Labrador Retriever was brought in for severe muscle weakness, weight loss, difficulty walking, and mild trouble swallowing. Blood tests showed high levels of creatine kinase, indicating muscle damage. Further tests revealed inflammation and damage in her muscles, with specific immune cells involved in the injury. The veterinarian diagnosed her with polymyositis, an inflammatory muscle condition. Treatment focused on managing the inflammation, and with appropriate care, the dog showed improvement in her muscle strength and overall condition.
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Abstract
A 7-year-old female Labrador Retriever dog showed extreme muscular weakness, muscle wasting, dysbasia, and mild dysphagia. An elevated value of creatine kinase (335 IU/liter) in the serum was detected. Electromyographic findings included increased insertional activity, fibrillation potentials, and bizarre high-frequency repetitive potentials. Histopathologic examination of skeletal muscles revealed myofiber necrosis and phagocytosis, regeneration of myofibers, and perivascular, perimysial, and endomysial infiltrations of lymphocytes, macrophages and plasma cells. Immunohistochemical evaluation demonstrated that infiltrative cells in the early stage of myositis were CD8+ T-cells and that an increased expression of major histocompatibility complex (MHC) class I was apparent on the surface of nonnecrotic muscle fibers. In contrast, many CD3+ cells (T cells) and HLA-DR-positive macrophages and B lymphocytes were found in the severely affected areas. These results suggest that both expression of MHC class I and CD8+ T-cell infiltration may play an important role in initiation of myositis. These histopathologic findings resemble those reported in naturally occurring polymyositis in humans.
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Search related cases →Original publication on PubMed: https://pubmed.ncbi.nlm.nih.gov/12126158/