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Cytologic and Histopathologic Evaluation of Extruded Canine Degenerate Disks

Authors

  • ANGELA B. ROYAL DVM, MS,

    1. Departments of Veterinary Pathobiology and Medicine and Surgery, University of Missouri College of Veterinary Medicine, Columbia, MO.
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  • MUNASHE CHIGERWE BVSc, Diplomate ACVIM (Large Animal),

    1. Departments of Veterinary Pathobiology and Medicine and Surgery, University of Missouri College of Veterinary Medicine, Columbia, MO.
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  • JOAN R. COATES DVM, MS, Diplomate ACVIM (Neurology),

    1. Departments of Veterinary Pathobiology and Medicine and Surgery, University of Missouri College of Veterinary Medicine, Columbia, MO.
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  • CHARLES E. WIEDMEYER DVM, PhD, Diplomate ACVP (Clinical Pathology),

    1. Departments of Veterinary Pathobiology and Medicine and Surgery, University of Missouri College of Veterinary Medicine, Columbia, MO.
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  • LINDA M. BERENT DVM, PhD, Diplomate ACVP (Clinical and Anatomic Pathology)

    1. Departments of Veterinary Pathobiology and Medicine and Surgery, University of Missouri College of Veterinary Medicine, Columbia, MO.
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  • Partially funded by a grant from the Pi Chapter of the Phi Zeta Veterinary Honor Society.

  • Presented in part at the American Society for Veterinary Clinical Pathology 42nd annual meeting, Savannah, GA, November 10–14, 2007 (abstract published in Veterinary Clinical Pathology 36: 315, 2007).

Corresponding author: Dr. Angela B. Royal, DVM, MS, Department of Veterinary Pathobiology, University of Missouri College of Veterinary Medicine, B202 Clydesdale Hall, 900 E. Campus Drive, Columbia, MO 65211. E-mail: royalab@missouri.edu.

Abstract

Objective— To describe the cytologic and histopathologic appearance of degenerate disk material in dogs with Hansen type I intervertebral disk disease (IVDD).

Study Design— Case series.

Animals— Dogs (n=45) that had surgical intervention for Hansen type I IVDD (January–November 2007).

Methods— Impression smears and histopathologic sections were prepared from surgically removed degenerate disk material. All slides were evaluated for overall cellularity, quantity and attributes of extracellular matrix, types of cells present, and their cytomorphology. Histopathologic sections were also examined for presence of neovascularization and hemorrhage.

Results— Cytologically, 11 of 45 samples consisted of only extracellular matrix, 30 had evidence of inflammation, and 20 contained dysplastic spindloid cells. Histologically, hyaline cartilage predominated in 35 of 45 samples, fibrocartilage in 4, and spindloid cells in 6; 37 of 45 were inflamed, 37 were hemorrhagic, and 13 had neovascularization.

Conclusions— The cytologic and histopathologic appearance of extruded degenerate disk material in dogs is variable and can include dysplastic spindloid cells.

Clinical Relevance— The variability in cytologic findings and frequent presence of dysplastic spindloid cells suggest that cytology alone may not be a reliable tool to differentiate degenerate canine disk material from a mesenchymal neoplasm.

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