Nemaline myopathy in a six-month-old Pomeranian dog

Authors

Keywords:

canine, congenital, Gomori trichrome, histopathology, Masson trichrome, nemaline myopathy, ultrastructure

Abstract

Nemaline myopathy – a clinically and genetically complex heterogenous group of disorders – is described uncommonly in humans and rarely in animals, and is characterised by progressive muscle weakness. The diagnosis is confirmed by histological and/or ultrastructural identification of subsarcolemmal, thread-like, rod-shaped structures called nemaline rod bodies within more than 40% of skeletal muscle fibres. These rods contain the Z-line protein, α-actinin, that can be effectively stained in skeletal muscle using Gomori or Masson trichrome and negatively stained with periodic acid-Schiff. Similar rod-like bodies have been found in smaller numbers in dogs with endocrine disorders and occasionally in other conditions in humans. This report is of a six-monthold Pomeranian dog which had progressive exercise intolerance over a two-month period associated with severe disuse muscle atrophy of the thoracic limbs, as well as gradual pelvic limb weakness and regurgitation of food. Baseline diagnostics ruled out endocrinopathies and after histological and ultrastructural evaluation of thoracic limb muscles and nerve biopsies confirmed nemaline myopathy. The clinical course, diagnostic test results, ultrastructure of skeletal muscle and peripheral nerve, gross necropsy findings and histopathology using various stains are described and illustrated.

Author Biographies

E G Bester, University of Pretoria

Department of Companion Animal Clinical Studies, Faculty of Veterinary Science, University of Pretoria, South Africa

A M Kitshoff, University of Pretoria

Department of Companion Animal Clinical Studies, Faculty of Veterinary Science, University of Pretoria, South Africa

W J Botha, Panorama Veterinary Clinic and Specialist Centre

Department of Small Animal Medicine Clinic, Panorama Veterinary Clinic and Specialist Centre, South Africa

E van Wilpe, University of Pretoria

Laboratory for Microscopy and Microanalysis, Faculty of Natural and Agricultural Sciences, University of Pretoria, South Africa

L Du Plessis, University of Pretoria

Electron Microscope Unit, Department of Anatomy and Physiology, Faculty of Veterinary Science, University of Pretoria, South Africa

J Williams, University of Pretoria

Section of Pathology, Department of Paraclinical Sciences, Faculty of Veterinary Science, University of Pretoria, South Africa

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Published

2022-04-19

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Section

Original Research