Canine Inflammatory Myopathies: A Clinicopathologic Review of 200 Cases

Abstract

A retrospective study was performed on 200 randomly selected cases of inflammatory myopathy in dogs from diagnostic muscle biopsies received at the Comparative Neuromuscular Laboratory, University of California, San Diego. The most common clinical signs in dogs diagnosed with an inflammatory myopathy were generalized weakness, stilted gait, dysphagia, masticatory or generalized muscle atrophy, inability to open the jaw, megaesophagus, and dysphonia. Myalgia was rarely described. Age of onset ranged from 0.25 to 14 years. Genders were equally represented. Breed distribution approximated the 2002 American Kennel Club registration statistics (r .85) with the notable exception of Boxers and Newfoundlands. From the results of muscle biopsies, clinical signs, and presence or absence of antibodies against type 2M fibers, dogs were classified as a generalized inflammatory myopathy (gIM)-including immune-mediated polymyositis; infectious and preneoplastic myositis; and, rarely, dermatomyositislike or overlap syndromes or unclassified myositis-or a focal inflammatory myopathy (fIM)-including masticatory muscle and ex-traocular myositis. Average creatine kinase (CK) and aspartate aminotransferase (AST) concentrations in gIMs were significantly higher than those with fIMs (P .05). Neoplasia developed in 12 of 200 dogs within 12 months of diagnosis of polymyositis, with lymphoma diagnosed in 6 of 32 Boxers. Inflammatory myopathy was associated with antibody titers against infectious diseases in 38 dogs. Neospora caninum and Hepatozoon americanum cysts were found in tissues of 2 dogs not serologically tested. Antibodies against an unidentified sarcolemmal antigen were found in 9 of 19 Newfoundlands with polymyositis. The spectrum of canine inflammatory myopathies can be broad, with infectious etiologies relatively common, and can include preneoplastic and uncharacterized syndromes.

Autoantibodies in Canine Masticatory Muscle Myositis Recognize a Novel Myosin Binding Protein-C Family Member

“…Spontaneous IMs occur in dogs (7)(8)(9)(10)(11)(12)(13)(14)(15)(16), and canine IMs may provide good parallels and insights into human IMs (17). In a clinicopathologic review of 200 cases of canine IM (8), a spectrum of clinical forms was identified, including polymyositis, dermatomyositis, and masticatory muscle myositis.…”

“…In a clinicopathologic review of 200 cases of canine IM (8), a spectrum of clinical forms was identified, including polymyositis, dermatomyositis, and masticatory muscle myositis. To date, a canine homologue of inclusion body myositis has not been identified.…”

Myofasciitis in the Domestic Ferret

“…Necropsies of case Nos. [1][2][3][4][5][6][7][8][9][10][11][12] were performed at referring clinics and case Nos. 14-17 at NZP.…”

“…Moderate to severe suppurative to pyogranulomatous inflammation was in the skeletal muscle and the fascia of the esophagus (18), the heart (18), and the muscles of the hind limbs or the lumbar region (11), and in front limbs, head, sternum, and abdominal wall of cases (case Nos. [13][14][15][16][17].…”

“…11,23 The most common myopathies occurring in humans include polymyositis (PM), inclusion body myositis (IBM), and dermatomyositis (DM). 8,25 Canine models of DM and PM also exist.…”