Myosin heavy-chain myopathy in 2 American quarter horses. Academic Article uri icon

abstract

  • A 1.5-year-old American quarter horse gelding (case 1) and an 11-month-old American quarter horse filly (case 2) were presented for acute onset pelvic lameness and lethargy. Case 1 had nasal discharge, while case 2 developed rapid muscle atrophy. Both horses had elevated serum creatine kinase activity. The horses showed similar polyphasic histiocytic and lymphoplasmacytic myositis with necrosis, mineralization, and regeneration. Additionally, case 1 had Streptococcus equi subsp. equi-induced suppurative retropharyngeal lymphadenitis with renal purpura hemorrhagica and myoglobinuric nephropathy. A focal pulmonary abscess caused by Actinobacillus equuli was found in case 2. Genetic testing revealed case 1 as heterozygous and case 2 as homozygous for the E321G MYH1 variant, supporting the diagnosis of myosin heavy-chain myopathy, with concomitant bacterial disease as potential triggers.

published proceedings

  • Vet Pathol

author list (cited authors)

  • Faccin, M., Landsgaard, K. A., Milliron, S. M., Jennings, A. H., Keith Chaffin, M., Giaretta, P. R., & Rech, R. R.

citation count

  • 0

publication date

  • October 2023