Myosin heavy-chain myopathy in 2 American quarter horses.
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.
Publication Date: 2023-10-11 PubMed ID: 37818977DOI: 10.1177/03009858231204253Google Scholar: Lookup
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Summary
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The research article discusses a case study of two American quarter horses diagnosed with Myosin heavy-chain myopathy, a muscular disease, also showing symptoms of bacterial infections which potentially triggered the condition.
Case Identifications
- The study involved two American quarter horses – a 1.5-year-old male (Case 1) and an 11-month-old female (Case 2).
- Both animals were identified due to symptoms of sudden pelvic lameness and lethargy.
Symptoms and Conditions
- Case 1 exhibited nasal discharge while Case 2 suffered from rapid muscle atrophy.
- Both horses displayed raised serum creatine kinase activity levels – a sign indicative of muscle damage.
- Unique conditions associated with each case were observed. Case 1 was found to have suppurative retropharyngeal lymphadenitis with renal purpura hemorrhagica and myoglobinuric nephropathy, likely caused by Streptococcus equi. In Case 2, a focal pulmonary abscess possibly caused by Rhodococcus equi was noticed.
Genetic Testing and Diagnosis
- Genetic tests on both horses resulted in the discovery of the E321G MYH1 variant in their DNA.
- The presence of this genetic variant confirmed the diagnosis of Myosin heavy-chain myopathy.
Final Conclusions
- Co-existing bacterial infections in the two horses are theorized to act as possible triggers for the identified myopathy.
- This research emphasizes the possible linkage between bacterial diseases and the onset of muscular diseases in horses like the Myosin heavy-chain myopathy.
Cite This Article
APA
Faccin M, Landsgaard KA, Milliron SM, Jennings AH, Keith Chaffin M, Giaretta PR, Rech RR.
(2023).
Myosin heavy-chain myopathy in 2 American quarter horses.
Vet Pathol, 61(3), 462-467.
https://doi.org/10.1177/03009858231204253 Publication
Researcher Affiliations
- Texas A&M University, College Station, TX.
- Texas A&M University, College Station, TX.
- Texas A&M University, College Station, TX.
- Texas A&M University, College Station, TX.
- Texas A&M University, College Station, TX.
- Texas A&M University, College Station, TX.
- Texas A&M University, College Station, TX.
MeSH Terms
- Animals
- Horses
- Horse Diseases / pathology
- Horse Diseases / microbiology
- Horse Diseases / diagnosis
- Myosin Heavy Chains / genetics
- Male
- Muscular Diseases / veterinary
- Muscular Diseases / pathology
- Muscular Diseases / genetics
- Female
- Streptococcal Infections / veterinary
- Streptococcal Infections / pathology
- Streptococcus equi / genetics
- Streptococcus equi / isolation & purification
- Muscle, Skeletal / pathology
Conflict of Interest Statement
Declaration of Conflicting InterestsThe author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.
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