ISSN 2398-2977      

Muscle: myopathy - overview

pequis

Synonym(s): Muscle myopathy


Introduction

  • Cause: neurogenic: hereditary or environmental, acquired or congenital; myogenic: trauma, inflammatory, infectious, toxic, hormonal, circulatory, genetic, nutritional, exercise-related, cachectic, malignancy, disuse.
  • Signs: muscle cramps on exercise, gait abnormality, muscle weakness, tremor, local or generalized muscle dysfunction; pain and associated systemic signs, eg colic, increased heart and respiratory rates increased body temperature; local swellings; muscle wastage; myoglobinuria, recumbency, sudden death.
  • Diagnosis: physical examination, exercise tests, biochemical tests, genetic tests, diagnostic imaging (thermography, electromyography, scintigraphy, ultrasonography), muscle biopsy.
  • Treatment: symptomatic and supportive, eg analgesia, sedation, fluid therapy; specific, eg diet and exercise, surgery.
  • Prognosis: depends on etiology and severity; generally guarded.
  • Myopathies include:

Pathogenesis

Etiology

  • Neurogenic or myogenic.
  • A field of considerable ongoing research.
  • A firm etiologic basis for many causes of rhabdomyolysis has yet to be described.
  • Evidence is emerging for 3 immune-mediated syndromes: severe rhabdomyolysis and infarctive purpura (both associated withStreptococcus equi  Streptococcus spp  exposure) and immune-mediated polymyositis of Quarterhorses.

Neurogenic(hereditary or environmental, acquired or congenital)

  • Peripheral neuropathies.
  • Neuromuscular transmission disorders, eg Botulism   Botulism  , Tetanus   Tetanus  .
  • Anterior horn cell disorders.
  • Motor nerve root disorders.

Myogenic

Post-anesthetic myopathy  Muscle: myopathy - postanesthetic 

Exertional rhabdomyolysis  Muscle: myopathy - exertional rhabdomyolysis 

  • Multifactorial: irregular exercise, dietary imbalances, hormonal, metabolic.

Hyperkalemic periodic paralysis  Muscle: hyperkalemic periodic paralysis 

  • Genetic defect   →   abnormality in sodium channel transport.

Fibrotic and ossifying myopathy  Muscle: myopathy - fibrotic 

  • Trauma to semitendinosis   →   contracture.

Atypical myoglobinuria  Atypical myoglobinuria 

  • Unknown.
  • Associated with stressful environmental conditions and low plane of nutrition.

White muscle disease of foals  Nutrition: nutritional myopathy 

  • Selenium deficiency   →   failure to protect muscle cell membranes from peroxidative damage.

Storage myopathy  Muscle: myopathy - exertional rhabdomyolysis 

  • Glycogen and polysaccharide accumulation in muscle due to excessive synthesis.
  • Signs similar to exertional rhabdomyolysis.
  • Recurrent attacks.

Diagnosis

This article is available in full to registered subscribers

Sign up now to obtain ten tokens to view any ten Vetlexicon articles, images, sounds or videos, or Login

Treatment

This article is available in full to registered subscribers

Sign up now to obtain ten tokens to view any ten Vetlexicon articles, images, sounds or videos, or Login

Outcomes

This article is available in full to registered subscribers

Sign up now to obtain ten tokens to view any ten Vetlexicon articles, images, sounds or videos, or Login

Further Reading

Publications

Refereed papers

  • Recent references from PubMed and VetMedResource.
  • Naylor R (2014) Managing muscle disease is horses. In Pract 36 (8), 418-423 BMJ.
  • Baird J D, Valberg S J, Anderson S M et al (2010) Presence of the glycogen synthase 1 (GYS1) mutation causing type 1 polysaccharide storage myopathy in continental European draught horse breeds. Vet Rec 167 (20), 781-784 PubMed.
  • Winjberg I D, Ruitenbeek W, Jansen G et al (2008) Myopathy in a Haflinger horse: An initiating search for a fatty acid oxidation deficiency. Equine Vet Educ 20 (10), 532-538 WileyBlackwell.
  • Hunt L M, Valberg S J, Steffenhagen K & McCue M E (2008) An epidemiological study of myopathies in Warmblood horses. Equine Vet J 40 (2), 171-177 PubMed.
  • Vercauteren G, van der Heyden S, Lefere L et al (2007) Concurrent atypical myopathy and equine dysautonomia in two horses. Equine Vet J 39 (5), 463-465 PubMed.
  • Franci P, Leece E A & Brearley J C (2006) Post anesthetic myopathy/neuropathy in horses undergoing magnetic resonance imaging compared to horses undergoing surgery. Equine Vet J 38 (6), 497-501 PubMed.
  • Aupperle H, Borgel C, Raila G & Schoon H-A (2004) Morphological, immunohistochemical and ultrastructural findings in an embryonal rhabdomyosarcoma of a newborn Thoroughbred foal. J Equine Vet Sci 24 (4), 159-164 VetMedResource.
  • Hahn C N (2003) Equine myopathies. Equine Vet Educ 15 (4), 188-189 WileyBlackwell.
  • Valberg S J et al (1998) Skeletal muscle metabolic response to exercise in horses with 'tying-up' due to polysaccharide storage myopathy. Equine Vet J 31, 43-47 (Defines the metabolic events in exertional rhabdomyolysis caused by storage disease) PubMed.
  • Lofstedt J (1997) White muscle disease of foals. Vet Clin N Am Equine Practice 13, 169-185 PubMed.
  • Robinson H C (1991) Atypical myoglobinuria. Vet Rec 128, 166 PubMed.
  • Harris P et al (1990) Atypical myoglobinuria alert. Vet Rec 127, 603 PubMed.
  • Whitwell K E et al (1988) Atypical myoglobinuria - an acute myopathy in grazing horses. Equine Vet J 20, 357-363 PubMed.
  • Bramlage L R, Reed S M & Embertson R M (1985) Semitendinosus tenotomy for treatment of fibrotic myopathy in the horse. JAVMA 186, 565-567 PubMed.

Other sources of information

  • Various Authors (2005) Endurance and Sports Horse Session. In: Handbook of Presentations and Free Communications BEVA Congress 2005. Equine Veterinary Journal Ltd., UK. pp 78, 83, 86, 99.
  • MacLeay J M (2004) Diseases of the Musculoskeletal System. In: Equine Internal Medicine. Eds: Reed S M, Bayly W M & Sellon D C. Saunders, USA. pp 469-522.

Related Images

Can’t find what you’re looking for?

We have an ever growing content library on Vetlexicon so if you ever find we haven't covered something that you need please fill in the form below and let us know!