ISSN 2398-2977      

Muscle: myopathy - overview


Synonym(s): Muscle myopathy




  • Neurogenic or myogenic.
  • A field of considerable recent and ongoing research.
  • Some syndromes are multifactorial and difficult to specifically define etiology.

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.


Post-anesthetic myopathy Muscle: myopathy - postanesthetic

Exertional rhabdomyolysis Muscle: myopathy - exertional rhabdomyolysis 

  • Multifactorial: irregular exercise, dietary imbalances, possibly genetic in some individuals.

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 

  • Ingestion of toxin hypoglycin A found in seeds, leaves and seedlings of trees of the genus Acer (maples). In UK, Acer pseudoplatanus, and in North America Acer negundo.
  • Associated with stressful environmental conditions and low plane of nutrition.

White muscle disease of foals Nutrition: nutritional myopathy 

  • Selenium deficiency plus as yet unknown factors → failure to protect muscle cell membranes from peroxidative damage.


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Further Reading


Refereed papers

  • Recent references from PubMed and VetMedResource.
  • Valberg S J (2020) Genetics of equine muscle disease. Vet Clin North Am Equine Pract 36 (2), 353-378 PubMed.
  • Noll C V (2019) Standing myotomy to treat fibrotic myopathy: 22 cases (2004-2016) Vet Surg 48 (6), 997-1004 PubMed.
  • Valberg S J (2018) Muscle conditions affecting sport horses. Vet Clin North Am Equine Pract 34 (2), 253-276 PubMed.
  • Durward-Akhurst S A & Valberg S J (2018) Immune-mediated muscle diseases of the horse. Vet Pathol 55 (1), 68-75 PubMed.
  • Lewis S S et al (2017) Clinical characteristics and muscle glycogen concentrations in warmblood horses with polysaccharide storage myopathy. Am J Vet Res 78 (11), 1305-1312 PubMed.
  • Gonzalez-Medina, S et al (2017) Equine atypical myopathy in the UK: Epidemiological characteristics of cases reported from 2011 to 2015 and factors associated with survival. Equine Vet J 49 (6), 746-752 PubMed.
  • Valberg S J et al (2016) Suspected myofibrillar myopathy in Arabian horses with a history of exertional rhabdomyolysis. Equine Vet J 48 (5), 548-56 PubMed.
  • Naylor R (2016) Atypical myopathy - insights on pathogenesis. Equine Vet J 48 (4), 401-402 PubMed.
  • Gonzalez-Medina S (2015) Update on the cause of equine atypical myopathy. Vet Rec 176 (6), 143-5 PubMed.
  • Van Driessche K et al (2015) Ultrastructural mitochondrial alterations in equine myopathies of unknown origin. Vet Q 35 (1), 2-8 PubMed.
  • 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.
  • Lofstedt J (1997) White muscle disease of foals. Vet Clin North Am Equine Pract 13, 169-185 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.

Related Images


Anesthesia: analgesia - overview

Anesthesia: monitoring - cardiac output and blood pressure

Anesthesia: standing chemical restraint

Anesthesia: ventilators - overview

Atypical myoglobinuria

Blood: biochemistry - aspartate amino transferase (AST)

Blood: biochemistry - creatine kinase

Blood: biochemistry - creatinine

Blood: biochemistry - lactate dehydrogenase

Blood: biochemistry - potassium

Blood: biochemistry - urea

Bone: scintigraphy


Cardiovascular: aortoiliac thrombosis

Clostridia spp

CSF: creatine kinase

Electrodiagnostic testing

Equine herpesvirus

Equine influenza virus

Fluid therapy: electrolyte abnormalities

Fluid therapy: overview


Hindlimb: radiography

Immune-mediated disease: overview

Irish Draught

Kidney: renal failure


Malignant hyperthermia

Muscle: biopsy

Muscle: glycogen branching enzyme deficiency (GBED)

Muscle: hyperkalemic periodic paralysis

Muscle: myopathy - atypical

Muscle: myopathy - fibrotic

Muscle: myopathy - postanesthetic

Muscle: myopathy - sporadic exertional rhabdomyolysis

Musculoskeletal: exercise response test

Musculoskeletal: nutritional deficiencies

Musculoskeletal: physiotherapy

Neurology: motor neuron disease

Neurology: shivering

Nutrition: energy

Nutrition: minerals

Nutrition: nutritional myopathy

Peripheral nerve: trauma


Respiratory: endoscopy

Sarcocystis neurona


Staphylococcus spp

Streptococcus spp


Therapeutics: anti-inflammatory drugs

Therapeutics: antimicrobials



Toxicity: methylxanthine

Ultrasonography: overview

Urine: overview

Vitamin B1

Vitamin E

Weight loss: overview

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