Equis ISSN 2398-2977

Heart: cardiomyopathy

Contributor(s): Christopher Brown, Vetstream Ltd, Lesley Young

Introduction

  • Cause: idiopathic, drugs, viral, immune-mediated, nutritional.
  • Signs: depend on severity of myocardial dysfunction.
  • Diagnosis: echocardiography.
  • Treatment: rest, drugs to prevent arrhythmias, eg digoxin, diuretics eg furosemide.
  • Prognosis: poor.

Pathogenesis

Etiology

  • Ionophore antibiotics eg monensin, salininomycin. These are used as growth promoters in cattle feeds and as coccidiostats in poultry feed. Found when cattle feed is accidentally fed to horses or there is inadvertent contamination at a feed mill. Specialist feed analysis required. The drugs cause acute cellular necrosis; the liver, kidneys and skeletal muscle may also be affected.
  • Nutritional causes leading to vitamin E and selenium deficency are not commonly seen in the UK. Occasionally seen in foals with malnourished dams or in parts of the world where there is mineral imbalance in the soil. Skeletal muscle is usually affected concurrently. Vitamin D toxicity has also been reported as a cause of cardiomyopathy when there is over supplementation, or access to toxic plants.
  • Viral or immune-mediated.
  • Idiopathic.

Pathophysiology

  • Poor myocardial contractility leads to low output failure.
  • Cardiac enlargement and areas of damaged myocardium predispose to arrhythmias and results in poor ventricular filling and cardiac inefficiency.

Diagnosis

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Treatment

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Outcomes

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Further Reading

Publications

Refereed papers

  • Recent references from PubMed and VetMedResource.
  • Freel K M, Morrison L R, Thompson H & Else R W (2010)Arrhythmogenic right ventricular cardiomyopathy as a cause of unexpected cardiac death in two horses.Vet Rec166(23), 718-722 PubMed.
  • Wijnberg I Det al(1998)Atrial fibrillation associated with central nervous symptoms and colic in a horse, a case of equine cardiomyopathy.Vet Q20(2), 73-76 PubMed.
  • Traub-Dargatz J Let al(1994)Ventricular tachycardia and myocardial dysfunction in a horse.JAVMA205(11), 1569-1573 PubMed.
  • Cranley J Jet al(1981)Ischemic myocardial fibrosis and aortic strongylosis in the horse.Equine Vet J13(1), 35-42 PubMed.
  • Hadlow W Jet al(1974)Myopathies of animals - a brief view.Adv Cardiol13, 68-80 PubMed.


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