Multiple acyl-CoA dehydrogenase deficiency

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Multiple Acyl-CoA Dehydrogenase Deficiency

Equine MADD, Glutaric Acidemia Type II (GA-II)

Equine multiple acyl-CoA dehydrogenase deficiency (MADD) is a type of muscle disorder (a metabolic myopathy) of horses, which results from a biochemical defect of the skeletal muscle energy system. There are three general forms of MADD:
  • Neonatal-onset form w/ congenital anomalies
  • Neonatal-onset form without congenital anomalies
  • Late-onset form (ethylmalonic-adipic aciduria)
Equine MADD is a disorder of the horse's fatty acid and protein metabolism. It is caused by a defect of the horse's electron transfer flavoproteins that catalyze the various electro-transferring reactions in energy production, biosyntheis, detoxification, and electron-scavenging pathways. There are a wide range of clinical signs and age at presentation of late-onset MADD.


Stiff, insecure gait
Straddle-legged gait
Extremely firm muscles


  • History
  • Clinical signs
  • Physical exam
  • Histopathology
  • Analysis of plasma selenium levels



Nutritional managementChanging the horse to a low-protein, low-fat, high-carbohydrate diet with multiple feeding intervals avoiding long periods of fasting.
Oral supplementsAdding additional riboflavin, carnitine, or glycine to the diet


Scientific Research

General Overviews

Risk Factors

  • Seasonal pasture myopathy
  • Selenium deficiency
  • Deficiency in riboflavin (vitamin B2), which may contribute to or cause muscle myopathy in horses.