Merck Manual

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Differential Diagnoses of Equine Myopathies

Differential Diagnoses of Equine Myopathies

Non-exercise-associated Rhabdomyolysis

Inflammatory myopathies

Clostridial myositis

Influenza myositis

Sarcocystis myositis

Immune-mediated myopathy

Nutritional myopathy

Vitamin E and selenium deficiency

Toxic myopathies

Ionophore toxicity

Senna occidentalis

Pasture myopathies

Rayless goldenrod/white snakeroot

Hypoglycin A in box elder and European sycamore trees

Traumatic myopathies

Compressive anesthetic myopathy

Trauma

Genetic myopathies

Glycogen branching enzyme deficiency in Quarter horses

Polysaccharide storage myopathy types 1 and 2

Malignant hyperthermia in Quarter horses

Exertional Rhabdomyolysis

Focal muscle strain

Sporadic tying-up (overexertion)

Chronic tying-up

Dietary imbalances, vitamins, minerals, electrolytes

Polysaccharide storage myopathy types 1 and 2

Malignant hyperthermia

Recurrent exertional rhabdomyolysis

Idiopathic chronic exertional rhabdomyolysis

Exertional Myopathy with Normal CK

Mitochondrial myopathy

Polysaccharide storage myopathy type 2

Muscle Atrophy

Myogenic atrophy

Severe rhabdomyolysis

Disuse

Cushing disease

Immune-mediated myositis (rapid atrophy)

Vitamin E–deficient myopathy

Homozygous polysaccharide storage myopathy type 1

Polysaccharide storage myopathy type 2

Neurogenic atrophy

Equine protozoal myelitis

Local nerve trauma

Equine motor neuron disease

Idiopathic peripheral neuropathy

Toxic peripheral neuropathies

Muscle Fasciculations

Pain, fear

Weakness (botulism, chronic debilitation)

Electrolyte abnormalities

Equine motor neuron disease

Hyperkalemic periodic paralysis

Hypokalemia

Otobius megnini (ear tick) infestation

Myotonic dystrophy

Stiff horse syndrome

Shivers