Equine muscular dystrophy with myotonia.

Abstract

OBJECTIVES:

To describe a case of equine muscular dystrophy with myotonia.

METHODS:

A 5-year-old horse presented with hypertrophy and delayed relaxation of the muscles of the hindlimbs from age 2 months. Testicular atrophy developed from 2 years of age. Action and percussion myotonia was associated with weakness in these muscles, and EMG showed diffuse myotonic discharges and myopathic features. Biopsy of the gluteal muscle showed adipose and connective tissue infiltration, marked variation in muscle fibre size, and moth-eaten, ring and whorled fibres.

RESULTS:

Injection of apamin, a peptide blocker of calcium-activated potassium channels, which inhibits myotonia in human myotonic dystrophy, was ineffective in blocking myotonic discharges. Discharges promptly abated with 2% lidocaine injection.

CONCLUSIONS:

Myotonia in this horse is associated with dystrophic changes similar to human myotonic dystrophy, though there are some pharmacological differences.

• Authors: P Montagna, R Liguori, L Monari, P N Strong, R Riva, V Di Stasi, G Gandini, M Cipone
• Journal: Clinical neurophysiology : official journal of the International Federation of Clinical Neurophysiology (Clin Neurophysiol) Vol. 112 Issue 2 Pg. 294-9 (Feb 2001) ISSN: 1388-2457 [Print] Netherlands
• PMID: 11165532 (Publication Type: Journal Article)

Chemical References

• Anesthetics, Local
• Apamin
• Lidocaine

Topics

• Anesthetics, Local (therapeutic use)
• Animals
• Apamin (therapeutic use)
• Atrophy
• Electromyography
• Hindlimb
• Horse Diseases (drug therapy, pathology, physiopathology)
• Horses
• Hypertrophy
• Lidocaine (therapeutic use)
• Male
• Muscle Relaxation
• Muscle Weakness (etiology)
• Muscle, Skeletal (drug effects, pathology, physiopathology)
• Muscular Dystrophy, Animal (complications, drug therapy, pathology, physiopathology)
• Myotonia (complications, drug therapy, physiopathology, veterinary)
• Neural Conduction
• Testis (pathology)
• Treatment Failure