Muscular Dystrophy

• Inherited group of degenerative muscular diseases
• Progressive muscle weakness and wasting
• Usually due to a genetic fault -> muscular protein deficiency
  • Duchenne MD in humans due to dystrophin deficiency also present in some animals
  • Dystrophin gene mutations reported in the Golden Retriever, Rottweiler, German shorthaired pointer and Irish terrier etc.
• Inadequate regeneration, compensatory hypertrophy

More about muscular dystrophy

• Reported in a Rat terrier
  • V high creatine kinase levels, high ALT
  • Hypertrophic and atrophic skeletal muscle fibres
  • Necrosis, degeneration, phagocytosis, etc seen in the muscle
  • Rare myofibre splitting into 2 or more daughter fibres (see on cross section as round fibre, split into two D-shaped halves)
  • No dystrophin detected
• Mutation in dystrophin gene
  • Cytoplasmic side of the myofibre plasma membrane – playing a role in membrane stability and integrity
  • Due to increased membrane permeability  Ca2+enters and CK leaks out.
• X-linked MD in Golden retrievers, also suspected in Irish terriers, Belgian Groenendaels, Samoyeds, minature schnauzers and Brittany spaniels
• In cats – hypertrophic muscular dystrophy – no dystrophin detected either
• Diaphram, tongue and oesophagus usually particularly hypertrophied
• No major rearrangements/deletions of promotor region of the dystrophin gene in cases of dilated cardiomyopathy in Dobermans and Irish terrier myopathy