Equine Rhabdomyolysis

  • Azoturia (Monday morning disease)
    • Acute
    • Due to exercise following a prolonged period of rest
    • Clincal signs:
      • Unable to move
      • Sweating
      • Tremors
      • Swollen and hard lumbar, gluteal and femoral muscles
    • Myoglobin leaks from muscle cells -> leaks into urine -> urine is dark red/brown (myoglobinuria) -> damages renal tubules
    • Grossly:
      • Salmon pink muscles -> dark, moist, swollen +/- pale streaks
    • Histologically:
      • Segmental myofibre necrosis
        • Multifocal and monophasic, but may be multiphasic if repeated bouts
      • Both, type IIA and IIB fibres affected; type IIB preferentially affected in acute disease
      • Minor inflammatory reaction and calcification
  • Tying-up
    • Similar to azoturia but much milder
    • Grossly - normal muscle
    • Histologically - same as azoturia