Rigor Mortis

• Muscles remain biochemically active after the death of an animal
• Following a period of relaxation, contraction and stiffening occurs
• Due to deficiency of ATP releasing myosin heads from their binding sites at end of power stroke
• Onset faster in ATP deprived animals (starvation, hunting, tetanus...)
• May be absent in cachetic animals
• Disappears due to autolysis or putrefaction
• See general pathology

• • Damage occured at one time, e.g. trauma or one toxin exposure
• Multiphasic lesions - different stages as described above
  • Ongoing damage, e.g. vitamin E - selenium deficiency, continuous exposure to toxin