Myopathy happens when a kangaroo is under extreme stress, as is the case when it is being attacked or chased by a dog.
They do not have to be injured directly to develop myopathy, which is a disintegration of the muscle fibres. From within 24 hours up to a few weeks after the incident, they will show stiffness and paralysis mainly in the hindquarters, progressing to complete paralysis, it will also salivate excessively, death will occur within 2-14 days after the stressful incident.
Usually we will not see the kangaroo in this state, as it will go somewhere quiet and out of sight to die.
It is natural for us to think that if the dog did not catch the kangaroo, no harm has been done, the dog had a good run, the kangaroo got away. As you have just read, the kangaroo may have gotten away, but it did not escape a painful and slow death.
It is very unfortunate that this situation takes place on a regular basis in the country, as it is avoidable, just by locking up your dog at night when most Australian native animals are most active.
Be alert to what is taking place around you, especially at night, and help our native animals survive in an ever diminishing natural environment.