Ive just noticed on my older Bitches back paw half of her pad has turned into hair type substance. I googled this and it says later stages of hard pad canine distemper for this symptom. She was started on new vaccinations two weeks ago as i noticed she was overdue. She is due again mon. Panicking now please say it could be something else. Not sure if to take her to emergency vet. Anyone awake with advice?

Without seeing what you are describing it would be impossible to be able to say with any certainty what it is over the net

However,
One thing I do know, if it was a sign/symptom of distemper she would have other more worrying signs and be very unwell   If she is otherwise well I wouldn't panic at this stage maybe a call to the vet and arrange a visit on Monday?   Of course if she IS UNWELL then yes emergency vet 

Hyperkeratosis - if this is what you are seeing - can have a number of different causes, my first guess would be a combination of her size/weight (if she's one of your Danes and exercising on rough/hard ground

Hope this helps