what is a ''prepatched'' dread
You already asked in several threads.
PP just means it spawned before patch97 , when Broadsword didnt lower the baseline stats of pets.
Since there are no freshly spawned dreadmares for many many years. All dreadmares can be considered prepatch.
If they ever added them back, you could talk about non-PP dreadmare, but it's up to Broadsword if they would adjust the stats or not in that case.