I can really relate to the problem with running monsters and slow pets. It's truly frustrating, especially at lower levels.
Here's an idea.
New spell - Entangling roots.
Magery level: 5
Roots the creature in place for X seconds depending on magery level.
Is this just another paralyze? No.
While paralyze freezes the creature rendering it unable to either attack or move, entangling roots works as a trade off - the creature will realize it's situation and start attacking back again (same effect as when creatures get cornered). You trade of the chasing by taking more damage, risking your safety.
Every other class has some sort of CC preventing creatures from running away, it's only fair the druid has one too. (*edit except for clerics ofcourse.)