Right now, the event which define how the cat avoid obstacles should contain how to avoid them I guess, you should have now something like:
Condition_to_avoid | Actions_to_avoid
the idea is simple, we will create a variable, and do this:
Condition_to_avoid | Set Variable to random(100)
If Variable<X | Avoid
Else | Dont_avoid
X is the percentage chance of the cat to avoid the obstacle
If you need more information, or don't understand, don't be affraid to ask.