Chasing Golf Carts

Question
I have two labrador retrievers, 8 and 9 years old.  They get 4 or 5 long walks daily.  The golf cart is the primary mode of transportation in our neighborhood; on a typical walk they will encounter at least 15 carts.  Suddenly, about a month ago, having never done it before, the dogs started attacking and chasing golf carts that drive by.  I cannot hold back 200 lbs. of Labs.  It is selective, some carts are ignored and some are attacked with wild lunging and barking.  Shock collar has not been the answer.  One of the dogs wants to chase so badly that he will chase in spite of the shock.  Pinch collars get no respect either.  

Now, it has escalated to chasing up and down the porch when a cart goes by. The newest behavior includes leaping toward the doors and windows when the dogs are in the house and a cart goes by.  They have actually broken some household items.  What is going on? What is the answer?   They were previously sweet, docile pets.

Answer
Hi Crystal,

It's hard to say what it could be. It could be a lot of things: trauma that they view as cart related, one dog feeding off the other, correction actually increasing the reaction time (my guess), noise sensitivity as they age....

You may want to muffle the sound with dog muffs www.safesounds.com  and walking them separately with treats rewarding at a non reactive distance and eventually recombining them on walks with something non aversive like a sensation harness www.softouchconcepts.com.