Few questions that might help others in answering your ?.How old is Dougal & how long have you had him.
How was Dougal at your Previous address.
Sorry if this is a long post but just to let you know i symphize with you.
I aint an expert and sure you will get lot's of advice from others more trained to answer your question.
I would definitely get a long line( we use a lunge rein for horses) and go back to basics heel work & recall. Even playtime needs to be a training session, we make Jack wait before fetching a retrieve and i usually throw a retrieve in one direction walk in another and call Jack to me before sending him for retrieve.
Reading Jacks story below it doesn't sound great , but believe me everyone has noticed a great difference & we can now walk past ducks without him going to drag us in.
We got Jack in Dec 07 at 14 months old. The 1st time we let him off he ploughed into a thicket of brambles, without any care of injury to himself & it took us ages to get him out.
We went back to basics with Jack and had him on a long line. Thought we had cracked it, then 2 months ago he proved us wrong by picking up a scent & following it across the local bypass fri tea

rush hour, had a guardian angel & made without injury, although my state of mind wasn't without injury.
Back to basic & long line.
In all other ways Jack is so good, teaching him new things is easy but undoing the bad habits he's picked up is hard eg stop whistle & recall went out the window again last week when he chased a cat.
Now i've got people asking why he's back on long line as he's so good and he only chased a cat

. Yes but he'd not got a care where we where
I think people think we want him to be like Harvey our working dog, but we just want him to be SAFE. Our terrier chases squirrels but only for a short distance and not out of sight.
We have been following Mollys story and decided if we ain't got there after a while we will look to a trainer for help:( As like you we don,t want a dog thats a danger to himself).
Best of Luck at least you sympthize with your wife, I was asked why i wasn't watching him the 1st time, guess who got asked the same thing last week when hubby had him out