I think the answers above are pretty much spot on.
What you have is not just a dog management and training issue that must come top priority -- or you will end up with a dead or stolen dog -- but crucially, is also a CHILD and FAMILY management and training issue.
Sometimes dogs aren't a good choice for families at a stage with smaller kids that are allowed to go in and out of front doors and would potentially leave them open... unless (and this isn;t hard to do
)there is a hallway and system of confinement that is observed at all times. But smaller kids, open doors and a dog is a recipe for a dog death or permanent loss -- sadly this is just reality and we have had some tragedies due to exactly this combination on the board in the past that I know you will not want repeated. So solving this must be a real priority as any one of those bolts could end in death -- likely observed by the children who opened the door that time, which would be very traumatic for them.
If you have a bolter then you first have to accept the problem is NOT the dog's behaviour. After all, why wouldn't a lively happy dog view an open door as time to head out and have fun
-- UNLESS you have put in the consistent time and patience to train him otherwise (which would have been easiest as a puppy -- to ask for a sit at the front door, always, and that he is never allowed to go out in front of a person but must wait; and also only proceeds on a release command). Family agreement on how to keep a dog safely inside also needed agreement early on, aspart of a 'family contract' on what we will all do to be responsible for a dog in our home
. The dog has NO idea you want him to stay in if he hasn't had consistent training on this.
It will be considerably harder and more challenging to deal with this now that he has had 18 months of settling into this unwanted pattern and where he knows doors are often simply left open by the kids -- with the obvious message to him, to go out where it is fun, with the kids! But you will have to address this or consider alternatives -- which would be to rehome him so this doesn't end in tragedy, and maybe wait for a dog til kids are older or some system of controlling front door access (eg baby gates) can be installed? But this IS an issue that CAN be successfully managed IF you and your family will put the time and effort into it.
There was a good Victoria Stilwell episode on a famiy that had boxers that would bolt for the front door and jump all over people and bolt outside and this was managed fairly quickly -- thorugh positive, rewards based training. But you will need a good rewards-based trainer in house I think to assess your home layout and also give training advice.
And here you go: Victoria on training dogs not to do this!
http://www.youtube.com/watch?v=ylXQegSagus
As she says -- the need is to train impulse control which isn;t easy and takes time and effort. (btw ignore some of the reader comments after the video -- some total idiots who shouldn;t be allowed to own a dog...
) Has Sparky done one or more general training classes? Do you practice some training/obedience with him every single day? Does he know sit, down and a solid sitstay and downstay? The more a dog has been trained in a fun way, the closer the bond to the owner, the better the natural impulse control, the happier the dog and family, the easier all subsequent training. If he isn;t getting this level of daily practice and hasn;t had a single group rewards-based training class (eg NO 'corrections/leash jerks on collars) then he would greatly benefit and the trainer could help you with this issue. If he has had training then he needs more -- a dog that simply gets put in a downstay won;t be bolting out the door
-- and agin, the trainer could help you with this problem. Look for an APDT or CPDT class/trainer (their websites list trainers locally).
If you have smaller kids I would put child latches on the front door so that they have to get someone older and more cautious/responsible with the dogs to let them out.
But you/they need a routine -- dog kept always in safer parts of the house at ALL times with no access to front door -- but still -- combined with training that every single time he MUST wait before being released to exit (and I'd say only ever *on a lead* and never ever off one). Without knowing your house layout we can;t really give many suggestions but if there's a hallway I'd put a baby gate up. Or put one across the doors that access the hallway.
If this all seems too difficult -- i think there needs to be an all-family talk on 1) that Sparky will need to be rehomed IF everyone doesn't observe the new system and new rules, and everyone agrees to the new system to keep him safe or 2) to say that he will be going to a new home because this is safer for him.
PS and agree with Lani -- 30 minutes walk a day -- probably at a leisurely pace -- is not enough especially for a young dog (that's what I gave my elderly cavalier with heart issues when she was still able to walk and before she passed away...). At last an hour of vigorous walking and mixed with times of active play is needed to tire a dog. And obedience practice -- 20-30 minutes a day, easily split into a couple of short sessions -- will really help tire him out, often far more so than walks!! Of course walks should never be off lead unless safely in a park well away from all cars and traffic. A back garden is nice for a dog but quickly is boring nd never is a replacement for daily interaction with your dog and daily walks -- same smells, same places in a garden. Dogs enjoy a scent-rich world and it works their brains and body to get an active walk where they can explore, smell new things and so on. This is
very important to their quality of life and critical need to be *constantly* socialised with other dogs and people to avoid fear aggression. They need to meet more than the same dog companions. Did you download the free Ian Dunbar book I am sure I mentioned to you early on when you got Sparky? After You Get Your Puppy -- this will still give you loads of great advice and training and game ideas:
www.dogstardaily.com/free-downloads .
** There are some
great books you can get on training tricks and games which dogs love and which tire them out (and crucially again improve the bond with the owner and dog!). Dr Ian Dunbar has a great video you can buy FOR KIDS too, that let them learn how to train their dog themselves -- get your kids involved! There are so many ways to make a dog a more rewarding and active part of the whole family, rather than just a companiion that plays in the garden and gets walked daily.
You can also buy games to train your dog to use -- the Nina Ottosen series is great.
Cavaliers are specifically bred to be fearless and will walk right in front of an oncoming car so cannot stress enough how critical it is to address the bolting and management part of this whole problem though.