We have just taken on a male 3.5 year old  welsh springer spaniel yesterday from  someone who didnt have time for him. We also have a 4 year old ridgeback who has know this dog since they were puppys and get on excellent. He has really bad seperation anxiety as he has always been able to go where he wants in the house and to be very clingy to his old owner.
We dont let our dog upstairs and is left some of the day and is fine.

We have got our ridgeback really well trained and laid back. but just need to know what to do to stop him howling as soon as he is left. We are doing the same with the new dog as we did with our ridgeback and sure he will come around.

Should we just let him howl alnight or stay down stairs with him and work on him during the day. Im worried because our ridgeback is really timid and i think  all the noise will stress him.

People have recommanded an anti bark collar but think we dont need this?

Any ideas will be really helpful.

Is the training different as he is older and had the problem for a while. we have read the causes of this problem and he has had all these.

Do you know if he did this at night with his last owners? only asking because they may of re-enforced this behaviour by going to him when he was noisy. Or did he sleep with them so is used to company at night maybe.if this is the case he will take time to settle into your routine but with your dog for company he should get used to where he sleeps.
i wouldn't go to him a night as i've always ignored barking or crying at night with my dogs when they were pups and settled after a couple of nights, if you go to him he will learn that there is no reward for the noise and should stop but with older dogs this can take longer to have affect.
As long as you know he doesn't need the toilet and has water and toys etc i would say leave him, i'm sure your dog will be fine. if your dog shows signs of distress thats different but my dogs sleep through just about anything.
During the day i would practise going out for a minute at a time then longer making sure you don't speak or give eye contact before or after you return. if you do this  over a few days but keep going out for a little longer then he will stop stressing as he will learn that your coming back. treat him like you would a puppy that your teaching to be left. also leave him plenty of things to chew and play with.
if your going out it is always a good idea to give him a good walk first so that he's tired and  this really helps keep the stress levels down.
because you already have a dog he will soon pick up your dogs good habbits and he's always got company so should learn to settle as soon as he's more used to your routine.
Training classes are always a good idea as you will bond with your new dog better and teach him what you want from him. don't always spend time with both dogs, try and take them out on their own for some walks so the both get your quality time.
i'm sure everything will settle down very soon but don't expect too much from him to soon as this is so new to him.            

If you've only taken him on in the past couple of days the poor lad is bound to be badly unsettled and 'homesick'. An anti-bark collar would be disastrous - punishment for fear and unhappiness won't make him happy and confident; quite the opposite, it'll only make matters far worse.

Basically you're dealing with two distinct but related problems: a new rescue dog (with all the baggage that can entail) and separation anxiety. Settling in a new rescue dog without any obvious problems can take weeks or months; when there's an existing problem as well then you really need to seek professional help from a reputable behaviourist. Your best bet is to to ask your vet to refer you - don't just pick someone from the Yellow Pages.

I agree with Jeangenie, he needs time to settle into a new routine and you just need to be patient.  Continue with the routine you have with your dog and within a few weeks he should be settling into it.  However, if he does have other problems then a behaviourist might be what you need to help him settle. 

Well done for taking this boy in and be patient it will pay off,  hopefully the two dogs will become best friends as my two have :)