Do dogs suffer bereavement like we do?

I have two Cavalier King Charles Spaniels, who are greatly loved and who greatly love, and I feel that I would like to introduce a third member to my 'pack' as they are inseperable, and if the worse happened they would be alone. Do dogs know that a member of their 'pack' either human or canine has died or do they feel deserted and wonder where they have gone? Would a dog have a greater understanding of loss if it came in contact with the deceased, again whether it be human or canine, would it then realise that nature has taken its course, rather than wondering what happened and accept the situation better? I realise a dog can sense illness and never really understood the whole death part. I would be extremely interested to hear your views on this.
Clare Reynolds, by email