Where do you live and where are you planning to live abroard. There are very strict entry requirements for travelling with animals and very few airlines, if any, will allow a large dog in the cabin.
You really need to get the dog assessed by a professional before you make any decisions. A five year old dog will be difficult to retrain and will need many hours of tour attention daily. I have fostered and rehomed over 70 dogs and have dealt with many problem ones. They are a full time 24/7 hard work. Please think carefully