Behavioral problems often cause an owner to feel they must give up their pet. Problems can range from submissive urination to dangerous aggression, from destructiveness to disobedience, from too active and playful to ignoring you completely. Identifying exactly what is the cause of the problem is sometimes half the battle. For instance, destructiveness is usually caused by boredom.
Getting your pet neutered will affect all behaviors stemming from the sex drive, almost always for the better. This includes some dominance aggression and inappropriate marking (lifting his leg). If the pet is older and the behaviors have become habitual, the effect of neutering might not be as strong. It will also take longer for the effects to be seen in an older pet, sometimes many weeks. But, unless your pet is a choice breeding specimen, please get your dog neutered. It will prolong his life too.
One of the first things you must do is to have your pet checked out by your vet. Be frank with your vet about the behavior problems, they can stem from pain, a breed tendency, or even hormone levels that are off. Give your pet the benefit of the doubt that the problem can stem from a physical cause, for instance many a urinary infection has caused housebreaking problems, especially if the animal was housebroken before. In the meantime, do work on trying to correct the problem behaviorally, let them know what is and is not acceptable behavior.
If your pet is aggressive, and has bitten or you think he/she might bite, please see a trainer or behaviorist. A behaviorist is one who specializes in training beyond basic manners. Again, be very frank with this person. Many, many, most, ALMOST all dogs can be helped with proper training. The hardest part is actually training the humans.
Some aggressive animals cannot be saved, and it is often better to euthanize these animals than to pass along the problem and danger to someone else. Please work up the courage to take him to your vet for this, so he/she can go out with someone he/she loves, instead of a cold shelter, with a rescue worker who's heart has to break many times a day over these animals.
If medical problems have been ruled out and you are struggling with a pet with behavioral issues, we can recommend the following trainers in this area:
An Educated Dog Jennifer Aho "Creating the relationship you want with your dog"
Absolute K9 Solutions (Lunenburg, MA) http://www.dogtrainerma.com
Gemini (Littleton, MA): http://www.geminidogs.com/
All Dogs Gym (Manchester, NH): http://www.alldogsgym.com/
Granite State Dog Training (Amherst, NH): http://www.gsdtc.com/
Riverside K9(Nashua, NH): http://www.riversidek9.com/
The Curious Canine (Fitchburg, MA): http://www.curiouscanine.com/ locations.html