Dogs bark for a reason. As a relative of the wolf who lives in packs, barking serves as a language. And you are a member of his pack, perhaps the only other member. His barking is aimed at you. So what's he saying? This may seem a complex task but it quite often simply imnvolves going through a checklist of what could be happening. So before behavioral issues are looked at go through this checklist to see if there are external issues affecting your dog and creating the barking.

Health

Ensure your dog is physically OK and in no pain or discomfort.

Visit the vet at least once a year.

Keep your pet clean and groomed.

Check for injuries, dental issues, ear problems and pad problems.

Make sure the collar fits well...if it rubs it could be causing pain.

Keep a watchful eye on his hearing and vision.

Make sure he is up to date on shots: heartworm prevention, fleas, ticks, mites,

Clip his claws to prevent tearing and possible infection.

Keep up with how a dog's needs change as they age (e.g. the type and quantity of food will change)

Dogs can develop allergies. Get to a vet if you think this has happened.

Surroundings

Is he outdoors? Pack animals want contact and don't like being left alone outside. Bring him in or get a companion dog. Often just seeing you is enough so give him line of sight if possible e.g. opening the curtains. Dogs often feel more secure when they can go into a structure like a dog house.

Is he free to roam or is he tied up - which could frustrate him? If his tether is too short he could be anxious.

Can the dog lie down, sit and stand with no problem? If you'd be uncomfortable so will he.

Inside give him his own spot to rest in e.g. a bed, a chair or a crate. This becomes his space.

Climate

Is it uncomfortable temp wise? Dogs with fur need a cool area and short-haired may need supplemental warmth...heaters or blankets. If it's hot, sunny or wet does he have a covered place to lie down? Take the dog inside or ensure access to shelter with a dog-house. Dog's pads can get burned by walking on hot pavement. Try it barefoot yourself. Grass is much better.

Food

Is he hungry or thirsty? I'd get testy if I were either...so does your dog. Provide fresh water and food twice a day.