Dogs bark and vocalize for many reasons and, while barking can be useful, it can also become excessive. A dog who barks excessively could also be under-occupied and bored. A dog who is distressed by being left alone will also often bark and whine.
In warm weather dogs may be more inclined to bark as windows are open and they are triggered by outdoor sounds, sights and smells.
If a dog is barking at passers-by and other triggers, bring him or her inside. Dogs who are left in yards are exposed to many more triggers for barking than indoor dogs are. Some dogs are more comfortable in one room (especially if being left on their own) than loose in the house so choose a room the dog can be left in and encourage the dog to love this quiet space, by placing things in the area like a comfy dog bed, water, chew sticks or other favourite chewable objects. A radio can help block out the sounds from outside.
If the dog is barking at things he can see from a window, there are inexpensive window privacy treatments owners can install themselves which reduce the amount the dog can see out the window so the dog barks less.
Reward the dog for being quiet. Treat dispensers that pop out a treat after a certain length of silence, so the dog is rewarded for being quiet, are available.
Ensuring the dog gets enough exercise both mentally and physically also reduces their need to bark and provides the stimulation dogs need. Taking up an activity like scent discrimination, agility or one of the many other sports there are for dogs also provide the dog with mental and physical stimulation.
Teaching a dog to bark on cue and then to stop barking on cue helps reduce excessive barking. Dr. Ian Dunbar has a great method for this. Encourage the dog to bark (this can be done by having someone ring the doorbell after you say “speak”). Praise the dog for barking. Once he has learned to bark on cue, teach him the “quiet” cue. Ask him to “speak,” and when he starts barking, say “quiet” and put a treat in front of his nose. He will stop barking to sniff the treat; when he stops barking, give him the treat. Soon he will bark when you cue him with “speak” and will stop barking when you cue him with “quiet”.
Behavior modification is very effective in helping a dog who is anxious about being left alone. A good dog daycare or dog walking service can also be very useful for dogs who bark excessively when left at home.