Barking dogs can be an annoyance to pet owners and neighbors, but there's usually something behind the bark that can be addressed and resolved. If your dog is barking suddenly for no apparent reason, and is difficult to calm, consult your vet for a full checkup to ensure there are no underlying health issues.
Train your dog to follow basic obedience commands or hire a trainer to do it for you. Dogs who understand your expectations and know how to follow simple commands are more likely to respond to instruction. Train against unwanted barking by ignoring the behavior when it occurs or giving your dog a "timeout" away from you. Reward your pup when he behaves, especially when he's in an environment where he'd usually bark, like when a doorbell rings. Practice saying the word, "quiet" when your dog barks and reward him when he stops.
Play With Him
Dogs who are well-exercised and played with are less likely to bark endlessly, especially due to boredom, loneliness or separation anxiety. Walk your dog, play with him and give him physical love and attention throughout the day. If your pup is home alone for long stretches of time, consider hiring a dog walker or neighbor to check on him and interact with him during the day. This is especially important if your dog is outside during the day, and his barking is noticed by and complained about by neighbors.
Keep Him Busy
Give your dog something to do besides bark. Interactive toys that require movement to release kibble can hold his attention, as can the companionship of other household pets. Dogs can relieve stress, anxiety and boredom through chewing, so provide him with different chew toys to occupy his time. Don't reward a barking dog with a toy or treat to quiet him -- that only reinforces the unwanted behavior.
Remove Barking Stimuli
Removing your dog from situations where he barks, or limiting access to things he barks at can help curb noisy behavior. For example, if your dog barks at birds outside a window, use weighted shades, blinds or curtains to limit his view. If he barks at dogs in his vicinity, employ the help of neighbors to introduce the animals and get them accustomed to each other to limit unwanted barking. If you continue to have problems quieting a barking dog, consult a canine behavioral specialist for advice.
Accept Some Barking
It's natural for dogs to bark as a way of greeting people and other animals, as a way to express fear and to protect their territory. Don't expect to stop your dog's natural barking inclinations -- teach him when it's inappropriate to bark and to follow your commands. Never physically punish or yell at your dog when he barks -- it won't stop the problem and can build fear and mistrust.