Some vocal breeds like Beagles, Chihuahuas and Terriers were bred to bark frequently
Breed Tendency
Dogs developed to guard like Shepherds and Dobermans bark readily at perceived threats.
Alarm Dog Origins
Dogs allowed to bark readily without training are prone to barking habits.
Lack of Training
Barking defends territory. Territorial breeds and insecure dogs bark more.
Territorialness
Nervous dogs use barking to keep perceived threats away. Confident dogs bark less.
Fear
Dogs learn barking garners owner attention, prompting more bark demands.
Demanding Attention
Dogs with separation anxiety may bark, howl and whine when alone.
Separation Anxiety