Why Do Dogs Bark?

By Dr. Kaitlin Wurtz June 13, 2020

Curious why your dog keeps barking at seemingly nothing? Annoyed that your neighbor’s dog barks all day in their yard? This article addresses this common and completely natural dog behavior and the underlying causes. By understanding the motivation behind a dog’s barking behavior, we can be more effective in altering its occurrence.

Why Do Dogs Bark?

Dogs bark as a form of communication. Barking is an outward expression of a dog’s internal state that other dogs and even humans can understand. Research has shown that people can classify the intent of dog barks based on the sound alone (Pongrácz et al., 2005). More importantly, barking can express both positive and negative emotional states. So dogs may bark when startled, excited, frustrated, fearful, or want to engage in play.

Reasons Why Dogs Bark

Barking is context specific, meaning dogs will alter the frequency, tone, and rhythm of their barks to effectively portray different meanings (Pongrácz et al., 2010). Barking is much more variable in nature compared to other dog vocalizations such as whining, howling, and growling. While scientists think that barking in mammals mostly evolved to notify others of potential danger (Andrew, 1963), dogs have further evolved to use barking in a wide range of contexts (Cohen and Fox, 1976). The main reasons are:

  • Greeting or play

Dogs will use barking to initiate play with another dog or person. They may also perform barking during the play bout. Play barks are typically medium in duration and frequency compared to barks associated with disturbances and isolation (Yin and McCowan, 2004).

  • Threat or defense

Dogs will bark aggressively at a perceived threat in an attempt to scare them away (Vas et al., 2005). Typically, these barks will be low frequency and be long in duration relative to other forms of barking (Yin and McCowan, 2004).

  • Contact seeking/loneliness

Dogs in isolation may bark out of frustration, fear, or as an attempt to seek attention. These barks are typically high frequency and short in duration (Yin and McCowan, 2004).

  • Pain

Some researchers have examined whether the tone of a dog’s bark can be indicative of pain by examining acoustic characteristics of dog’s with spine injuries (Riede et al., 2001), but results remain inconclusive.

Specific Situations When Dogs Bark

Now that you know the main reasons why a dog barks, let’s explore specific situations when dogs bark.

  • Why Do Dogs Bark At Other Dogs?

There could be a number of reasons why your dog is barking at other dogs. Barking can occur when your dog perceives the other dog as a threat. Leashed dogs are more likely to feel intimidated by other dogs due to feeling trapped. They may use their bark as a way to display how large and scary they are in an attempt to get the other dog to leave. Alternatively, dogs may bark to show their excitement from seeing a familiar dog friend and may even use barking in an attempt to initiate play. The sound of the bark, in addition to body language and context, can be used to distinguish between aggressive and play barking.

  • Why Do Dogs Bark At Nothing?

Often times, we think our dogs are barking at nothing. If we don’t know the cause, then we can feel helpless as to how to prevent the barking from happening in the first place. This situation can quickly become a source of frustration for many dog parents. Dogs are able to hear a much wider range of sound frequencies than humans, and they have a much more sensitive sense of smell. While we may not be able to see or hear what our dog is barking at, they may be picking up on something outside of our range of senses. This could include thunder off in the distance, or even the smell of another animal outside. Even during sleep, dogs are actively processing auditory signals and will respond to the sound of alarm-barks from other dogs (Adams and Johnson, 1994). This could be a reason behind your dog randomly barking at night at seemingly nothing.

  • Why Do Dogs Bark At Strangers?

Dogs may bark at strangers as a fear response if they feel intimidated or threatened by them. They may also use barking as a way to alert others of a potential source of danger. People may keep dogs on their property to serve as a sort of security alarm to alert them when visitors arrive.

  • Why Do Dogs Bark At The Door?

If the person at the door is a stranger, dogs will bark for the same reasons mentioned in the above section on “Why Do Dogs Bark At Strangers?” On the other hand, if the dog can see that it is someone they know, then they may bark out of excitement or even impatience if their owner is taking too long to answer the door. If no one is at the door, your dog may be barking to let you know that they want a walk or need to be let out.

  • Why Do Dogs Bark Alone At Home?

When dogs are left home alone, they may feel lonely and anxious. They may bark in an attempt to call their owners back home, or they may bark as an expression of their immense frustration. If you notice your dog barking excessively when left home alone, it may be a sign that your dog is experiencing separation anxiety. In this case, intervention may be necessary to ensure the well-being of your dog and to keep any nearby neighbors amiable.

What Are Reasons For Excessive Barking?

There are 2 main reasons for excessive barking.

  • Individual and Genetic Differences

It’s important to understand that there are huge differences in dogs’ propensities to bark depending on individual and genetic differences. Some breeds such as the Basenji, Chow-chow, and Shar-pei very rarely bark. While breeds like hounds and terriers that have been bred to chase down prey have a much higher propensity to bark. When determining whether your dog’s barking is excessive or not, examine what level of barking is typical for their breed and also consider your dog’s normal barking level. If dogs are barking non-stop at things outside, it could just be that your dog is highly attentive and easily stimulated by outside noises, sights, and smells. This could be due to underlying genetics, or it may be a learned behavior. If they’ve learned that barking at the mailperson to go away actually causes them to leave, then they may be likely to repeat this behavior again in the future. They may also have learned barking from other dogs in the household. All it takes is one dog in the household to start barking and the rest will likely join in. Dogs may also interpret our yelling at them to be quiet as us joining in on the barking with them, further exasperating the problem.

  • Separation Anxiety

Finally, if you notice your dog is barking excessively when left home alone, then this could be due to separation anxiety (Sherman and Mills, 2008). Some dogs may begin to panic when their owners leave them, and barking non-stop may be a way to express their distress. Dogs with separation anxiety may also howl, drool, scratch at doors and windows in an attempt to escape, urinate or defecate in the home, or may be destructive to furniture or other objects in the home.

How To Stop Your Dog From Barking

The most successful way to stop your dog from barking involves reducing or avoiding the stimulus that is causing your dog to bark in the first place. Treating the underlying cause is always going to be more effective than treating the symptoms. Some examples of bark-reducing tools that merely treat the symptom of barking include shock collars that shock your dog’s throat when they bark, citronella collars that spray a small amount of an aversive scent to limit your dogs barking, or even surgical de-barking which physically restructures your dog’s vocal cords to reduce the amount of noise that they can produce when barking. Punishment or physical alterations to reduce barking are not recommended.

Instead, dog parents should work to understand what stimuli their dogs are responding to, and then alter the dog’s environment to reduce exposure to bark-inducing sights, sounds, and smells. Removing a dog’s underlying motivation to bark is the most effective and best long-term solution to excessive barking. If your dog’s stimulus for barking is being left alone, a certified behaviorist or dog trainer with experience with separation anxiety can help guide your pet into feeling comfortable while alone. In addition to training, researchers have shown success with the use of pheromones to reduce stress associated with being left alone (Tod et al., 2005).

Finally, more recent studies are exploring alternatives to bark collars and other forms of punishment. One study implemented the use of an automated feeder that rewards dogs with food when they were quiet for a period of time (Protopopova et al., 2016). These rewarding and calming solutions may have a greater potential for reducing barking than measures that can contribute to increased anxiety, especially when anxiety is likely the root of the problem.


Barking can be a frustrating behavior that our dogs perform, especially when it is excessive. By furthering our understanding of what motivates our dogs to bark, and by shifting our perspective of barking as a means of communication, we can simultaneously improve our dog’s well-being and our quality of life.

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Works Cited

Adams, G. J., & Johnson, K. G. (1994). Behavioural responses to barking and other auditory stimuli during night-time sleeping and waking in the domestic dog (Canis familiaris). Applied Animal Behaviour Science39(2), 151-162.

Andrew, R. J. (1963). The origin and evolution of the calls and facial expressions of the primates. Behaviour, 20(1-2), 1-107.

Cohen, J. A., & Fox, M. W. (1976). Vocalizations in wild canids and possible effects of domestication. Behavioural Processes.

Pongrácz, P., Molnár, C., & Miklósi, Á. (2010). Barking in family dogs: an ethological approach. The Veterinary Journal, 183(2), 141-147.

Pongrácz, P., Molnár, C., Miklósi, A., & Csányi, V. (2005). Human listeners are able to classify dog (Canis familiaris) barks recorded in different situations. Journal of comparative psychology119(2), 136.

Protopopova, A., Kisten, D., & Wynne, C. (2016). Evaluating a humane alternative to the bark collar: Automated differential reinforcement of not barking in a home‐alone setting. Journal of applied behavior analysis49(4), 735-744.

Riede, T., Herzel, H., Hammerschmidt, K., Brunnberg, L., & Tembrock, G. (2001). The harmonic-to-noise ratio applied to dog barks. The Journal of the Acoustical Society of America110(4), 2191-2197.

Sherman, B. L., & Mills, D. S. (2008). Canine anxieties and phobias: an update on separation anxiety and noise aversions. Veterinary Clinics of North America: Small Animal Practice38(5), 1081-1106.

Tod, E., Brander, D., & Waran, N. (2005). Efficacy of dog appeasing pheromone in reducing stress and fear related behaviour in shelter dogs. Applied Animal Behaviour Science93(3-4), 295-308.

Vas, J., Topál, J., Gácsi, M., Miklósi, A., & Csányi, V. (2005). A friend or an enemy? Dogs’ reaction to an unfamiliar person showing behavioural cues of threat and friendliness at different times. Applied Animal Behaviour Science94(1-2), 99-115.

Yin, S., & McCowan, B. (2004). Barking in domestic dogs: context specificity and individual identification. Animal behaviour68(2), 343-355.